path: root/accounts/keystore/key.go

// Copyright 2014 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 (
    "bytes"
    "crypto/ecdsa"
    "encoding/hex"
    "encoding/json"
    "fmt"
    "io"
    "io/ioutil"
    "os"
    "path/filepath"
    "strings"
    "time"

    "github.com/ethereum/go-ethereum/accounts"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/pborman/uuid"
)

const (
    version = 3
)

type Key struct {
    Id uuid.UUID // Version 4 "random" for unique id not derived from key data
    // to simplify lookups we also store the address
    Address common.Address
    // we only store privkey as pubkey/address can be derived from it
    // privkey in this struct is always in plaintext
    PrivateKey *ecdsa.PrivateKey
}

type keyStore interface {
    // Loads and decrypts the key from disk.
    GetKey(addr common.Address, filename string, auth string) (*Key, error)
    // Writes and encrypts the key.
    StoreKey(filename string, k *Key, auth string) error
    // Joins filename with the key directory unless it is already absolute.
    JoinPath(filename string) string
}

type plainKeyJSON struct {
    Address    string `json:"address"`
    PrivateKey string `json:"privatekey"`
    Id         string `json:"id"`
    Version    int    `json:"version"`
}

type encryptedKeyJSONV3 struct {
    Address string     `json:"address"`
    Crypto  cryptoJSON `json:"crypto"`
    Id      string     `json:"id"`
    Version int        `json:"version"`
}

type encryptedKeyJSONV1 struct {
    Address string     `json:"address"`
    Crypto  cryptoJSON `json:"crypto"`
    Id      string     `json:"id"`
    Version string     `json:"version"`
}

type cryptoJSON struct {
    Cipher       string                 `json:"cipher"`
    CipherText   string                 `json:"ciphertext"`
    CipherParams cipherparamsJSON       `json:"cipherparams"`
    KDF          string                 `json:"kdf"`
    KDFParams    map[string]interface{} `json:"kdfparams"`
    MAC          string                 `json:"mac"`
}

type cipherparamsJSON struct {
    IV string `json:"iv"`
}

type scryptParamsJSON struct {
    N     int    `json:"n"`
    R     int    `json:"r"`
    P     int    `json:"p"`
    DkLen int    `json:"dklen"`
    Salt  string `json:"salt"`
}

func (k *Key) MarshalJSON() (j []byte, err error) {
    jStruct := plainKeyJSON{
        hex.EncodeToString(k.Address[:]),
        hex.EncodeToString(crypto.FromECDSA(k.PrivateKey)),
        k.Id.String(),
        version,
    }
    j, err = json.Marshal(jStruct)
    return j, err
}

func (k *Key) UnmarshalJSON(j []byte) (err error) {
    keyJSON := new(plainKeyJSON)
    err = json.Unmarshal(j, &keyJSON)
    if err != nil {
        return err
    }

    u := new(uuid.UUID)
    *u = uuid.Parse(keyJSON.Id)
    k.Id = *u
    addr, err := hex.DecodeString(keyJSON.Address)
    if err != nil {
        return err
    }
    privkey, err := crypto.HexToECDSA(keyJSON.PrivateKey)
    if err != nil {
        return err
    }

    k.Address = common.BytesToAddress(addr)
    k.PrivateKey = privkey

    return nil
}

func newKeyFromECDSA(privateKeyECDSA *ecdsa.PrivateKey) *Key {
    id := uuid.NewRandom()
    key := &Key{
        Id:         id,
        Address:    crypto.PubkeyToAddress(privateKeyECDSA.PublicKey),
        PrivateKey: privateKeyECDSA,
    }
    return key
}

// NewKeyForDirectICAP generates a key whose address fits into < 155 bits so it can fit
// into the Direct ICAP spec. for simplicity and easier compatibility with other libs, we
// retry until the first byte is 0.
func NewKeyForDirectICAP(rand io.Reader) *Key {
    randBytes := make([]byte, 64)
    _, err := rand.Read(randBytes)
    if err != nil {
        panic("key generation: could not read from random source: " + err.Error())
    }
    reader := bytes.NewReader(randBytes)
    privateKeyECDSA, err := ecdsa.GenerateKey(crypto.S256(), reader)
    if err != nil {
        panic("key generation: ecdsa.GenerateKey failed: " + err.Error())
    }
    key := newKeyFromECDSA(privateKeyECDSA)
    if !strings.HasPrefix(key.Address.Hex(), "0x00") {
        return NewKeyForDirectICAP(rand)
    }
    return key
}

func newKey(rand io.Reader) (*Key, error) {
    privateKeyECDSA, err := ecdsa.GenerateKey(crypto.S256(), rand)
    if err != nil {
        return nil, err
    }
    return newKeyFromECDSA(privateKeyECDSA), nil
}

func storeNewKey(ks keyStore, rand io.Reader, auth string) (*Key, accounts.Account, error) {
    key, err := newKey(rand)
    if err != nil {
        return nil, accounts.Account{}, err
    }
    a := accounts.Account{Address: key.Address, URL: accounts.URL{Scheme: KeyStoreScheme, Path: ks.JoinPath(keyFileName(key.Address))}}
    if err := ks.StoreKey(a.URL.Path, key, auth); err != nil {
        zeroKey(key.PrivateKey)
        return nil, a, err
    }
    return key, a, err
}

func writeKeyFile(file string, content []byte) error {
    // Create the keystore directory with appropriate permissions
    // in case it is not present yet.
    const dirPerm = 0700
    if err := os.MkdirAll(filepath.Dir(file), dirPerm); err != nil {
        return err
    }
    // Atomic write: create a temporary hidden file first
    // then move it into place. TempFile assigns mode 0600.
    f, err := ioutil.TempFile(filepath.Dir(file), "."+filepath.Base(file)+".tmp")
    if err != nil {
        return err
    }
    if _, err := f.Write(content); err != nil {
        f.Close()
        os.Remove(f.Name())
        return err
    }
    f.Close()
    return os.Rename(f.Name(), file)
}

// keyFileName implements the naming convention for keyfiles:
// UTC--<created_at UTC ISO8601>-<address hex>
func keyFileName(keyAddr common.Address) string {
    ts := time.Now().UTC()
    return fmt.Sprintf("UTC--%s--%s", toISO8601(ts), hex.EncodeToString(keyAddr[:]))
}

func toISO8601(t time.Time) string {
    var tz string
    name, offset := t.Zone()
    if name == "UTC" {
        tz = "Z"
    } else {
        tz = fmt.Sprintf("%03d00", offset/3600)
    }
    return fmt.Sprintf("%04d-%02d-%02dT%02d-%02d-%02d.%09d%s", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), tz)
}