Merge branch 'master' into abi-offset-fixed-arrays

23 files changed, 1086 insertions, 958 deletions

diff --git a/accounts/abi/abi.go b/accounts/abi/abi.go
index 2a06d474b..205dc300b 100644
--- a/accounts/abi/abi.go
+++ b/accounts/abi/abi.go
@@ -20,10 +20,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"reflect"
-	"strings"
-
-	"github.com/ethereum/go-ethereum/common"
 )
 
 // The ABI holds information about a contract's context and available
@@ -76,106 +72,27 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
 	return append(method.Id(), arguments...), nil
 }
 
-// these variable are used to determine certain types during type assertion for
-// assignment.
-var (
-	r_interSlice = reflect.TypeOf([]interface{}{})
-	r_hash       = reflect.TypeOf(common.Hash{})
-	r_bytes      = reflect.TypeOf([]byte{})
-	r_byte       = reflect.TypeOf(byte(0))
-)
-
 // Unpack output in v according to the abi specification
-func (abi ABI) Unpack(v interface{}, name string, output []byte) error {
-	var method = abi.Methods[name]
-
-	if len(output) == 0 {
-		return fmt.Errorf("abi: unmarshalling empty output")
-	}
-
-	// make sure the passed value is a pointer
-	valueOf := reflect.ValueOf(v)
-	if reflect.Ptr != valueOf.Kind() {
-		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+func (abi ABI) Unpack(v interface{}, name string, output []byte) (err error) {
+	if err = bytesAreProper(output); err != nil {
+		return err
 	}
-
-	var (
-		value = valueOf.Elem()
-		typ   = value.Type()
-	)
-
-	if len(method.Outputs) > 1 {
-		switch value.Kind() {
-		// struct will match named return values to the struct's field
-		// names
-		case reflect.Struct:
-			for i := 0; i < len(method.Outputs); i++ {
-				marshalledValue, err := toGoType(i, method.Outputs[i], output)
-				if err != nil {
-					return err
-				}
-				reflectValue := reflect.ValueOf(marshalledValue)
-
-				for j := 0; j < typ.NumField(); j++ {
-					field := typ.Field(j)
-					// TODO read tags: `abi:"fieldName"`
-					if field.Name == strings.ToUpper(method.Outputs[i].Name[:1])+method.Outputs[i].Name[1:] {
-						if err := set(value.Field(j), reflectValue, method.Outputs[i]); err != nil {
-							return err
-						}
-					}
-				}
-			}
-		case reflect.Slice:
-			if !value.Type().AssignableTo(r_interSlice) {
-				return fmt.Errorf("abi: cannot marshal tuple in to slice %T (only []interface{} is supported)", v)
-			}
-
-			// if the slice already contains values, set those instead of the interface slice itself.
-			if value.Len() > 0 {
-				if len(method.Outputs) > value.Len() {
-					return fmt.Errorf("abi: cannot marshal in to slices of unequal size (require: %v, got: %v)", len(method.Outputs), value.Len())
-				}
-
-				for i := 0; i < len(method.Outputs); i++ {
-					marshalledValue, err := toGoType(i, method.Outputs[i], output)
-					if err != nil {
-						return err
-					}
-					reflectValue := reflect.ValueOf(marshalledValue)
-					if err := set(value.Index(i).Elem(), reflectValue, method.Outputs[i]); err != nil {
-						return err
-					}
-				}
-				return nil
-			}
-
-			// create a new slice and start appending the unmarshalled
-			// values to the new interface slice.
-			z := reflect.MakeSlice(typ, 0, len(method.Outputs))
-			for i := 0; i < len(method.Outputs); i++ {
-				marshalledValue, err := toGoType(i, method.Outputs[i], output)
-				if err != nil {
-					return err
-				}
-				z = reflect.Append(z, reflect.ValueOf(marshalledValue))
-			}
-			value.Set(z)
-		default:
-			return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
-		}
-
+	// since there can't be naming collisions with contracts and events,
+	// we need to decide whether we're calling a method or an event
+	var unpack unpacker
+	if method, ok := abi.Methods[name]; ok {
+		unpack = method
+	} else if event, ok := abi.Events[name]; ok {
+		unpack = event
 	} else {
-		marshalledValue, err := toGoType(0, method.Outputs[0], output)
-		if err != nil {
-			return err
-		}
-		if err := set(value, reflect.ValueOf(marshalledValue), method.Outputs[0]); err != nil {
-			return err
-		}
+		return fmt.Errorf("abi: could not locate named method or event.")
 	}
 
-	return nil
+	// requires a struct to unpack into for a tuple return...
+	if unpack.isTupleReturn() {
+		return unpack.tupleUnpack(v, output)
+	}
+	return unpack.singleUnpack(v, output)
 }
 
 func (abi *ABI) UnmarshalJSON(data []byte) error {
diff --git a/accounts/abi/abi_test.go b/accounts/abi/abi_test.go
index 5420eb19a..2ae7488a4 100644
--- a/accounts/abi/abi_test.go
+++ b/accounts/abi/abi_test.go
@@ -29,25 +29,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
-// formatSilceOutput add padding to the value and adds a size
-func formatSliceOutput(v ...[]byte) []byte {
-	off := common.LeftPadBytes(big.NewInt(int64(len(v))).Bytes(), 32)
-	output := append(off, make([]byte, 0, len(v)*32)...)
-
-	for _, value := range v {
-		output = append(output, common.LeftPadBytes(value, 32)...)
-	}
-	return output
-}
-
-// quick helper padding
-func pad(input []byte, size int, left bool) []byte {
-	if left {
-		return common.LeftPadBytes(input, size)
-	}
-	return common.RightPadBytes(input, size)
-}
-
 const jsondata = `
 [
 	{ "type" : "function", "name" : "balance", "constant" : true },
@@ -191,7 +172,7 @@ func TestMethodSignature(t *testing.T) {
 		t.Errorf("expected ids to match %x != %x", m.Id(), idexp)
 	}
 
-	uintt, _ := NewType("uint")
+	uintt, _ := NewType("uint256")
 	m = Method{"foo", false, []Argument{{"bar", uintt, false}}, nil}
 	exp = "foo(uint256)"
 	if m.Sig() != exp {
diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index 0621e81c2..09288d401 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -41,6 +41,7 @@ import (
 var _ bind.ContractBackend = (*SimulatedBackend)(nil)
 
 var errBlockNumberUnsupported = errors.New("SimulatedBackend cannot access blocks other than the latest block")
+var errGasEstimationFailed = errors.New("gas required exceeds allowance or always failing transaction")
 
 // SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
 // the background. Its main purpose is to allow easily testing contract bindings.
@@ -59,7 +60,7 @@ type SimulatedBackend struct {
 // for testing purposes.
 func NewSimulatedBackend(alloc core.GenesisAlloc) *SimulatedBackend {
 	database, _ := ethdb.NewMemDatabase()
-	genesis := core.Genesis{Config: params.AllProtocolChanges, Alloc: alloc}
+	genesis := core.Genesis{Config: params.AllEthashProtocolChanges, Alloc: alloc}
 	genesis.MustCommit(database)
 	blockchain, _ := core.NewBlockChain(database, genesis.Config, ethash.NewFaker(), vm.Config{})
 	backend := &SimulatedBackend{database: database, blockchain: blockchain, config: genesis.Config}
@@ -203,32 +204,46 @@ func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMs
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
-	// Binary search the gas requirement, as it may be higher than the amount used
+	// Determine the lowest and highest possible gas limits to binary search in between
 	var (
-		lo uint64 = params.TxGas - 1
-		hi uint64
+		lo  uint64 = params.TxGas - 1
+		hi  uint64
+		cap uint64
 	)
 	if call.Gas != nil && call.Gas.Uint64() >= params.TxGas {
 		hi = call.Gas.Uint64()
 	} else {
 		hi = b.pendingBlock.GasLimit().Uint64()
 	}
-	for lo+1 < hi {
-		// Take a guess at the gas, and check transaction validity
-		mid := (hi + lo) / 2
-		call.Gas = new(big.Int).SetUint64(mid)
+	cap = hi
+
+	// Create a helper to check if a gas allowance results in an executable transaction
+	executable := func(gas uint64) bool {
+		call.Gas = new(big.Int).SetUint64(gas)
 
 		snapshot := b.pendingState.Snapshot()
 		_, _, failed, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
 		b.pendingState.RevertToSnapshot(snapshot)
 
-		// If the transaction became invalid or execution failed, raise the gas limit
 		if err != nil || failed {
+			return false
+		}
+		return true
+	}
+	// Execute the binary search and hone in on an executable gas limit
+	for lo+1 < hi {
+		mid := (hi + lo) / 2
+		if !executable(mid) {
 			lo = mid
-			continue
+		} else {
+			hi = mid
+		}
+	}
+	// Reject the transaction as invalid if it still fails at the highest allowance
+	if hi == cap {
+		if !executable(hi) {
+			return nil, errGasEstimationFailed
 		}
-		// Otherwise assume the transaction succeeded, lower the gas limit
-		hi = mid
 	}
 	return new(big.Int).SetUint64(hi), nil
 }
diff --git a/accounts/abi/bind/bind.go b/accounts/abi/bind/bind.go
index f58758088..4dce79b77 100644
--- a/accounts/abi/bind/bind.go
+++ b/accounts/abi/bind/bind.go
@@ -129,7 +129,7 @@ func Bind(types []string, abis []string, bytecodes []string, pkg string, lang La
 		return string(code), nil
 	}
 	// For all others just return as is for now
-	return string(buffer.Bytes()), nil
+	return buffer.String(), nil
 }
 
 // bindType is a set of type binders that convert Solidity types to some supported
diff --git a/accounts/abi/error.go b/accounts/abi/error.go
index 420acf418..9d8674ad0 100644
--- a/accounts/abi/error.go
+++ b/accounts/abi/error.go
@@ -39,22 +39,23 @@ func formatSliceString(kind reflect.Kind, sliceSize int) string {
 // type in t.
 func sliceTypeCheck(t Type, val reflect.Value) error {
 	if val.Kind() != reflect.Slice && val.Kind() != reflect.Array {
-		return typeErr(formatSliceString(t.Kind, t.SliceSize), val.Type())
+		return typeErr(formatSliceString(t.Kind, t.Size), val.Type())
 	}
-	if t.IsArray && val.Len() != t.SliceSize {
-		return typeErr(formatSliceString(t.Elem.Kind, t.SliceSize), formatSliceString(val.Type().Elem().Kind(), val.Len()))
+
+	if t.T == ArrayTy && val.Len() != t.Size {
+		return typeErr(formatSliceString(t.Elem.Kind, t.Size), formatSliceString(val.Type().Elem().Kind(), val.Len()))
 	}
 
-	if t.Elem.IsSlice {
+	if t.Elem.T == SliceTy {
 		if val.Len() > 0 {
 			return sliceTypeCheck(*t.Elem, val.Index(0))
 		}
-	} else if t.Elem.IsArray {
+	} else if t.Elem.T == ArrayTy {
 		return sliceTypeCheck(*t.Elem, val.Index(0))
 	}
 
 	if elemKind := val.Type().Elem().Kind(); elemKind != t.Elem.Kind {
-		return typeErr(formatSliceString(t.Elem.Kind, t.SliceSize), val.Type())
+		return typeErr(formatSliceString(t.Elem.Kind, t.Size), val.Type())
 	}
 	return nil
 }
@@ -62,20 +63,19 @@ func sliceTypeCheck(t Type, val reflect.Value) error {
 // typeCheck checks that the given reflection value can be assigned to the reflection
 // type in t.
 func typeCheck(t Type, value reflect.Value) error {
-	if t.IsSlice || t.IsArray {
+	if t.T == SliceTy || t.T == ArrayTy {
 		return sliceTypeCheck(t, value)
 	}
 
 	// Check base type validity. Element types will be checked later on.
 	if t.Kind != value.Kind() {
 		return typeErr(t.Kind, value.Kind())
+	} else if t.T == FixedBytesTy && t.Size != value.Len() {
+		return typeErr(t.Type, value.Type())
+	} else {
+		return nil
 	}
-	return nil
-}
 
-// varErr returns a formatted error.
-func varErr(expected, got reflect.Kind) error {
-	return typeErr(expected, got)
 }
 
 // typeErr returns a formatted type casting error.
diff --git a/accounts/abi/event.go b/accounts/abi/event.go
index 51ab84241..44ed7b8df 100644
--- a/accounts/abi/event.go
+++ b/accounts/abi/event.go
@@ -18,6 +18,7 @@ package abi
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -44,3 +45,93 @@ func (e Event) Id() common.Hash {
 	}
 	return common.BytesToHash(crypto.Keccak256([]byte(fmt.Sprintf("%v(%v)", e.Name, strings.Join(types, ",")))))
 }
+
+// unpacks an event return tuple into a struct of corresponding go types
+//
+// Unpacking can be done into a struct or a slice/array.
+func (e Event) tupleUnpack(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	var (
+		value = valueOf.Elem()
+		typ   = value.Type()
+	)
+
+	if value.Kind() != reflect.Struct {
+		return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
+	}
+
+	j := 0
+	for i := 0; i < len(e.Inputs); i++ {
+		input := e.Inputs[i]
+		if input.Indexed {
+			// can't read, continue
+			continue
+		} else if input.Type.T == ArrayTy {
+			// need to move this up because they read sequentially
+			j += input.Type.Size
+		}
+		marshalledValue, err := toGoType((i+j)*32, input.Type, output)
+		if err != nil {
+			return err
+		}
+		reflectValue := reflect.ValueOf(marshalledValue)
+
+		switch value.Kind() {
+		case reflect.Struct:
+			for j := 0; j < typ.NumField(); j++ {
+				field := typ.Field(j)
+				// TODO read tags: `abi:"fieldName"`
+				if field.Name == strings.ToUpper(e.Inputs[i].Name[:1])+e.Inputs[i].Name[1:] {
+					if err := set(value.Field(j), reflectValue, e.Inputs[i]); err != nil {
+						return err
+					}
+				}
+			}
+		case reflect.Slice, reflect.Array:
+			if value.Len() < i {
+				return fmt.Errorf("abi: insufficient number of arguments for unpack, want %d, got %d", len(e.Inputs), value.Len())
+			}
+			v := value.Index(i)
+			if v.Kind() != reflect.Ptr && v.Kind() != reflect.Interface {
+				return fmt.Errorf("abi: cannot unmarshal %v in to %v", v.Type(), reflectValue.Type())
+			}
+			reflectValue := reflect.ValueOf(marshalledValue)
+			if err := set(v.Elem(), reflectValue, e.Inputs[i]); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
+		}
+	}
+	return nil
+}
+
+func (e Event) isTupleReturn() bool { return len(e.Inputs) > 1 }
+
+func (e Event) singleUnpack(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	if e.Inputs[0].Indexed {
+		return fmt.Errorf("abi: attempting to unpack indexed variable into element.")
+	}
+
+	value := valueOf.Elem()
+
+	marshalledValue, err := toGoType(0, e.Inputs[0].Type, output)
+	if err != nil {
+		return err
+	}
+	if err := set(value, reflect.ValueOf(marshalledValue), e.Inputs[0]); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/accounts/abi/event_test.go b/accounts/abi/event_test.go
index b5054a032..7e2f13f76 100644
--- a/accounts/abi/event_test.go
+++ b/accounts/abi/event_test.go
@@ -31,7 +31,7 @@ func TestEventId(t *testing.T) {
 	}{
 		{
 			definition: `[
-			{ "type" : "event", "name" : "balance", "inputs": [{ "name" : "in", "type": "uint" }] },
+			{ "type" : "event", "name" : "balance", "inputs": [{ "name" : "in", "type": "uint256" }] },
 			{ "type" : "event", "name" : "check", "inputs": [{ "name" : "t", "type": "address" }, { "name": "b", "type": "uint256" }] }
 			]`,
 			expectations: map[string]common.Hash{
diff --git a/accounts/abi/method.go b/accounts/abi/method.go
index 32077e8a6..609a71f07 100644
--- a/accounts/abi/method.go
+++ b/accounts/abi/method.go
@@ -88,6 +88,85 @@ func (method Method) pack(args ...interface{}) ([]byte, error) {
 	return ret, nil
 }
 
+// unpacks a method return tuple into a struct of corresponding go types
+//
+// Unpacking can be done into a struct or a slice/array.
+func (method Method) tupleUnpack(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	var (
+		value = valueOf.Elem()
+		typ   = value.Type()
+	)
+
+	j := 0
+	for i := 0; i < len(method.Outputs); i++ {
+		toUnpack := method.Outputs[i]
+		if toUnpack.Type.T == ArrayTy {
+			// need to move this up because they read sequentially
+			j += toUnpack.Type.Size
+		}
+		marshalledValue, err := toGoType((i+j)*32, toUnpack.Type, output)
+		if err != nil {
+			return err
+		}
+		reflectValue := reflect.ValueOf(marshalledValue)
+
+		switch value.Kind() {
+		case reflect.Struct:
+			for j := 0; j < typ.NumField(); j++ {
+				field := typ.Field(j)
+				// TODO read tags: `abi:"fieldName"`
+				if field.Name == strings.ToUpper(method.Outputs[i].Name[:1])+method.Outputs[i].Name[1:] {
+					if err := set(value.Field(j), reflectValue, method.Outputs[i]); err != nil {
+						return err
+					}
+				}
+			}
+		case reflect.Slice, reflect.Array:
+			if value.Len() < i {
+				return fmt.Errorf("abi: insufficient number of arguments for unpack, want %d, got %d", len(method.Outputs), value.Len())
+			}
+			v := value.Index(i)
+			if v.Kind() != reflect.Ptr && v.Kind() != reflect.Interface {
+				return fmt.Errorf("abi: cannot unmarshal %v in to %v", v.Type(), reflectValue.Type())
+			}
+			reflectValue := reflect.ValueOf(marshalledValue)
+			if err := set(v.Elem(), reflectValue, method.Outputs[i]); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
+		}
+	}
+	return nil
+}
+
+func (method Method) isTupleReturn() bool { return len(method.Outputs) > 1 }
+
+func (method Method) singleUnpack(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	value := valueOf.Elem()
+
+	marshalledValue, err := toGoType(0, method.Outputs[0].Type, output)
+	if err != nil {
+		return err
+	}
+	if err := set(value, reflect.ValueOf(marshalledValue), method.Outputs[0]); err != nil {
+		return err
+	}
+	return nil
+}
+
 // Sig returns the methods string signature according to the ABI spec.
 //
 // Example
diff --git a/accounts/abi/numbers.go b/accounts/abi/numbers.go
index 5d3efff52..9ad99f90d 100644
--- a/accounts/abi/numbers.go
+++ b/accounts/abi/numbers.go
@@ -25,36 +25,23 @@ import (
 )
 
 var (
-	big_t     = reflect.TypeOf(big.Int{})
-	ubig_t    = reflect.TypeOf(big.Int{})
-	byte_t    = reflect.TypeOf(byte(0))
-	byte_ts   = reflect.TypeOf([]byte(nil))
-	uint_t    = reflect.TypeOf(uint(0))
-	uint8_t   = reflect.TypeOf(uint8(0))
-	uint16_t  = reflect.TypeOf(uint16(0))
-	uint32_t  = reflect.TypeOf(uint32(0))
-	uint64_t  = reflect.TypeOf(uint64(0))
-	int_t     = reflect.TypeOf(int(0))
-	int8_t    = reflect.TypeOf(int8(0))
-	int16_t   = reflect.TypeOf(int16(0))
-	int32_t   = reflect.TypeOf(int32(0))
-	int64_t   = reflect.TypeOf(int64(0))
-	hash_t    = reflect.TypeOf(common.Hash{})
-	address_t = reflect.TypeOf(common.Address{})
-
-	uint_ts   = reflect.TypeOf([]uint(nil))
-	uint8_ts  = reflect.TypeOf([]uint8(nil))
-	uint16_ts = reflect.TypeOf([]uint16(nil))
-	uint32_ts = reflect.TypeOf([]uint32(nil))
-	uint64_ts = reflect.TypeOf([]uint64(nil))
-	ubig_ts   = reflect.TypeOf([]*big.Int(nil))
-
-	int_ts   = reflect.TypeOf([]int(nil))
-	int8_ts  = reflect.TypeOf([]int8(nil))
-	int16_ts = reflect.TypeOf([]int16(nil))
-	int32_ts = reflect.TypeOf([]int32(nil))
-	int64_ts = reflect.TypeOf([]int64(nil))
-	big_ts   = reflect.TypeOf([]*big.Int(nil))
+	big_t      = reflect.TypeOf(&big.Int{})
+	derefbig_t = reflect.TypeOf(big.Int{})
+	uint8_t    = reflect.TypeOf(uint8(0))
+	uint16_t   = reflect.TypeOf(uint16(0))
+	uint32_t   = reflect.TypeOf(uint32(0))
+	uint64_t   = reflect.TypeOf(uint64(0))
+	int_t      = reflect.TypeOf(int(0))
+	int8_t     = reflect.TypeOf(int8(0))
+	int16_t    = reflect.TypeOf(int16(0))
+	int32_t    = reflect.TypeOf(int32(0))
+	int64_t    = reflect.TypeOf(int64(0))
+	address_t  = reflect.TypeOf(common.Address{})
+	int_ts     = reflect.TypeOf([]int(nil))
+	int8_ts    = reflect.TypeOf([]int8(nil))
+	int16_ts   = reflect.TypeOf([]int16(nil))
+	int32_ts   = reflect.TypeOf([]int32(nil))
+	int64_ts   = reflect.TypeOf([]int64(nil))
 )
 
 // U256 converts a big Int into a 256bit EVM number.
diff --git a/accounts/abi/pack.go b/accounts/abi/pack.go
index 4d8a3f031..072e80536 100644
--- a/accounts/abi/pack.go
+++ b/accounts/abi/pack.go
@@ -61,8 +61,9 @@ func packElement(t Type, reflectValue reflect.Value) []byte {
 			reflectValue = mustArrayToByteSlice(reflectValue)
 		}
 		return common.RightPadBytes(reflectValue.Bytes(), 32)
+	default:
+		panic("abi: fatal error")
 	}
-	panic("abi: fatal error")
 }
 
 // packNum packs the given number (using the reflect value) and will cast it to appropriate number representation
@@ -74,6 +75,8 @@ func packNum(value reflect.Value) []byte {
 		return U256(big.NewInt(value.Int()))
 	case reflect.Ptr:
 		return U256(value.Interface().(*big.Int))
+	default:
+		panic("abi: fatal error")
 	}
-	return nil
+
 }
diff --git a/accounts/abi/pack_test.go b/accounts/abi/pack_test.go
index c6cfb56ea..36401ee67 100644
--- a/accounts/abi/pack_test.go
+++ b/accounts/abi/pack_test.go
@@ -322,12 +322,12 @@ func TestPack(t *testing.T) {
 	} {
 		typ, err := NewType(test.typ)
 		if err != nil {
-			t.Fatal("unexpected parse error:", err)
+			t.Fatalf("%v failed. Unexpected parse error: %v", i, err)
 		}
 
 		output, err := typ.pack(reflect.ValueOf(test.input))
 		if err != nil {
-			t.Fatal("unexpected pack error:", err)
+			t.Fatalf("%v failed. Unexpected pack error: %v", i, err)
 		}
 
 		if !bytes.Equal(output, test.output) {
@@ -435,7 +435,4 @@ func TestPackNumber(t *testing.T) {
 			t.Errorf("test %d: pack mismatch: have %x, want %x", i, packed, tt.packed)
 		}
 	}
-	if packed := packNum(reflect.ValueOf("string")); packed != nil {
-		t.Errorf("expected 'string' to pack to nil. got %x instead", packed)
-	}
 }
diff --git a/accounts/abi/reflect.go b/accounts/abi/reflect.go
index 8fa75df07..e953b77c1 100644
--- a/accounts/abi/reflect.go
+++ b/accounts/abi/reflect.go
@@ -24,7 +24,7 @@ import (
 // indirect recursively dereferences the value until it either gets the value
 // or finds a big.Int
 func indirect(v reflect.Value) reflect.Value {
-	if v.Kind() == reflect.Ptr && v.Elem().Type() != big_t {
+	if v.Kind() == reflect.Ptr && v.Elem().Type() != derefbig_t {
 		return indirect(v.Elem())
 	}
 	return v
@@ -73,15 +73,9 @@ func mustArrayToByteSlice(value reflect.Value) reflect.Value {
 func set(dst, src reflect.Value, output Argument) error {
 	dstType := dst.Type()
 	srcType := src.Type()
-
 	switch {
-	case dstType.AssignableTo(src.Type()):
+	case dstType.AssignableTo(srcType):
 		dst.Set(src)
-	case dstType.Kind() == reflect.Array && srcType.Kind() == reflect.Slice:
-		if dst.Len() < output.Type.SliceSize {
-			return fmt.Errorf("abi: cannot unmarshal src (len=%d) in to dst (len=%d)", output.Type.SliceSize, dst.Len())
-		}
-		reflect.Copy(dst, src)
 	case dstType.Kind() == reflect.Interface:
 		dst.Set(src)
 	case dstType.Kind() == reflect.Ptr:
diff --git a/accounts/abi/type.go b/accounts/abi/type.go
index 5f20babb3..fba10b96d 100644
--- a/accounts/abi/type.go
+++ b/accounts/abi/type.go
@@ -21,6 +21,7 @@ import (
 	"reflect"
 	"regexp"
 	"strconv"
+	"strings"
 )
 
 const (
@@ -29,6 +30,7 @@ const (
 	BoolTy
 	StringTy
 	SliceTy
+	ArrayTy
 	AddressTy
 	FixedBytesTy
 	BytesTy
@@ -39,9 +41,6 @@ const (
 
 // Type is the reflection of the supported argument type
 type Type struct {
-	IsSlice, IsArray bool
-	SliceSize        int
-
 	Elem *Type
 
 	Kind reflect.Kind
@@ -53,118 +52,116 @@ type Type struct {
 }
 
 var (
-	// fullTypeRegex parses the abi types
-	//
-	// Types can be in the format of:
-	//
-	// 	Input  = Type [ "[" [ Number ] "]" ] Name .
-	// 	Type   = [ "u" ] "int" [ Number ] [ x ] [ Number ].
-	//
-	// Examples:
-	//
-	//      string     int       uint       fixed
-	//      string32   int8      uint8      uint[]
-	//      address    int256    uint256    fixed128x128[2]
-	fullTypeRegex = regexp.MustCompile(`([a-zA-Z0-9]+)(\[([0-9]*)\])?`)
 	// typeRegex parses the abi sub types
 	typeRegex = regexp.MustCompile("([a-zA-Z]+)(([0-9]+)(x([0-9]+))?)?")
 )
 
 // NewType creates a new reflection type of abi type given in t.
 func NewType(t string) (typ Type, err error) {
-	res := fullTypeRegex.FindAllStringSubmatch(t, -1)[0]
-	// check if type is slice and parse type.
-	switch {
-	case res[3] != "":
-		// err is ignored. Already checked for number through the regexp
-		typ.SliceSize, _ = strconv.Atoi(res[3])
-		typ.IsArray = true
-	case res[2] != "":
-		typ.IsSlice, typ.SliceSize = true, -1
-	case res[0] == "":
-		return Type{}, fmt.Errorf("abi: type parse error: %s", t)
+	// check that array brackets are equal if they exist
+	if strings.Count(t, "[") != strings.Count(t, "]") {
+		return Type{}, fmt.Errorf("invalid arg type in abi")
 	}
-	if typ.IsArray || typ.IsSlice {
-		sliceType, err := NewType(res[1])
+
+	typ.stringKind = t
+
+	// if there are brackets, get ready to go into slice/array mode and
+	// recursively create the type
+	if strings.Count(t, "[") != 0 {
+		i := strings.LastIndex(t, "[")
+		// recursively embed the type
+		embeddedType, err := NewType(t[:i])
 		if err != nil {
 			return Type{}, err
 		}
-		typ.Elem = &sliceType
-		typ.stringKind = sliceType.stringKind + t[len(res[1]):]
-		// Although we know that this is an array, we cannot return
-		// as we don't know the type of the element, however, if it
-		// is still an array, then don't determine the type.
-		if typ.Elem.IsArray || typ.Elem.IsSlice {
-			return typ, nil
-		}
-	}
-
-	// parse the type and size of the abi-type.
-	parsedType := typeRegex.FindAllStringSubmatch(res[1], -1)[0]
-	// varSize is the size of the variable
-	var varSize int
-	if len(parsedType[3]) > 0 {
-		var err error
-		varSize, err = strconv.Atoi(parsedType[2])
-		if err != nil {
-			return Type{}, fmt.Errorf("abi: error parsing variable size: %v", err)
+		// grab the last cell and create a type from there
+		sliced := t[i:]
+		// grab the slice size with regexp
+		re := regexp.MustCompile("[0-9]+")
+		intz := re.FindAllString(sliced, -1)
+
+		if len(intz) == 0 {
+			// is a slice
+			typ.T = SliceTy
+			typ.Kind = reflect.Slice
+			typ.Elem = &embeddedType
+			typ.Type = reflect.SliceOf(embeddedType.Type)
+		} else if len(intz) == 1 {
+			// is a array
+			typ.T = ArrayTy
+			typ.Kind = reflect.Array
+			typ.Elem = &embeddedType
+			typ.Size, err = strconv.Atoi(intz[0])
+			if err != nil {
+				return Type{}, fmt.Errorf("abi: error parsing variable size: %v", err)
+			}
+			typ.Type = reflect.ArrayOf(typ.Size, embeddedType.Type)
+		} else {
+			return Type{}, fmt.Errorf("invalid formatting of array type")
 		}
-	}
-	// varType is the parsed abi type
-	varType := parsedType[1]
-	// substitute canonical integer
-	if varSize == 0 && (varType == "int" || varType == "uint") {
-		varSize = 256
-		t += "256"
-	}
-
-	// only set stringKind if not array or slice, as for those,
-	// the correct string type has been set
-	if !(typ.IsArray || typ.IsSlice) {
-		typ.stringKind = t
-	}
-
-	switch varType {
-	case "int":
-		typ.Kind, typ.Type = reflectIntKindAndType(false, varSize)
-		typ.Size = varSize
-		typ.T = IntTy
-	case "uint":
-		typ.Kind, typ.Type = reflectIntKindAndType(true, varSize)
-		typ.Size = varSize
-		typ.T = UintTy
-	case "bool":
-		typ.Kind = reflect.Bool
-		typ.T = BoolTy
-	case "address":
-		typ.Kind = reflect.Array
-		typ.Type = address_t
-		typ.Size = 20
-		typ.T = AddressTy
-	case "string":
-		typ.Kind = reflect.String
-		typ.Size = -1
-		typ.T = StringTy
-	case "bytes":
-		sliceType, _ := NewType("uint8")
-		typ.Elem = &sliceType
-		if varSize == 0 {
-			typ.IsSlice = true
-			typ.T = BytesTy
-			typ.SliceSize = -1
+		return typ, err
+	} else {
+		// parse the type and size of the abi-type.
+		parsedType := typeRegex.FindAllStringSubmatch(t, -1)[0]
+		// varSize is the size of the variable
+		var varSize int
+		if len(parsedType[3]) > 0 {
+			var err error
+			varSize, err = strconv.Atoi(parsedType[2])
+			if err != nil {
+				return Type{}, fmt.Errorf("abi: error parsing variable size: %v", err)
+			}
 		} else {
-			typ.IsArray = true
-			typ.T = FixedBytesTy
-			typ.SliceSize = varSize
+			if parsedType[0] == "uint" || parsedType[0] == "int" {
+				// this should fail because it means that there's something wrong with
+				// the abi type (the compiler should always format it to the size...always)
+				return Type{}, fmt.Errorf("unsupported arg type: %s", t)
+			}
+		}
+		// varType is the parsed abi type
+		varType := parsedType[1]
+
+		switch varType {
+		case "int":
+			typ.Kind, typ.Type = reflectIntKindAndType(false, varSize)
+			typ.Size = varSize
+			typ.T = IntTy
+		case "uint":
+			typ.Kind, typ.Type = reflectIntKindAndType(true, varSize)
+			typ.Size = varSize
+			typ.T = UintTy
+		case "bool":
+			typ.Kind = reflect.Bool
+			typ.T = BoolTy
+			typ.Type = reflect.TypeOf(bool(false))
+		case "address":
+			typ.Kind = reflect.Array
+			typ.Type = address_t
+			typ.Size = 20
+			typ.T = AddressTy
+		case "string":
+			typ.Kind = reflect.String
+			typ.Type = reflect.TypeOf("")
+			typ.T = StringTy
+		case "bytes":
+			if varSize == 0 {
+				typ.T = BytesTy
+				typ.Kind = reflect.Slice
+				typ.Type = reflect.SliceOf(reflect.TypeOf(byte(0)))
+			} else {
+				typ.T = FixedBytesTy
+				typ.Kind = reflect.Array
+				typ.Size = varSize
+				typ.Type = reflect.ArrayOf(varSize, reflect.TypeOf(byte(0)))
+			}
+		case "function":
+			typ.Kind = reflect.Array
+			typ.T = FunctionTy
+			typ.Size = 24
+			typ.Type = reflect.ArrayOf(24, reflect.TypeOf(byte(0)))
+		default:
+			return Type{}, fmt.Errorf("unsupported arg type: %s", t)
 		}
-	case "function":
-		sliceType, _ := NewType("uint8")
-		typ.Elem = &sliceType
-		typ.IsArray = true
-		typ.T = FunctionTy
-		typ.SliceSize = 24
-	default:
-		return Type{}, fmt.Errorf("unsupported arg type: %s", t)
 	}
 
 	return
@@ -183,7 +180,7 @@ func (t Type) pack(v reflect.Value) ([]byte, error) {
 		return nil, err
 	}
 
-	if (t.IsSlice || t.IsArray) && t.T != BytesTy && t.T != FixedBytesTy && t.T != FunctionTy {
+	if t.T == SliceTy || t.T == ArrayTy {
 		var packed []byte
 
 		for i := 0; i < v.Len(); i++ {
@@ -193,18 +190,17 @@ func (t Type) pack(v reflect.Value) ([]byte, error) {
 			}
 			packed = append(packed, val...)
 		}
-		if t.IsSlice {
+		if t.T == SliceTy {
 			return packBytesSlice(packed, v.Len()), nil
-		} else if t.IsArray {
+		} else if t.T == ArrayTy {
 			return packed, nil
 		}
 	}
-
 	return packElement(t, v), nil
 }
 
 // requireLengthPrefix returns whether the type requires any sort of length
 // prefixing.
 func (t Type) requiresLengthPrefix() bool {
-	return t.T != FixedBytesTy && (t.T == StringTy || t.T == BytesTy || t.IsSlice)
+	return t.T == StringTy || t.T == BytesTy || t.T == SliceTy
 }
diff --git a/accounts/abi/type_test.go b/accounts/abi/type_test.go
index 984a5bb4c..e55af1293 100644
--- a/accounts/abi/type_test.go
+++ b/accounts/abi/type_test.go
@@ -21,6 +21,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/davecgh/go-spew/spew"
 	"github.com/ethereum/go-ethereum/common"
 )
 
@@ -34,51 +35,58 @@ func TestTypeRegexp(t *testing.T) {
 		blob string
 		kind Type
 	}{
-		{"bool", Type{Kind: reflect.Bool, T: BoolTy, stringKind: "bool"}},
-		{"bool[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Bool, T: BoolTy, Elem: &Type{Kind: reflect.Bool, T: BoolTy, stringKind: "bool"}, stringKind: "bool[]"}},
-		{"bool[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Bool, T: BoolTy, Elem: &Type{Kind: reflect.Bool, T: BoolTy, stringKind: "bool"}, stringKind: "bool[2]"}},
+		{"bool", Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}},
+		{"bool[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]bool(nil)), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[]"}},
+		{"bool[2]", Type{Size: 2, Kind: reflect.Array, T: ArrayTy, Type: reflect.TypeOf([2]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[2]"}},
+		{"bool[2][]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([][2]bool{}), Elem: &Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[2]"}, stringKind: "bool[2][]"}},
+		{"bool[][]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([][]bool{}), Elem: &Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[]"}, stringKind: "bool[][]"}},
+		{"bool[][2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][]bool{}), Elem: &Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[]"}, stringKind: "bool[][2]"}},
+		{"bool[2][2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][2]bool{}), Elem: &Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[2]"}, stringKind: "bool[2][2]"}},
+		{"bool[2][][2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][][2]bool{}), Elem: &Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([][2]bool{}), Elem: &Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[2]"}, stringKind: "bool[2][]"}, stringKind: "bool[2][][2]"}},
+		{"bool[2][2][2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][2][2]bool{}), Elem: &Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][2]bool{}), Elem: &Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[2]"}, stringKind: "bool[2][2]"}, stringKind: "bool[2][2][2]"}},
+		{"bool[][][]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([][][]bool{}), Elem: &Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([][]bool{}), Elem: &Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[]"}, stringKind: "bool[][]"}, stringKind: "bool[][][]"}},
+		{"bool[][2][]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([][2][]bool{}), Elem: &Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][]bool{}), Elem: &Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]bool{}), Elem: &Type{Kind: reflect.Bool, T: BoolTy, Type: reflect.TypeOf(bool(false)), stringKind: "bool"}, stringKind: "bool[]"}, stringKind: "bool[][2]"}, stringKind: "bool[][2][]"}},
 		{"int8", Type{Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, stringKind: "int8"}},
 		{"int16", Type{Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, stringKind: "int16"}},
 		{"int32", Type{Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, stringKind: "int32"}},
 		{"int64", Type{Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, stringKind: "int64"}},
 		{"int256", Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, stringKind: "int256"}},
-		{"int8[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, Elem: &Type{Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, stringKind: "int8"}, stringKind: "int8[]"}},
-		{"int8[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, Elem: &Type{Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, stringKind: "int8"}, stringKind: "int8[2]"}},
-		{"int16[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, Elem: &Type{Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, stringKind: "int16"}, stringKind: "int16[]"}},
-		{"int16[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, Elem: &Type{Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, stringKind: "int16"}, stringKind: "int16[2]"}},
-		{"int32[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, Elem: &Type{Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, stringKind: "int32"}, stringKind: "int32[]"}},
-		{"int32[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, Elem: &Type{Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, stringKind: "int32"}, stringKind: "int32[2]"}},
-		{"int64[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, Elem: &Type{Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, stringKind: "int64"}, stringKind: "int64[]"}},
-		{"int64[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, Elem: &Type{Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, stringKind: "int64"}, stringKind: "int64[2]"}},
-		{"int256[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, stringKind: "int256"}, stringKind: "int256[]"}},
-		{"int256[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, stringKind: "int256"}, stringKind: "int256[2]"}},
+		{"int8[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]int8{}), Elem: &Type{Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, stringKind: "int8"}, stringKind: "int8[]"}},
+		{"int8[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]int8{}), Elem: &Type{Kind: reflect.Int8, Type: int8_t, Size: 8, T: IntTy, stringKind: "int8"}, stringKind: "int8[2]"}},
+		{"int16[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]int16{}), Elem: &Type{Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, stringKind: "int16"}, stringKind: "int16[]"}},
+		{"int16[2]", Type{Size: 2, Kind: reflect.Array, T: ArrayTy, Type: reflect.TypeOf([2]int16{}), Elem: &Type{Kind: reflect.Int16, Type: int16_t, Size: 16, T: IntTy, stringKind: "int16"}, stringKind: "int16[2]"}},
+		{"int32[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]int32{}), Elem: &Type{Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, stringKind: "int32"}, stringKind: "int32[]"}},
+		{"int32[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]int32{}), Elem: &Type{Kind: reflect.Int32, Type: int32_t, Size: 32, T: IntTy, stringKind: "int32"}, stringKind: "int32[2]"}},
+		{"int64[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]int64{}), Elem: &Type{Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, stringKind: "int64"}, stringKind: "int64[]"}},
+		{"int64[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]int64{}), Elem: &Type{Kind: reflect.Int64, Type: int64_t, Size: 64, T: IntTy, stringKind: "int64"}, stringKind: "int64[2]"}},
+		{"int256[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]*big.Int{}), Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, stringKind: "int256"}, stringKind: "int256[]"}},
+		{"int256[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]*big.Int{}), Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: IntTy, stringKind: "int256"}, stringKind: "int256[2]"}},
 		{"uint8", Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}},
 		{"uint16", Type{Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, stringKind: "uint16"}},
 		{"uint32", Type{Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, stringKind: "uint32"}},
 		{"uint64", Type{Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, stringKind: "uint64"}},
 		{"uint256", Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, stringKind: "uint256"}},
-		{"uint8[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, stringKind: "uint8[]"}},
-		{"uint8[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, stringKind: "uint8[2]"}},
-		{"uint16[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, Elem: &Type{Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, stringKind: "uint16"}, stringKind: "uint16[]"}},
-		{"uint16[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, Elem: &Type{Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, stringKind: "uint16"}, stringKind: "uint16[2]"}},
-		{"uint32[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, Elem: &Type{Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, stringKind: "uint32"}, stringKind: "uint32[]"}},
-		{"uint32[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, Elem: &Type{Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, stringKind: "uint32"}, stringKind: "uint32[2]"}},
-		{"uint64[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, Elem: &Type{Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, stringKind: "uint64"}, stringKind: "uint64[]"}},
-		{"uint64[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, Elem: &Type{Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, stringKind: "uint64"}, stringKind: "uint64[2]"}},
-		{"uint256[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, stringKind: "uint256"}, stringKind: "uint256[]"}},
-		{"uint256[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, stringKind: "uint256"}, stringKind: "uint256[2]"}},
-		{"bytes32", Type{IsArray: true, SliceSize: 32, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, T: FixedBytesTy, stringKind: "bytes32"}},
-		{"bytes[]", Type{IsSlice: true, SliceSize: -1, Elem: &Type{IsSlice: true, SliceSize: -1, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, T: BytesTy, stringKind: "bytes"}, stringKind: "bytes[]"}},
-		{"bytes[2]", Type{IsArray: true, SliceSize: 2, Elem: &Type{IsSlice: true, SliceSize: -1, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, T: BytesTy, stringKind: "bytes"}, stringKind: "bytes[2]"}},
-		{"bytes32[]", Type{IsSlice: true, SliceSize: -1, Elem: &Type{IsArray: true, SliceSize: 32, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, T: FixedBytesTy, stringKind: "bytes32"}, stringKind: "bytes32[]"}},
-		{"bytes32[2]", Type{IsArray: true, SliceSize: 2, Elem: &Type{IsArray: true, SliceSize: 32, Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, T: FixedBytesTy, stringKind: "bytes32"}, stringKind: "bytes32[2]"}},
-		{"string", Type{Kind: reflect.String, Size: -1, T: StringTy, stringKind: "string"}},
-		{"string[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.String, T: StringTy, Size: -1, Elem: &Type{Kind: reflect.String, T: StringTy, Size: -1, stringKind: "string"}, stringKind: "string[]"}},
-		{"string[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.String, T: StringTy, Size: -1, Elem: &Type{Kind: reflect.String, T: StringTy, Size: -1, stringKind: "string"}, stringKind: "string[2]"}},
+		{"uint8[]", Type{Kind: reflect.Slice, T: SliceTy, Type: reflect.TypeOf([]uint8{}), Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, stringKind: "uint8[]"}},
+		{"uint8[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]uint8{}), Elem: &Type{Kind: reflect.Uint8, Type: uint8_t, Size: 8, T: UintTy, stringKind: "uint8"}, stringKind: "uint8[2]"}},
+		{"uint16[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]uint16{}), Elem: &Type{Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, stringKind: "uint16"}, stringKind: "uint16[]"}},
+		{"uint16[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]uint16{}), Elem: &Type{Kind: reflect.Uint16, Type: uint16_t, Size: 16, T: UintTy, stringKind: "uint16"}, stringKind: "uint16[2]"}},
+		{"uint32[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]uint32{}), Elem: &Type{Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, stringKind: "uint32"}, stringKind: "uint32[]"}},
+		{"uint32[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]uint32{}), Elem: &Type{Kind: reflect.Uint32, Type: uint32_t, Size: 32, T: UintTy, stringKind: "uint32"}, stringKind: "uint32[2]"}},
+		{"uint64[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]uint64{}), Elem: &Type{Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, stringKind: "uint64"}, stringKind: "uint64[]"}},
+		{"uint64[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]uint64{}), Elem: &Type{Kind: reflect.Uint64, Type: uint64_t, Size: 64, T: UintTy, stringKind: "uint64"}, stringKind: "uint64[2]"}},
+		{"uint256[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]*big.Int{}), Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, stringKind: "uint256"}, stringKind: "uint256[]"}},
+		{"uint256[2]", Type{Kind: reflect.Array, T: ArrayTy, Type: reflect.TypeOf([2]*big.Int{}), Size: 2, Elem: &Type{Kind: reflect.Ptr, Type: big_t, Size: 256, T: UintTy, stringKind: "uint256"}, stringKind: "uint256[2]"}},
+		{"bytes32", Type{Kind: reflect.Array, T: FixedBytesTy, Size: 32, Type: reflect.TypeOf([32]byte{}), stringKind: "bytes32"}},
+		{"bytes[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([][]byte{}), Elem: &Type{Kind: reflect.Slice, Type: reflect.TypeOf([]byte{}), T: BytesTy, stringKind: "bytes"}, stringKind: "bytes[]"}},
+		{"bytes[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][]byte{}), Elem: &Type{T: BytesTy, Type: reflect.TypeOf([]byte{}), Kind: reflect.Slice, stringKind: "bytes"}, stringKind: "bytes[2]"}},
+		{"bytes32[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([][32]byte{}), Elem: &Type{Kind: reflect.Array, Type: reflect.TypeOf([32]byte{}), T: FixedBytesTy, Size: 32, stringKind: "bytes32"}, stringKind: "bytes32[]"}},
+		{"bytes32[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2][32]byte{}), Elem: &Type{Kind: reflect.Array, T: FixedBytesTy, Size: 32, Type: reflect.TypeOf([32]byte{}), stringKind: "bytes32"}, stringKind: "bytes32[2]"}},
+		{"string", Type{Kind: reflect.String, T: StringTy, Type: reflect.TypeOf(""), stringKind: "string"}},
+		{"string[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]string{}), Elem: &Type{Kind: reflect.String, Type: reflect.TypeOf(""), T: StringTy, stringKind: "string"}, stringKind: "string[]"}},
+		{"string[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]string{}), Elem: &Type{Kind: reflect.String, T: StringTy, Type: reflect.TypeOf(""), stringKind: "string"}, stringKind: "string[2]"}},
 		{"address", Type{Kind: reflect.Array, Type: address_t, Size: 20, T: AddressTy, stringKind: "address"}},
-		{"address[]", Type{IsSlice: true, SliceSize: -1, Kind: reflect.Array, Type: address_t, T: AddressTy, Size: 20, Elem: &Type{Kind: reflect.Array, Type: address_t, Size: 20, T: AddressTy, stringKind: "address"}, stringKind: "address[]"}},
-		{"address[2]", Type{IsArray: true, SliceSize: 2, Kind: reflect.Array, Type: address_t, T: AddressTy, Size: 20, Elem: &Type{Kind: reflect.Array, Type: address_t, Size: 20, T: AddressTy, stringKind: "address"}, stringKind: "address[2]"}},
-
+		{"address[]", Type{T: SliceTy, Kind: reflect.Slice, Type: reflect.TypeOf([]common.Address{}), Elem: &Type{Kind: reflect.Array, Type: address_t, Size: 20, T: AddressTy, stringKind: "address"}, stringKind: "address[]"}},
+		{"address[2]", Type{Kind: reflect.Array, T: ArrayTy, Size: 2, Type: reflect.TypeOf([2]common.Address{}), Elem: &Type{Kind: reflect.Array, Type: address_t, Size: 20, T: AddressTy, stringKind: "address"}, stringKind: "address[2]"}},
 		// TODO when fixed types are implemented properly
 		// {"fixed", Type{}},
 		// {"fixed128x128", Type{}},
@@ -87,13 +95,14 @@ func TestTypeRegexp(t *testing.T) {
 		// {"fixed128x128[]", Type{}},
 		// {"fixed128x128[2]", Type{}},
 	}
-	for i, tt := range tests {
+
+	for _, tt := range tests {
 		typ, err := NewType(tt.blob)
 		if err != nil {
-			t.Errorf("type %d: failed to parse type string: %v", i, err)
+			t.Errorf("type %q: failed to parse type string: %v", tt.blob, err)
 		}
 		if !reflect.DeepEqual(typ, tt.kind) {
-			t.Errorf("type %d: parsed type mismatch:\n  have %+v\n  want %+v", i, typeWithoutStringer(typ), typeWithoutStringer(tt.kind))
+			t.Errorf("type %q: parsed type mismatch:\nGOT %s\nWANT %s ", tt.blob, spew.Sdump(typeWithoutStringer(typ)), spew.Sdump(typeWithoutStringer(tt.kind)))
 		}
 	}
 }
@@ -104,15 +113,90 @@ func TestTypeCheck(t *testing.T) {
 		input interface{}
 		err   string
 	}{
-		{"uint", big.NewInt(1), ""},
-		{"int", big.NewInt(1), ""},
-		{"uint30", big.NewInt(1), ""},
+		{"uint", big.NewInt(1), "unsupported arg type: uint"},
+		{"int", big.NewInt(1), "unsupported arg type: int"},
+		{"uint256", big.NewInt(1), ""},
+		{"uint256[][3][]", [][3][]*big.Int{{{}}}, ""},
+		{"uint256[][][3]", [3][][]*big.Int{{{}}}, ""},
+		{"uint256[3][][]", [][][3]*big.Int{{{}}}, ""},
+		{"uint256[3][3][3]", [3][3][3]*big.Int{{{}}}, ""},
+		{"uint8[][]", [][]uint8{}, ""},
+		{"int256", big.NewInt(1), ""},
+		{"uint8", uint8(1), ""},
+		{"uint16", uint16(1), ""},
+		{"uint32", uint32(1), ""},
+		{"uint64", uint64(1), ""},
+		{"int8", int8(1), ""},
+		{"int16", int16(1), ""},
+		{"int32", int32(1), ""},
+		{"int64", int64(1), ""},
+		{"uint24", big.NewInt(1), ""},
+		{"uint40", big.NewInt(1), ""},
+		{"uint48", big.NewInt(1), ""},
+		{"uint56", big.NewInt(1), ""},
+		{"uint72", big.NewInt(1), ""},
+		{"uint80", big.NewInt(1), ""},
+		{"uint88", big.NewInt(1), ""},
+		{"uint96", big.NewInt(1), ""},
+		{"uint104", big.NewInt(1), ""},
+		{"uint112", big.NewInt(1), ""},
+		{"uint120", big.NewInt(1), ""},
+		{"uint128", big.NewInt(1), ""},
+		{"uint136", big.NewInt(1), ""},
+		{"uint144", big.NewInt(1), ""},
+		{"uint152", big.NewInt(1), ""},
+		{"uint160", big.NewInt(1), ""},
+		{"uint168", big.NewInt(1), ""},
+		{"uint176", big.NewInt(1), ""},
+		{"uint184", big.NewInt(1), ""},
+		{"uint192", big.NewInt(1), ""},
+		{"uint200", big.NewInt(1), ""},
+		{"uint208", big.NewInt(1), ""},
+		{"uint216", big.NewInt(1), ""},
+		{"uint224", big.NewInt(1), ""},
+		{"uint232", big.NewInt(1), ""},
+		{"uint240", big.NewInt(1), ""},
+		{"uint248", big.NewInt(1), ""},
+		{"int24", big.NewInt(1), ""},
+		{"int40", big.NewInt(1), ""},
+		{"int48", big.NewInt(1), ""},
+		{"int56", big.NewInt(1), ""},
+		{"int72", big.NewInt(1), ""},
+		{"int80", big.NewInt(1), ""},
+		{"int88", big.NewInt(1), ""},
+		{"int96", big.NewInt(1), ""},
+		{"int104", big.NewInt(1), ""},
+		{"int112", big.NewInt(1), ""},
+		{"int120", big.NewInt(1), ""},
+		{"int128", big.NewInt(1), ""},
+		{"int136", big.NewInt(1), ""},
+		{"int144", big.NewInt(1), ""},
+		{"int152", big.NewInt(1), ""},
+		{"int160", big.NewInt(1), ""},
+		{"int168", big.NewInt(1), ""},
+		{"int176", big.NewInt(1), ""},
+		{"int184", big.NewInt(1), ""},
+		{"int192", big.NewInt(1), ""},
+		{"int200", big.NewInt(1), ""},
+		{"int208", big.NewInt(1), ""},
+		{"int216", big.NewInt(1), ""},
+		{"int224", big.NewInt(1), ""},
+		{"int232", big.NewInt(1), ""},
+		{"int240", big.NewInt(1), ""},
+		{"int248", big.NewInt(1), ""},
 		{"uint30", uint8(1), "abi: cannot use uint8 as type ptr as argument"},
+		{"uint8", uint16(1), "abi: cannot use uint16 as type uint8 as argument"},
+		{"uint8", uint32(1), "abi: cannot use uint32 as type uint8 as argument"},
+		{"uint8", uint64(1), "abi: cannot use uint64 as type uint8 as argument"},
+		{"uint8", int8(1), "abi: cannot use int8 as type uint8 as argument"},
+		{"uint8", int16(1), "abi: cannot use int16 as type uint8 as argument"},
+		{"uint8", int32(1), "abi: cannot use int32 as type uint8 as argument"},
+		{"uint8", int64(1), "abi: cannot use int64 as type uint8 as argument"},
 		{"uint16", uint16(1), ""},
 		{"uint16", uint8(1), "abi: cannot use uint8 as type uint16 as argument"},
 		{"uint16[]", []uint16{1, 2, 3}, ""},
 		{"uint16[]", [3]uint16{1, 2, 3}, ""},
-		{"uint16[]", []uint32{1, 2, 3}, "abi: cannot use []uint32 as type []uint16 as argument"},
+		{"uint16[]", []uint32{1, 2, 3}, "abi: cannot use []uint32 as type [0]uint16 as argument"},
 		{"uint16[3]", [3]uint32{1, 2, 3}, "abi: cannot use [3]uint32 as type [3]uint16 as argument"},
 		{"uint16[3]", [4]uint16{1, 2, 3}, "abi: cannot use [4]uint16 as type [3]uint16 as argument"},
 		{"uint16[3]", []uint16{1, 2, 3}, ""},
@@ -122,20 +206,61 @@ func TestTypeCheck(t *testing.T) {
 		{"address[1]", [1]common.Address{{1}}, ""},
 		{"address[2]", [1]common.Address{{1}}, "abi: cannot use [1]array as type [2]array as argument"},
 		{"bytes32", [32]byte{}, ""},
+		{"bytes31", [31]byte{}, ""},
+		{"bytes30", [30]byte{}, ""},
+		{"bytes29", [29]byte{}, ""},
+		{"bytes28", [28]byte{}, ""},
+		{"bytes27", [27]byte{}, ""},
+		{"bytes26", [26]byte{}, ""},
+		{"bytes25", [25]byte{}, ""},
+		{"bytes24", [24]byte{}, ""},
+		{"bytes23", [23]byte{}, ""},
+		{"bytes22", [22]byte{}, ""},
+		{"bytes21", [21]byte{}, ""},
+		{"bytes20", [20]byte{}, ""},
+		{"bytes19", [19]byte{}, ""},
+		{"bytes18", [18]byte{}, ""},
+		{"bytes17", [17]byte{}, ""},
+		{"bytes16", [16]byte{}, ""},
+		{"bytes15", [15]byte{}, ""},
+		{"bytes14", [14]byte{}, ""},
+		{"bytes13", [13]byte{}, ""},
+		{"bytes12", [12]byte{}, ""},
+		{"bytes11", [11]byte{}, ""},
+		{"bytes10", [10]byte{}, ""},
+		{"bytes9", [9]byte{}, ""},
+		{"bytes8", [8]byte{}, ""},
+		{"bytes7", [7]byte{}, ""},
+		{"bytes6", [6]byte{}, ""},
+		{"bytes5", [5]byte{}, ""},
+		{"bytes4", [4]byte{}, ""},
+		{"bytes3", [3]byte{}, ""},
+		{"bytes2", [2]byte{}, ""},
+		{"bytes1", [1]byte{}, ""},
 		{"bytes32", [33]byte{}, "abi: cannot use [33]uint8 as type [32]uint8 as argument"},
 		{"bytes32", common.Hash{1}, ""},
-		{"bytes31", [31]byte{}, ""},
+		{"bytes31", common.Hash{1}, "abi: cannot use common.Hash as type [31]uint8 as argument"},
 		{"bytes31", [32]byte{}, "abi: cannot use [32]uint8 as type [31]uint8 as argument"},
 		{"bytes", []byte{0, 1}, ""},
-		{"bytes", [2]byte{0, 1}, ""},
-		{"bytes", common.Hash{1}, ""},
+		{"bytes", [2]byte{0, 1}, "abi: cannot use array as type slice as argument"},
+		{"bytes", common.Hash{1}, "abi: cannot use array as type slice as argument"},
 		{"string", "hello world", ""},
+		{"string", string(""), ""},
+		{"string", []byte{}, "abi: cannot use slice as type string as argument"},
 		{"bytes32[]", [][32]byte{{}}, ""},
 		{"function", [24]byte{}, ""},
+		{"bytes20", common.Address{}, ""},
+		{"address", [20]byte{}, ""},
+		{"address", common.Address{}, ""},
 	} {
 		typ, err := NewType(test.typ)
-		if err != nil {
+		if err != nil && len(test.err) == 0 {
 			t.Fatal("unexpected parse error:", err)
+		} else if err != nil && len(test.err) != 0 {
+			if err.Error() != test.err {
+				t.Errorf("%d failed. Expected err: '%v' got err: '%v'", i, test.err, err)
+			}
+			continue
 		}
 
 		err = typeCheck(typ, reflect.ValueOf(test.input))
diff --git a/accounts/abi/unpack.go b/accounts/abi/unpack.go
index fc41c88ac..57732797b 100644
--- a/accounts/abi/unpack.go
+++ b/accounts/abi/unpack.go
@@ -25,122 +25,20 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
-// toGoSliceType parses the input and casts it to the proper slice defined by the ABI
-// argument in T.
-func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
-	index := i * 32
-	// The slice must, at very least be large enough for the index+32 which is exactly the size required
-	// for the [offset in output, size of offset].
-	if index+32 > len(output) {
-		return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), index+32)
-	}
-	elem := t.Type.Elem
-
-	// first we need to create a slice of the type
-	var refSlice reflect.Value
-	switch elem.T {
-	case IntTy, UintTy, BoolTy:
-		// create a new reference slice matching the element type
-		switch t.Type.Kind {
-		case reflect.Bool:
-			refSlice = reflect.ValueOf([]bool(nil))
-		case reflect.Uint8:
-			refSlice = reflect.ValueOf([]uint8(nil))
-		case reflect.Uint16:
-			refSlice = reflect.ValueOf([]uint16(nil))
-		case reflect.Uint32:
-			refSlice = reflect.ValueOf([]uint32(nil))
-		case reflect.Uint64:
-			refSlice = reflect.ValueOf([]uint64(nil))
-		case reflect.Int8:
-			refSlice = reflect.ValueOf([]int8(nil))
-		case reflect.Int16:
-			refSlice = reflect.ValueOf([]int16(nil))
-		case reflect.Int32:
-			refSlice = reflect.ValueOf([]int32(nil))
-		case reflect.Int64:
-			refSlice = reflect.ValueOf([]int64(nil))
-		default:
-			refSlice = reflect.ValueOf([]*big.Int(nil))
-		}
-	case AddressTy: // address must be of slice Address
-		refSlice = reflect.ValueOf([]common.Address(nil))
-	case HashTy: // hash must be of slice hash
-		refSlice = reflect.ValueOf([]common.Hash(nil))
-	case FixedBytesTy:
-		refSlice = reflect.ValueOf([][]byte(nil))
-	default: // no other types are supported
-		return nil, fmt.Errorf("abi: unsupported slice type %v", elem.T)
-	}
-
-	var slice []byte
-	var size int
-	var offset int
-	if t.Type.IsSlice {
-		// get the offset which determines the start of this array ...
-		offset = int(binary.BigEndian.Uint64(output[index+24 : index+32]))
-		if offset+32 > len(output) {
-			return nil, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
-		}
-
-		slice = output[offset:]
-		// ... starting with the size of the array in elements ...
-		size = int(binary.BigEndian.Uint64(slice[24:32]))
-		slice = slice[32:]
-		// ... and make sure that we've at the very least the amount of bytes
-		// available in the buffer.
-		if size*32 > len(slice) {
-			return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), offset+32+size*32)
-		}
-
-		// reslice to match the required size
-		slice = slice[:size*32]
-	} else if t.Type.IsArray {
-		//get the number of elements in the array
-		size = t.Type.SliceSize
-
-		//check to make sure array size matches up
-		if index+32*size > len(output) {
-			return nil, fmt.Errorf("abi: cannot marshal in to go array: offset %d would go over slice boundary (len=%d)", len(output), index+32*size)
-		}
-		//slice is there for a fixed amount of times
-		slice = output[index : index+size*32]
-	}
-
-	for i := 0; i < size; i++ {
-		var (
-			inter        interface{}             // interface type
-			returnOutput = slice[i*32 : i*32+32] // the return output
-			err          error
-		)
-		// set inter to the correct type (cast)
-		switch elem.T {
-		case IntTy, UintTy:
-			inter = readInteger(t.Type.Kind, returnOutput)
-		case BoolTy:
-			inter, err = readBool(returnOutput)
-			if err != nil {
-				return nil, err
-			}
-		case AddressTy:
-			inter = common.BytesToAddress(returnOutput)
-		case HashTy:
-			inter = common.BytesToHash(returnOutput)
-		case FixedBytesTy:
-			inter = returnOutput
-		}
-		// append the item to our reflect slice
-		refSlice = reflect.Append(refSlice, reflect.ValueOf(inter))
-	}
-
-	// return the interface
-	return refSlice.Interface(), nil
+// unpacker is a utility interface that enables us to have
+// abstraction between events and methods and also to properly
+// "unpack" them; e.g. events use Inputs, methods use Outputs.
+type unpacker interface {
+	tupleUnpack(v interface{}, output []byte) error
+	singleUnpack(v interface{}, output []byte) error
+	isTupleReturn() bool
 }
 
+// reads the integer based on its kind
 func readInteger(kind reflect.Kind, b []byte) interface{} {
 	switch kind {
 	case reflect.Uint8:
-		return uint8(b[len(b)-1])
+		return b[len(b)-1]
 	case reflect.Uint16:
 		return binary.BigEndian.Uint16(b[len(b)-2:])
 	case reflect.Uint32:
@@ -160,13 +58,10 @@ func readInteger(kind reflect.Kind, b []byte) interface{} {
 	}
 }
 
+// reads a bool
 func readBool(word []byte) (bool, error) {
-	if len(word) != 32 {
-		return false, fmt.Errorf("abi: fatal error: incorrect word length")
-	}
-
-	for i, b := range word {
-		if b != 0 && i != 31 {
+	for _, b := range word[:31] {
+		if b != 0 {
 			return false, errBadBool
 		}
 	}
@@ -178,58 +73,144 @@ func readBool(word []byte) (bool, error) {
 	default:
 		return false, errBadBool
 	}
+}
 
+// A function type is simply the address with the function selection signature at the end.
+// This enforces that standard by always presenting it as a 24-array (address + sig = 24 bytes)
+func readFunctionType(t Type, word []byte) (funcTy [24]byte, err error) {
+	if t.T != FunctionTy {
+		return [24]byte{}, fmt.Errorf("abi: invalid type in call to make function type byte array.")
+	}
+	if garbage := binary.BigEndian.Uint64(word[24:32]); garbage != 0 {
+		err = fmt.Errorf("abi: got improperly encoded function type, got %v", word)
+	} else {
+		copy(funcTy[:], word[0:24])
+	}
+	return
 }
 
-// toGoType parses the input and casts it to the proper type defined by the ABI
-// argument in T.
-func toGoType(i int, t Argument, output []byte) (interface{}, error) {
-	// we need to treat slices differently
-	if (t.Type.IsSlice || t.Type.IsArray) && t.Type.T != BytesTy && t.Type.T != StringTy && t.Type.T != FixedBytesTy && t.Type.T != FunctionTy {
-		return toGoSlice(i, t, output)
+// through reflection, creates a fixed array to be read from
+func readFixedBytes(t Type, word []byte) (interface{}, error) {
+	if t.T != FixedBytesTy {
+		return nil, fmt.Errorf("abi: invalid type in call to make fixed byte array.")
 	}
+	// convert
+	array := reflect.New(t.Type).Elem()
 
-	index := i * 32
-	if index+32 > len(output) {
-		return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
+	reflect.Copy(array, reflect.ValueOf(word[0:t.Size]))
+	return array.Interface(), nil
+
+}
+
+// iteratively unpack elements
+func forEachUnpack(t Type, output []byte, start, size int) (interface{}, error) {
+	if start+32*size > len(output) {
+		return nil, fmt.Errorf("abi: cannot marshal in to go array: offset %d would go over slice boundary (len=%d)", len(output), start+32*size)
 	}
 
-	// Parse the given index output and check whether we need to read
-	// a different offset and length based on the type (i.e. string, bytes)
-	var returnOutput []byte
-	switch t.Type.T {
-	case StringTy, BytesTy: // variable arrays are written at the end of the return bytes
-		// parse offset from which we should start reading
-		offset := int(binary.BigEndian.Uint64(output[index+24 : index+32]))
-		if offset+32 > len(output) {
-			return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32)
+	// this value will become our slice or our array, depending on the type
+	var refSlice reflect.Value
+	slice := output[start : start+size*32]
+
+	if t.T == SliceTy {
+		// declare our slice
+		refSlice = reflect.MakeSlice(t.Type, size, size)
+	} else if t.T == ArrayTy {
+		// declare our array
+		refSlice = reflect.New(t.Type).Elem()
+	} else {
+		return nil, fmt.Errorf("abi: invalid type in array/slice unpacking stage")
+	}
+
+	for i, j := start, 0; j*32 < len(slice); i, j = i+32, j+1 {
+		// this corrects the arrangement so that we get all the underlying array values
+		if t.Elem.T == ArrayTy && j != 0 {
+			i = start + t.Elem.Size*32*j
 		}
-		// parse the size up until we should be reading
-		size := int(binary.BigEndian.Uint64(output[offset+24 : offset+32]))
-		if offset+32+size > len(output) {
-			return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+size)
+		inter, err := toGoType(i, *t.Elem, output)
+		if err != nil {
+			return nil, err
 		}
+		// append the item to our reflect slice
+		refSlice.Index(j).Set(reflect.ValueOf(inter))
+	}
 
-		// get the bytes for this return value
-		returnOutput = output[offset+32 : offset+32+size]
-	default:
+	// return the interface
+	return refSlice.Interface(), nil
+}
+
+// toGoType parses the output bytes and recursively assigns the value of these bytes
+// into a go type with accordance with the ABI spec.
+func toGoType(index int, t Type, output []byte) (interface{}, error) {
+	if index+32 > len(output) {
+		return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
+	}
+
+	var (
+		returnOutput []byte
+		begin, end   int
+		err          error
+	)
+
+	// if we require a length prefix, find the beginning word and size returned.
+	if t.requiresLengthPrefix() {
+		begin, end, err = lengthPrefixPointsTo(index, output)
+		if err != nil {
+			return nil, err
+		}
+	} else {
 		returnOutput = output[index : index+32]
 	}
 
-	// convert the bytes to whatever is specified by the ABI.
-	switch t.Type.T {
+	switch t.T {
+	case SliceTy:
+		return forEachUnpack(t, output, begin, end)
+	case ArrayTy:
+		return forEachUnpack(t, output, index, t.Size)
+	case StringTy: // variable arrays are written at the end of the return bytes
+		return string(output[begin : begin+end]), nil
 	case IntTy, UintTy:
-		return readInteger(t.Type.Kind, returnOutput), nil
+		return readInteger(t.Kind, returnOutput), nil
 	case BoolTy:
 		return readBool(returnOutput)
 	case AddressTy:
 		return common.BytesToAddress(returnOutput), nil
 	case HashTy:
 		return common.BytesToHash(returnOutput), nil
-	case BytesTy, FixedBytesTy, FunctionTy:
-		return returnOutput, nil
-	case StringTy:
-		return string(returnOutput), nil
+	case BytesTy:
+		return output[begin : begin+end], nil
+	case FixedBytesTy:
+		return readFixedBytes(t, returnOutput)
+	case FunctionTy:
+		return readFunctionType(t, returnOutput)
+	default:
+		return nil, fmt.Errorf("abi: unknown type %v", t.T)
+	}
+}
+
+// interprets a 32 byte slice as an offset and then determines which indice to look to decode the type.
+func lengthPrefixPointsTo(index int, output []byte) (start int, length int, err error) {
+	offset := int(binary.BigEndian.Uint64(output[index+24 : index+32]))
+	if offset+32 > len(output) {
+		return 0, 0, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
+	}
+	length = int(binary.BigEndian.Uint64(output[offset+24 : offset+32]))
+	if offset+32+length > len(output) {
+		return 0, 0, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+length)
+	}
+	start = offset + 32
+
+	//fmt.Printf("LENGTH PREFIX INFO: \nsize: %v\noffset: %v\nstart: %v\n", length, offset, start)
+	return
+}
+
+// checks for proper formatting of byte output
+func bytesAreProper(output []byte) error {
+	if len(output) == 0 {
+		return fmt.Errorf("abi: unmarshalling empty output")
+	} else if len(output)%32 != 0 {
+		return fmt.Errorf("abi: improperly formatted output")
+	} else {
+		return nil
 	}
-	return nil, fmt.Errorf("abi: unknown type %v", t.Type.T)
 }
diff --git a/accounts/abi/unpack_test.go b/accounts/abi/unpack_test.go
index 8e3afee4e..1e21aafc0 100644
--- a/accounts/abi/unpack_test.go
+++ b/accounts/abi/unpack_test.go
@@ -18,6 +18,7 @@ package abi
 
 import (
 	"bytes"
+	"encoding/hex"
 	"fmt"
 	"math/big"
 	"reflect"
@@ -27,263 +28,261 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
-func TestSimpleMethodUnpack(t *testing.T) {
-	for i, test := range []struct {
-		def              string      // definition of the **output** ABI params
-		marshalledOutput []byte      // evm return data
-		expectedOut      interface{} // the expected output
-		outVar           string      // the output variable (e.g. uint32, *big.Int, etc)
-		err              string      // empty or error if expected
-	}{
-		{
-			`[ { "type": "bool" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			bool(true),
-			"bool",
-			"",
-		},
-		{
-			`[ { "type": "uint32" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			uint32(1),
-			"uint32",
-			"",
-		},
-		{
-			`[ { "type": "uint32" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			nil,
-			"uint16",
-			"abi: cannot unmarshal uint32 in to uint16",
-		},
-		{
-			`[ { "type": "uint17" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			nil,
-			"uint16",
-			"abi: cannot unmarshal *big.Int in to uint16",
-		},
-		{
-			`[ { "type": "uint17" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			big.NewInt(1),
-			"*big.Int",
-			"",
-		},
-
-		{
-			`[ { "type": "int32" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			int32(1),
-			"int32",
-			"",
-		},
-		{
-			`[ { "type": "int32" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			nil,
-			"int16",
-			"abi: cannot unmarshal int32 in to int16",
-		},
-		{
-			`[ { "type": "int17" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			nil,
-			"int16",
-			"abi: cannot unmarshal *big.Int in to int16",
-		},
-		{
-			`[ { "type": "int17" } ]`,
-			common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"),
-			big.NewInt(1),
-			"*big.Int",
-			"",
-		},
-
-		{
-			`[ { "type": "address" } ]`,
-			common.Hex2Bytes("0000000000000000000000000100000000000000000000000000000000000000"),
-			common.Address{1},
-			"address",
-			"",
-		},
-		{
-			`[ { "type": "bytes32" } ]`,
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			"bytes",
-			"",
-		},
-		{
-			`[ { "type": "bytes32" } ]`,
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			"hash",
-			"",
-		},
-		{
-			`[ { "type": "bytes32" } ]`,
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			"interface",
-			"",
-		},
-		{
-			`[ { "type": "function" } ]`,
-			common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
-			[24]byte{1},
-			"function",
-			"",
-		},
-	} {
-		abiDefinition := fmt.Sprintf(`[{ "name" : "method", "outputs": %s}]`, test.def)
-		abi, err := JSON(strings.NewReader(abiDefinition))
-		if err != nil {
-			t.Errorf("%d failed. %v", i, err)
-			continue
-		}
+type unpackTest struct {
+	def  string      // ABI definition JSON
+	enc  string      // evm return data
+	want interface{} // the expected output
+	err  string      // empty or error if expected
+}
 
-		var outvar interface{}
-		switch test.outVar {
-		case "bool":
-			var v bool
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "uint8":
-			var v uint8
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "uint16":
-			var v uint16
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "uint32":
-			var v uint32
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "uint64":
-			var v uint64
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "int8":
-			var v int8
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "int16":
-			var v int16
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "int32":
-			var v int32
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "int64":
-			var v int64
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "*big.Int":
-			var v *big.Int
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "address":
-			var v common.Address
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "bytes":
-			var v []byte
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "hash":
-			var v common.Hash
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v.Bytes()[:]
-		case "function":
-			var v [24]byte
-			err = abi.Unpack(&v, "method", test.marshalledOutput)
-			outvar = v
-		case "interface":
-			err = abi.Unpack(&outvar, "method", test.marshalledOutput)
-		default:
-			t.Errorf("unsupported type '%v' please add it to the switch statement in this test", test.outVar)
-			continue
+func (test unpackTest) checkError(err error) error {
+	if err != nil {
+		if len(test.err) == 0 {
+			return fmt.Errorf("expected no err but got: %v", err)
+		} else if err.Error() != test.err {
+			return fmt.Errorf("expected err: '%v' got err: %q", test.err, err)
 		}
+	} else if len(test.err) > 0 {
+		return fmt.Errorf("expected err: %v but got none", test.err)
+	}
+	return nil
+}
 
-		if err != nil && len(test.err) == 0 {
-			t.Errorf("%d failed. Expected no err but got: %v", i, err)
-			continue
+var unpackTests = []unpackTest{
+	{
+		def:  `[{ "type": "bool" }]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: true,
+	},
+	{
+		def:  `[{"type": "uint32"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: uint32(1),
+	},
+	{
+		def:  `[{"type": "uint32"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: uint16(0),
+		err:  "abi: cannot unmarshal uint32 in to uint16",
+	},
+	{
+		def:  `[{"type": "uint17"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: uint16(0),
+		err:  "abi: cannot unmarshal *big.Int in to uint16",
+	},
+	{
+		def:  `[{"type": "uint17"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: big.NewInt(1),
+	},
+	{
+		def:  `[{"type": "int32"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: int32(1),
+	},
+	{
+		def:  `[{"type": "int32"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: int16(0),
+		err:  "abi: cannot unmarshal int32 in to int16",
+	},
+	{
+		def:  `[{"type": "int17"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: int16(0),
+		err:  "abi: cannot unmarshal *big.Int in to int16",
+	},
+	{
+		def:  `[{"type": "int17"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001",
+		want: big.NewInt(1),
+	},
+	{
+		def:  `[{"type": "address"}]`,
+		enc:  "0000000000000000000000000100000000000000000000000000000000000000",
+		want: common.Address{1},
+	},
+	{
+		def:  `[{"type": "bytes32"}]`,
+		enc:  "0100000000000000000000000000000000000000000000000000000000000000",
+		want: [32]byte{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+	},
+	{
+		def:  `[{"type": "bytes"}]`,
+		enc:  "000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000200100000000000000000000000000000000000000000000000000000000000000",
+		want: common.Hex2Bytes("0100000000000000000000000000000000000000000000000000000000000000"),
+	},
+	{
+		def:  `[{"type": "bytes"}]`,
+		enc:  "000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000200100000000000000000000000000000000000000000000000000000000000000",
+		want: [32]byte{},
+		err:  "abi: cannot unmarshal []uint8 in to [32]uint8",
+	},
+	{
+		def:  `[{"type": "bytes32"}]`,
+		enc:  "000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000200100000000000000000000000000000000000000000000000000000000000000",
+		want: []byte(nil),
+		err:  "abi: cannot unmarshal [32]uint8 in to []uint8",
+	},
+	{
+		def:  `[{"type": "bytes32"}]`,
+		enc:  "0100000000000000000000000000000000000000000000000000000000000000",
+		want: common.HexToHash("0100000000000000000000000000000000000000000000000000000000000000"),
+	},
+	{
+		def:  `[{"type": "function"}]`,
+		enc:  "0100000000000000000000000000000000000000000000000000000000000000",
+		want: [24]byte{1},
+	},
+	// slices
+	{
+		def:  `[{"type": "uint8[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []uint8{1, 2},
+	},
+	{
+		def:  `[{"type": "uint8[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]uint8{1, 2},
+	},
+	// multi dimensional, if these pass, all types that don't require length prefix should pass
+	{
+		def:  `[{"type": "uint8[][]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000E0000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [][]uint8{{1, 2}, {1, 2}},
+	},
+	{
+		def:  `[{"type": "uint8[2][2]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2][2]uint8{{1, 2}, {1, 2}},
+	},
+	{
+		def:  `[{"type": "uint8[][2]"}]`,
+		enc:  "000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001",
+		want: [2][]uint8{{1}, {1}},
+	},
+	{
+		def:  `[{"type": "uint8[2][]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [][2]uint8{{1, 2}},
+	},
+	{
+		def:  `[{"type": "uint16[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []uint16{1, 2},
+	},
+	{
+		def:  `[{"type": "uint16[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]uint16{1, 2},
+	},
+	{
+		def:  `[{"type": "uint32[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []uint32{1, 2},
+	},
+	{
+		def:  `[{"type": "uint32[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]uint32{1, 2},
+	},
+	{
+		def:  `[{"type": "uint64[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []uint64{1, 2},
+	},
+	{
+		def:  `[{"type": "uint64[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]uint64{1, 2},
+	},
+	{
+		def:  `[{"type": "uint256[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []*big.Int{big.NewInt(1), big.NewInt(2)},
+	},
+	{
+		def:  `[{"type": "uint256[3]"}]`,
+		enc:  "000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000003",
+		want: [3]*big.Int{big.NewInt(1), big.NewInt(2), big.NewInt(3)},
+	},
+	{
+		def:  `[{"type": "int8[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []int8{1, 2},
+	},
+	{
+		def:  `[{"type": "int8[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]int8{1, 2},
+	},
+	{
+		def:  `[{"type": "int16[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []int16{1, 2},
+	},
+	{
+		def:  `[{"type": "int16[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]int16{1, 2},
+	},
+	{
+		def:  `[{"type": "int32[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []int32{1, 2},
+	},
+	{
+		def:  `[{"type": "int32[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]int32{1, 2},
+	},
+	{
+		def:  `[{"type": "int64[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []int64{1, 2},
+	},
+	{
+		def:  `[{"type": "int64[2]"}]`,
+		enc:  "00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: [2]int64{1, 2},
+	},
+	{
+		def:  `[{"type": "int256[]"}]`,
+		enc:  "0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002",
+		want: []*big.Int{big.NewInt(1), big.NewInt(2)},
+	},
+	{
+		def:  `[{"type": "int256[3]"}]`,
+		enc:  "000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000003",
+		want: [3]*big.Int{big.NewInt(1), big.NewInt(2), big.NewInt(3)},
+	},
+}
+
+func TestUnpack(t *testing.T) {
+	for i, test := range unpackTests {
+		def := fmt.Sprintf(`[{ "name" : "method", "outputs": %s}]`, test.def)
+		abi, err := JSON(strings.NewReader(def))
+		if err != nil {
+			t.Fatalf("invalid ABI definition %s: %v", def, err)
 		}
-		if err == nil && len(test.err) != 0 {
-			t.Errorf("%d failed. Expected err: %v but got none", i, test.err)
-			continue
+		encb, err := hex.DecodeString(test.enc)
+		if err != nil {
+			t.Fatalf("invalid hex: %s" + test.enc)
 		}
-		if err != nil && len(test.err) != 0 && err.Error() != test.err {
-			t.Errorf("%d failed. Expected err: '%v' got err: '%v'", i, test.err, err)
+		outptr := reflect.New(reflect.TypeOf(test.want))
+		err = abi.Unpack(outptr.Interface(), "method", encb)
+		if err := test.checkError(err); err != nil {
+			t.Errorf("test %d (%v) failed: %v", i, test.def, err)
 			continue
 		}
-
-		if err == nil {
-			if !reflect.DeepEqual(test.expectedOut, outvar) {
-				t.Errorf("%d failed. Output error: expected %v, got %v", i, test.expectedOut, outvar)
-			}
+		out := outptr.Elem().Interface()
+		if !reflect.DeepEqual(test.want, out) {
+			t.Errorf("test %d (%v) failed: expected %v, got %v", i, test.def, test.want, out)
 		}
 	}
 }
 
-func TestUnpackSetInterfaceSlice(t *testing.T) {
-	var (
-		var1 = new(uint8)
-		var2 = new(uint8)
-	)
-	out := []interface{}{var1, var2}
-	abi, err := JSON(strings.NewReader(`[{"type":"function", "name":"ints", "outputs":[{"type":"uint8"}, {"type":"uint8"}]}]`))
-	if err != nil {
-		t.Fatal(err)
-	}
-	marshalledReturn := append(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"), common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000002")...)
-	err = abi.Unpack(&out, "ints", marshalledReturn)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if *var1 != 1 {
-		t.Error("expected var1 to be 1, got", *var1)
-	}
-	if *var2 != 2 {
-		t.Error("expected var2 to be 2, got", *var2)
-	}
-
-	out = []interface{}{var1}
-	err = abi.Unpack(&out, "ints", marshalledReturn)
-
-	expErr := "abi: cannot marshal in to slices of unequal size (require: 2, got: 1)"
-	if err == nil || err.Error() != expErr {
-		t.Error("expected err:", expErr, "Got:", err)
-	}
-}
-
-func TestUnpackSetInterfaceArrayOutput(t *testing.T) {
-	var (
-		var1 = new([1]uint32)
-		var2 = new([1]uint32)
-	)
-	out := []interface{}{var1, var2}
-	abi, err := JSON(strings.NewReader(`[{"type":"function", "name":"ints", "outputs":[{"type":"uint32[1]"}, {"type":"uint32[1]"}]}]`))
-	if err != nil {
-		t.Fatal(err)
-	}
-	marshalledReturn := append(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"), common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000002")...)
-	err = abi.Unpack(&out, "ints", marshalledReturn)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if *var1 != [1]uint32{1} {
-		t.Error("expected var1 to be [1], got", *var1)
-	}
-	if *var2 != [1]uint32{2} {
-		t.Error("expected var2 to be [2], got", *var2)
-	}
-}
-
 func TestMultiReturnWithStruct(t *testing.T) {
 	const definition = `[
 	{ "name" : "multi", "constant" : false, "outputs": [ { "name": "Int", "type": "uint256" }, { "name": "String", "type": "string" } ] }]`
@@ -337,101 +336,6 @@ func TestMultiReturnWithStruct(t *testing.T) {
 	}
 }
 
-func TestMultiReturnWithSlice(t *testing.T) {
-	const definition = `[
-	{ "name" : "multi", "constant" : false, "outputs": [ { "name": "Int", "type": "uint256" }, { "name": "String", "type": "string" } ] }]`
-
-	abi, err := JSON(strings.NewReader(definition))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// using buff to make the code readable
-	buff := new(bytes.Buffer)
-	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"))
-	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000040"))
-	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000005"))
-	stringOut := "hello"
-	buff.Write(common.RightPadBytes([]byte(stringOut), 32))
-
-	var inter []interface{}
-	err = abi.Unpack(&inter, "multi", buff.Bytes())
-	if err != nil {
-		t.Error(err)
-	}
-
-	if len(inter) != 2 {
-		t.Fatal("expected 2 results got", len(inter))
-	}
-
-	if num, ok := inter[0].(*big.Int); !ok || num.Cmp(big.NewInt(1)) != 0 {
-		t.Error("expected index 0 to be 1 got", num)
-	}
-
-	if str, ok := inter[1].(string); !ok || str != stringOut {
-		t.Error("expected index 1 to be", stringOut, "got", str)
-	}
-}
-
-func TestMarshalArrays(t *testing.T) {
-	const definition = `[
-	{ "name" : "bytes32", "constant" : false, "outputs": [ { "type": "bytes32" } ] },
-	{ "name" : "bytes10", "constant" : false, "outputs": [ { "type": "bytes10" } ] }
-	]`
-
-	abi, err := JSON(strings.NewReader(definition))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	output := common.LeftPadBytes([]byte{1}, 32)
-
-	var bytes10 [10]byte
-	err = abi.Unpack(&bytes10, "bytes32", output)
-	if err == nil || err.Error() != "abi: cannot unmarshal src (len=32) in to dst (len=10)" {
-		t.Error("expected error or bytes32 not be assignable to bytes10:", err)
-	}
-
-	var bytes32 [32]byte
-	err = abi.Unpack(&bytes32, "bytes32", output)
-	if err != nil {
-		t.Error("didn't expect error:", err)
-	}
-	if !bytes.Equal(bytes32[:], output) {
-		t.Error("expected bytes32[31] to be 1 got", bytes32[31])
-	}
-
-	type (
-		B10 [10]byte
-		B32 [32]byte
-	)
-
-	var b10 B10
-	err = abi.Unpack(&b10, "bytes32", output)
-	if err == nil || err.Error() != "abi: cannot unmarshal src (len=32) in to dst (len=10)" {
-		t.Error("expected error or bytes32 not be assignable to bytes10:", err)
-	}
-
-	var b32 B32
-	err = abi.Unpack(&b32, "bytes32", output)
-	if err != nil {
-		t.Error("didn't expect error:", err)
-	}
-	if !bytes.Equal(b32[:], output) {
-		t.Error("expected bytes32[31] to be 1 got", bytes32[31])
-	}
-
-	output[10] = 1
-	var shortAssignLong [32]byte
-	err = abi.Unpack(&shortAssignLong, "bytes10", output)
-	if err != nil {
-		t.Error("didn't expect error:", err)
-	}
-	if !bytes.Equal(output, shortAssignLong[:]) {
-		t.Errorf("expected %x to be %x", shortAssignLong, output)
-	}
-}
-
 func TestUnmarshal(t *testing.T) {
 	const definition = `[
 	{ "name" : "int", "constant" : false, "outputs": [ { "type": "uint256" } ] },
@@ -450,6 +354,29 @@ func TestUnmarshal(t *testing.T) {
 	}
 	buff := new(bytes.Buffer)
 
+	// marshall mixed bytes (mixedBytes)
+	p0, p0Exp := []byte{}, common.Hex2Bytes("01020000000000000000")
+	p1, p1Exp := [32]byte{}, common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000ddeeff")
+	mixedBytes := []interface{}{&p0, &p1}
+
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000040"))
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000ddeeff"))
+	buff.Write(common.Hex2Bytes("000000000000000000000000000000000000000000000000000000000000000a"))
+	buff.Write(common.Hex2Bytes("0102000000000000000000000000000000000000000000000000000000000000"))
+
+	err = abi.Unpack(&mixedBytes, "mixedBytes", buff.Bytes())
+	if err != nil {
+		t.Error(err)
+	} else {
+		if !bytes.Equal(p0, p0Exp) {
+			t.Errorf("unexpected value unpacked: want %x, got %x", p0Exp, p0)
+		}
+
+		if !bytes.Equal(p1[:], p1Exp) {
+			t.Errorf("unexpected value unpacked: want %x, got %x", p1Exp, p1)
+		}
+	}
+
 	// marshal int
 	var Int *big.Int
 	err = abi.Unpack(&Int, "int", common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"))
@@ -473,6 +400,7 @@ func TestUnmarshal(t *testing.T) {
 	}
 
 	// marshal dynamic bytes max length 32
+	buff.Reset()
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020"))
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020"))
 	bytesOut := common.RightPadBytes([]byte("hello"), 32)
@@ -504,11 +432,11 @@ func TestUnmarshal(t *testing.T) {
 		t.Errorf("expected %x got %x", bytesOut, Bytes)
 	}
 
-	// marshall dynamic bytes max length 63
+	// marshall dynamic bytes max length 64
 	buff.Reset()
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020"))
 	buff.Write(common.Hex2Bytes("000000000000000000000000000000000000000000000000000000000000003f"))
-	bytesOut = common.RightPadBytes([]byte("hello"), 63)
+	bytesOut = common.RightPadBytes([]byte("hello"), 64)
 	buff.Write(bytesOut)
 
 	err = abi.Unpack(&Bytes, "bytes", buff.Bytes())
@@ -516,8 +444,8 @@ func TestUnmarshal(t *testing.T) {
 		t.Error(err)
 	}
 
-	if !bytes.Equal(Bytes, bytesOut) {
-		t.Errorf("expected %x got %x", bytesOut, Bytes)
+	if !bytes.Equal(Bytes, bytesOut[:len(bytesOut)-1]) {
+		t.Errorf("expected %x got %x", bytesOut[:len(bytesOut)-1], Bytes)
 	}
 
 	// marshal dynamic bytes output empty
@@ -569,29 +497,6 @@ func TestUnmarshal(t *testing.T) {
 		t.Error("expected error")
 	}
 
-	// marshal mixed bytes
-	buff.Reset()
-	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000040"))
-	fixed := common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001")
-	buff.Write(fixed)
-	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020"))
-	bytesOut = common.RightPadBytes([]byte("hello"), 32)
-	buff.Write(bytesOut)
-
-	var out []interface{}
-	err = abi.Unpack(&out, "mixedBytes", buff.Bytes())
-	if err != nil {
-		t.Fatal("didn't expect error:", err)
-	}
-
-	if !bytes.Equal(bytesOut, out[0].([]byte)) {
-		t.Errorf("expected %x, got %x", bytesOut, out[0])
-	}
-
-	if !bytes.Equal(fixed, out[1].([]byte)) {
-		t.Errorf("expected %x, got %x", fixed, out[1])
-	}
-
 	buff.Reset()
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001"))
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000002"))
diff --git a/accounts/keystore/account_cache.go b/accounts/keystore/account_cache.go
index 4b08cc202..71f698ece 100644
--- a/accounts/keystore/account_cache.go
+++ b/accounts/keystore/account_cache.go
@@ -20,7 +20,6 @@ import (
 	"bufio"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -75,13 +74,6 @@ type accountCache struct {
 	fileC    fileCache
 }
 
-// fileCache is a cache of files seen during scan of keystore
-type fileCache struct {
-	all   *set.SetNonTS // list of all files
-	mtime time.Time     // latest mtime seen
-	mu    sync.RWMutex
-}
-
 func newAccountCache(keydir string) (*accountCache, chan struct{}) {
 	ac := &accountCache{
 		keydir: keydir,
@@ -236,66 +228,22 @@ func (ac *accountCache) close() {
 	ac.mu.Unlock()
 }
 
-// scanFiles performs a new scan on the given directory, compares against the already
-// cached filenames, and returns file sets: new, missing , modified
-func (fc *fileCache) scanFiles(keyDir string) (set.Interface, set.Interface, set.Interface, error) {
-	t0 := time.Now()
-	files, err := ioutil.ReadDir(keyDir)
-	t1 := time.Now()
-	if err != nil {
-		return nil, nil, nil, err
-	}
-	fc.mu.RLock()
-	prevMtime := fc.mtime
-	fc.mu.RUnlock()
-
-	filesNow := set.NewNonTS()
-	moddedFiles := set.NewNonTS()
-	var newMtime time.Time
-	for _, fi := range files {
-		modTime := fi.ModTime()
-		path := filepath.Join(keyDir, fi.Name())
-		if skipKeyFile(fi) {
-			log.Trace("Ignoring file on account scan", "path", path)
-			continue
-		}
-		filesNow.Add(path)
-		if modTime.After(prevMtime) {
-			moddedFiles.Add(path)
-		}
-		if modTime.After(newMtime) {
-			newMtime = modTime
-		}
-	}
-	t2 := time.Now()
-
-	fc.mu.Lock()
-	// Missing = previous - current
-	missing := set.Difference(fc.all, filesNow)
-	// New = current - previous
-	newFiles := set.Difference(filesNow, fc.all)
-	// Modified = modified - new
-	modified := set.Difference(moddedFiles, newFiles)
-	fc.all = filesNow
-	fc.mtime = newMtime
-	fc.mu.Unlock()
-	t3 := time.Now()
-	log.Debug("FS scan times", "list", t1.Sub(t0), "set", t2.Sub(t1), "diff", t3.Sub(t2))
-	return newFiles, missing, modified, nil
-}
-
 // scanAccounts checks if any changes have occurred on the filesystem, and
 // updates the account cache accordingly
 func (ac *accountCache) scanAccounts() error {
-	newFiles, missingFiles, modified, err := ac.fileC.scanFiles(ac.keydir)
-	t1 := time.Now()
+	// Scan the entire folder metadata for file changes
+	creates, deletes, updates, err := ac.fileC.scan(ac.keydir)
 	if err != nil {
 		log.Debug("Failed to reload keystore contents", "err", err)
 		return err
 	}
+	if creates.Size() == 0 && deletes.Size() == 0 && updates.Size() == 0 {
+		return nil
+	}
+	// Create a helper method to scan the contents of the key files
 	var (
-		buf     = new(bufio.Reader)
-		keyJSON struct {
+		buf = new(bufio.Reader)
+		key struct {
 			Address string `json:"address"`
 		}
 	)
@@ -308,9 +256,9 @@ func (ac *accountCache) scanAccounts() error {
 		defer fd.Close()
 		buf.Reset(fd)
 		// Parse the address.
-		keyJSON.Address = ""
-		err = json.NewDecoder(buf).Decode(&keyJSON)
-		addr := common.HexToAddress(keyJSON.Address)
+		key.Address = ""
+		err = json.NewDecoder(buf).Decode(&key)
+		addr := common.HexToAddress(key.Address)
 		switch {
 		case err != nil:
 			log.Debug("Failed to decode keystore key", "path", path, "err", err)
@@ -321,47 +269,30 @@ func (ac *accountCache) scanAccounts() error {
 		}
 		return nil
 	}
+	// Process all the file diffs
+	start := time.Now()
 
-	for _, p := range newFiles.List() {
-		path, _ := p.(string)
-		a := readAccount(path)
-		if a != nil {
+	for _, p := range creates.List() {
+		if a := readAccount(p.(string)); a != nil {
 			ac.add(*a)
 		}
 	}
-	for _, p := range missingFiles.List() {
-		path, _ := p.(string)
-		ac.deleteByFile(path)
+	for _, p := range deletes.List() {
+		ac.deleteByFile(p.(string))
 	}
-
-	for _, p := range modified.List() {
-		path, _ := p.(string)
-		a := readAccount(path)
+	for _, p := range updates.List() {
+		path := p.(string)
 		ac.deleteByFile(path)
-		if a != nil {
+		if a := readAccount(path); a != nil {
 			ac.add(*a)
 		}
 	}
-
-	t2 := time.Now()
+	end := time.Now()
 
 	select {
 	case ac.notify <- struct{}{}:
 	default:
 	}
-	log.Trace("Handled keystore changes", "time", t2.Sub(t1))
-
+	log.Trace("Handled keystore changes", "time", end.Sub(start))
 	return nil
 }
-
-func skipKeyFile(fi os.FileInfo) bool {
-	// Skip editor backups and UNIX-style hidden files.
-	if strings.HasSuffix(fi.Name(), "~") || strings.HasPrefix(fi.Name(), ".") {
-		return true
-	}
-	// Skip misc special files, directories (yes, symlinks too).
-	if fi.IsDir() || fi.Mode()&os.ModeType != 0 {
-		return true
-	}
-	return false
-}
diff --git a/accounts/keystore/account_cache_test.go b/accounts/keystore/account_cache_test.go
index e3dc31065..fe9233c04 100644
--- a/accounts/keystore/account_cache_test.go
+++ b/accounts/keystore/account_cache_test.go
@@ -59,7 +59,7 @@ func TestWatchNewFile(t *testing.T) {
 
 	// Ensure the watcher is started before adding any files.
 	ks.Accounts()
-	time.Sleep(200 * time.Millisecond)
+	time.Sleep(1000 * time.Millisecond)
 
 	// Move in the files.
 	wantAccounts := make([]accounts.Account, len(cachetestAccounts))
@@ -349,6 +349,9 @@ func TestUpdatedKeyfileContents(t *testing.T) {
 		return
 	}
 
+	// needed so that modTime of `file` is different to its current value after forceCopyFile
+	time.Sleep(1000 * time.Millisecond)
+
 	// Now replace file contents
 	if err := forceCopyFile(file, cachetestAccounts[1].URL.Path); err != nil {
 		t.Fatal(err)
@@ -362,6 +365,9 @@ func TestUpdatedKeyfileContents(t *testing.T) {
 		return
 	}
 
+	// needed so that modTime of `file` is different to its current value after forceCopyFile
+	time.Sleep(1000 * time.Millisecond)
+
 	// Now replace file contents again
 	if err := forceCopyFile(file, cachetestAccounts[2].URL.Path); err != nil {
 		t.Fatal(err)
@@ -374,6 +380,10 @@ func TestUpdatedKeyfileContents(t *testing.T) {
 		t.Error(err)
 		return
 	}
+
+	// needed so that modTime of `file` is different to its current value after ioutil.WriteFile
+	time.Sleep(1000 * time.Millisecond)
+
 	// Now replace file contents with crap
 	if err := ioutil.WriteFile(file, []byte("foo"), 0644); err != nil {
 		t.Fatal(err)
diff --git a/accounts/keystore/file_cache.go b/accounts/keystore/file_cache.go
new file mode 100644
index 000000000..c91b7b7b6
--- /dev/null
+++ b/accounts/keystore/file_cache.go
@@ -0,0 +1,102 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package keystore
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	set "gopkg.in/fatih/set.v0"
+)
+
+// fileCache is a cache of files seen during scan of keystore.
+type fileCache struct {
+	all     *set.SetNonTS // Set of all files from the keystore folder
+	lastMod time.Time     // Last time instance when a file was modified
+	mu      sync.RWMutex
+}
+
+// scan performs a new scan on the given directory, compares against the already
+// cached filenames, and returns file sets: creates, deletes, updates.
+func (fc *fileCache) scan(keyDir string) (set.Interface, set.Interface, set.Interface, error) {
+	t0 := time.Now()
+
+	// List all the failes from the keystore folder
+	files, err := ioutil.ReadDir(keyDir)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	t1 := time.Now()
+
+	fc.mu.Lock()
+	defer fc.mu.Unlock()
+
+	// Iterate all the files and gather their metadata
+	all := set.NewNonTS()
+	mods := set.NewNonTS()
+
+	var newLastMod time.Time
+	for _, fi := range files {
+		// Skip any non-key files from the folder
+		path := filepath.Join(keyDir, fi.Name())
+		if skipKeyFile(fi) {
+			log.Trace("Ignoring file on account scan", "path", path)
+			continue
+		}
+		// Gather the set of all and fresly modified files
+		all.Add(path)
+
+		modified := fi.ModTime()
+		if modified.After(fc.lastMod) {
+			mods.Add(path)
+		}
+		if modified.After(newLastMod) {
+			newLastMod = modified
+		}
+	}
+	t2 := time.Now()
+
+	// Update the tracked files and return the three sets
+	deletes := set.Difference(fc.all, all)   // Deletes = previous - current
+	creates := set.Difference(all, fc.all)   // Creates = current - previous
+	updates := set.Difference(mods, creates) // Updates = modified - creates
+
+	fc.all, fc.lastMod = all, newLastMod
+	t3 := time.Now()
+
+	// Report on the scanning stats and return
+	log.Debug("FS scan times", "list", t1.Sub(t0), "set", t2.Sub(t1), "diff", t3.Sub(t2))
+	return creates, deletes, updates, nil
+}
+
+// skipKeyFile ignores editor backups, hidden files and folders/symlinks.
+func skipKeyFile(fi os.FileInfo) bool {
+	// Skip editor backups and UNIX-style hidden files.
+	if strings.HasSuffix(fi.Name(), "~") || strings.HasPrefix(fi.Name(), ".") {
+		return true
+	}
+	// Skip misc special files, directories (yes, symlinks too).
+	if fi.IsDir() || fi.Mode()&os.ModeType != 0 {
+		return true
+	}
+	return false
+}
diff --git a/accounts/keystore/keystore_passphrase.go b/accounts/keystore/keystore_passphrase.go
index 535608a60..eaec39f7d 100644
--- a/accounts/keystore/keystore_passphrase.go
+++ b/accounts/keystore/keystore_passphrase.go
@@ -28,6 +28,7 @@ package keystore
 import (
 	"bytes"
 	"crypto/aes"
+	crand "crypto/rand"
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
@@ -90,6 +91,12 @@ func (ks keyStorePassphrase) GetKey(addr common.Address, filename, auth string)
 	return key, nil
 }
 
+// StoreKey generates a key, encrypts with 'auth' and stores in the given directory
+func StoreKey(dir, auth string, scryptN, scryptP int) (common.Address, error) {
+	_, a, err := storeNewKey(&keyStorePassphrase{dir, scryptN, scryptP}, crand.Reader, auth)
+	return a.Address, err
+}
+
 func (ks keyStorePassphrase) StoreKey(filename string, key *Key, auth string) error {
 	keyjson, err := EncryptKey(key, auth, ks.scryptN, ks.scryptP)
 	if err != nil {
diff --git a/accounts/keystore/presale.go b/accounts/keystore/presale.go
index ed900ad08..1554294e1 100644
--- a/accounts/keystore/presale.go
+++ b/accounts/keystore/presale.go
@@ -58,6 +58,9 @@ func decryptPreSaleKey(fileContent []byte, password string) (key *Key, err error
 	if err != nil {
 		return nil, errors.New("invalid hex in encSeed")
 	}
+	if len(encSeedBytes) < 16 {
+		return nil, errors.New("invalid encSeed, too short")
+	}
 	iv := encSeedBytes[:16]
 	cipherText := encSeedBytes[16:]
 	/*
diff --git a/accounts/keystore/watch.go b/accounts/keystore/watch.go
index 602300b10..bbcfb9925 100644
--- a/accounts/keystore/watch.go
+++ b/accounts/keystore/watch.go
@@ -81,10 +81,14 @@ func (w *watcher) loop() {
 	// When an event occurs, the reload call is delayed a bit so that
 	// multiple events arriving quickly only cause a single reload.
 	var (
-		debounce         = time.NewTimer(0)
 		debounceDuration = 500 * time.Millisecond
 		rescanTriggered  = false
+		debounce         = time.NewTimer(0)
 	)
+	// Ignore initial trigger
+	if !debounce.Stop() {
+		<-debounce.C
+	}
 	defer debounce.Stop()
 	for {
 		select {
diff --git a/accounts/manager.go b/accounts/manager.go
index 78ddb1368..96ca298fc 100644
--- a/accounts/manager.go
+++ b/accounts/manager.go
@@ -41,6 +41,11 @@ type Manager struct {
 // NewManager creates a generic account manager to sign transaction via various
 // supported backends.
 func NewManager(backends ...Backend) *Manager {
+	// Retrieve the initial list of wallets from the backends and sort by URL
+	var wallets []Wallet
+	for _, backend := range backends {
+		wallets = merge(wallets, backend.Wallets()...)
+	}
 	// Subscribe to wallet notifications from all backends
 	updates := make(chan WalletEvent, 4*len(backends))
 
@@ -48,11 +53,6 @@ func NewManager(backends ...Backend) *Manager {
 	for i, backend := range backends {
 		subs[i] = backend.Subscribe(updates)
 	}
-	// Retrieve the initial list of wallets from the backends and sort by URL
-	var wallets []Wallet
-	for _, backend := range backends {
-		wallets = merge(wallets, backend.Wallets()...)
-	}
 	// Assemble the account manager and return
 	am := &Manager{
 		backends: make(map[reflect.Type][]Backend),