From 2db97986460c57ba74a563d97a704a45a270df7d Mon Sep 17 00:00:00 2001 From: Gustav Simonsson Date: Tue, 6 Oct 2015 18:39:42 +0200 Subject: common, crypto: add ICAP functions --- common/icap.go | 190 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 190 insertions(+) create mode 100644 common/icap.go (limited to 'common/icap.go') diff --git a/common/icap.go b/common/icap.go new file mode 100644 index 000000000..a36e669b3 --- /dev/null +++ b/common/icap.go @@ -0,0 +1,190 @@ +// Copyright 2015 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 . + +// Spec at https://github.com/ethereum/wiki/wiki/ICAP:-Inter-exchange-Client-Address-Protocol + +package common + +import ( + "errors" + "math/big" + "strconv" + "strings" +) + +var ( + Base36Chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" + ICAPLengthError = errors.New("Invalid ICAP length") + ICAPEncodingError = errors.New("Invalid ICAP encoding") + ICAPChecksumError = errors.New("Invalid ICAP checksum") + ICAPCountryCodeError = errors.New("Invalid ICAP country code") + ICAPAssetIdentError = errors.New("Invalid ICAP asset identifier") + ICAPInstCodeError = errors.New("Invalid ICAP institution code") + ICAPClientIdentError = errors.New("Invalid ICAP client identifier") +) + +func ICAPToAddress(s string) (Address, error) { + switch len(s) { + case 35: // "XE" + 2 digit checksum + 31 base-36 chars of address + return parseICAP(s) + case 34: // "XE" + 2 digit checksum + 30 base-36 chars of address + return parseICAP(s) + case 20: // "XE" + 2 digit checksum + 3-char asset identifier + + // 4-char institution identifier + 9-char institution client identifier + return parseIndirectICAP(s) + default: + return Address{}, ICAPLengthError + } +} + +func parseICAP(s string) (Address, error) { + if !strings.HasPrefix(s, "XE") { + return Address{}, ICAPCountryCodeError + } + if err := validCheckSum(s); err != nil { + return Address{}, err + } + // checksum is ISO13616, Ethereum address is base-36 + bigAddr, _ := new(big.Int).SetString(s[4:], 36) + return BigToAddress(bigAddr), nil +} + +func parseIndirectICAP(s string) (Address, error) { + if !strings.HasPrefix(s, "XE") { + return Address{}, ICAPCountryCodeError + } + if s[4:7] != "ETH" { + return Address{}, ICAPAssetIdentError + } + if err := validCheckSum(s); err != nil { + return Address{}, err + } + // TODO: integrate with ICAP namereg + return Address{}, errors.New("not implemented") +} + +func AddressToICAP(a Address) (string, error) { + enc := base36Encode(a.Big()) + // zero padd encoded address to Direct ICAP length if needed + if len(enc) < 30 { + enc = join(strings.Repeat("0", 30-len(enc)), enc) + } + icap := join("XE", checkDigits(enc), enc) + return icap, nil +} + +// TODO: integrate with ICAP namereg when it's available +func AddressToIndirectICAP(a Address, instCode string) (string, error) { + // return addressToIndirectICAP(a, instCode) + return "", errors.New("not implemented") +} + +func addressToIndirectICAP(a Address, instCode string) (string, error) { + // TODO: add addressToClientIdent which grabs client ident from ICAP namereg + //clientIdent := addressToClientIdent(a) + clientIdent := "todo" + return clientIdentToIndirectICAP(instCode, clientIdent) +} + +func clientIdentToIndirectICAP(instCode, clientIdent string) (string, error) { + if len(instCode) != 4 || !validBase36(instCode) { + return "", ICAPInstCodeError + } + if len(clientIdent) != 9 || !validBase36(instCode) { + return "", ICAPClientIdentError + } + + // currently ETH is only valid asset identifier + s := join("ETH", instCode, clientIdent) + return join("XE", checkDigits(s), s), nil +} + +// https://en.wikipedia.org/wiki/International_Bank_Account_Number#Validating_the_IBAN +func validCheckSum(s string) error { + s = join(s[4:], s[:4]) + expanded, err := iso13616Expand(s) + if err != nil { + return err + } + checkSumNum, _ := new(big.Int).SetString(expanded, 10) + if checkSumNum.Mod(checkSumNum, Big97).Cmp(Big1) != 0 { + return ICAPChecksumError + } + return nil +} + +func checkDigits(s string) string { + expanded, _ := iso13616Expand(strings.Join([]string{s, "XE00"}, "")) + num, _ := new(big.Int).SetString(expanded, 10) + num.Sub(Big98, num.Mod(num, Big97)) + + checkDigits := num.String() + // zero padd checksum + if len(checkDigits) == 1 { + checkDigits = join("0", checkDigits) + } + return checkDigits +} + +// not base-36, but expansion to decimal literal: A = 10, B = 11, ... Z = 35 +func iso13616Expand(s string) (string, error) { + var parts []string + if !validBase36(s) { + return "", ICAPEncodingError + } + for _, c := range s { + i := uint64(c) + if i >= 65 { + parts = append(parts, strconv.FormatUint(uint64(c)-55, 10)) + } else { + parts = append(parts, string(c)) + } + } + return join(parts...), nil +} + +func base36Encode(i *big.Int) string { + var chars []rune + x := new(big.Int) + for { + x.Mod(i, Big36) + chars = append(chars, rune(Base36Chars[x.Uint64()])) + i.Div(i, Big36) + if i.Cmp(Big0) == 0 { + break + } + } + // reverse slice + for i, j := 0, len(chars)-1; i < j; i, j = i+1, j-1 { + chars[i], chars[j] = chars[j], chars[i] + } + return string(chars) +} + +func validBase36(s string) bool { + for _, c := range s { + i := uint64(c) + // 0-9 or A-Z + if i < 48 || (i > 57 && i < 65) || i > 90 { + return false + } + } + return true +} + +func join(s ...string) string { + return strings.Join(s, "") +} -- cgit