diff --git a/util/crc16/crc16.go b/util/crc16/crc16.go new file mode 100644 index 00000000..810f4bed --- /dev/null +++ b/util/crc16/crc16.go @@ -0,0 +1,122 @@ +// Package crc16 is implementation according to CCITT standards. +// +// Note by @antirez: this is actually the XMODEM CRC 16 algorithm, using the +// following parameters: +// +// Name : "XMODEM", also known as "ZMODEM", "CRC-16/ACORN" +// Width : 16 bit +// Poly : 1021 (That is actually x^16 + x^12 + x^5 + 1) +// Initialization : 0000 +// Reflect Input byte : False +// Reflect Output CRC : False +// Xor constant to output CRC : 0000 +// Output for "123456789" : 31C3 +// +// ported from the c++ code in the stellar-core codebase +// (https://github.com/stellar/stellar-core). The code is licensed +// as: +/* + * Copyright 2001-2010 Georges Menie (www.menie.org) + * Copyright 2010-2012 Salvatore Sanfilippo (adapted to Redis coding style) + * Copyright 2015 Stellar Development Foundation (ported to go) + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of the University of California, Berkeley nor the + * names of its contributors may be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +package crc16 + +import ( + "bytes" + "encoding/binary" + "fmt" +) + +// ErrInvalidChecksum is returned when Validate determines either the checksum +// or the payload has been corrupted +var ErrInvalidChecksum = fmt.Errorf("invalid checksum") + +var crc16tab = [256]uint16{ + 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, + 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, + 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, + 0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, + 0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, + 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, + 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, + 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, + 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, + 0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, + 0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, + 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, + 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, + 0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, + 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, + 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, + 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, + 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, + 0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, + 0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, + 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, + 0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, + 0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, + 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, + 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, + 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, + 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, + 0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, + 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, + 0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, + 0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, + 0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0, +} + +// Checksum returns the 2-byte checksum for the provided data +func Checksum(data []byte) []byte { + var crc uint16 + var out bytes.Buffer + for _, b := range data { + crc = ((crc << 8) & 0xffff) ^ crc16tab[((crc>>8)^uint16(b))&0x00FF] + } + + err := binary.Write(&out, binary.LittleEndian, crc) + if err != nil { + panic(err) + } + + return out.Bytes() +} + +// Validate returns an error if the provided checksum does not match +// the calculated checksum of the provided data +func Validate(data []byte, expected []byte) error { + + actual := Checksum(data) + + // validate the provided checksum against the calculated + if !bytes.Equal(actual, expected) { + return ErrInvalidChecksum + } + + return nil +} diff --git a/util/strkey/strkey.go b/util/strkey/strkey.go new file mode 100644 index 00000000..c6dcfc3b --- /dev/null +++ b/util/strkey/strkey.go @@ -0,0 +1,117 @@ +package strkey + +import ( + "bytes" + "encoding/binary" + "fmt" + "github.com/anytypeio/any-sync/util/crc16" + + "github.com/mr-tron/base58/base58" +) + +// ErrInvalidVersionByte is returned when the version byte from a provided +// strkey-encoded string is not one of the valid values. +var ErrInvalidVersionByte = fmt.Errorf("invalid version byte") + +// VersionByte represents one of the possible prefix values for a StrKey base +// string--the string the when encoded using base58 yields a final StrKey. +type VersionByte byte + +// Decode decodes the provided StrKey into a raw value, checking the checksum +// and ensuring the expected VersionByte (the version parameter) is the value +// actually encoded into the provided src string. +func Decode(expected VersionByte, src string) ([]byte, error) { + raw, err := decodeString(src) + if err != nil { + return nil, err + } + + // decode into components + version := VersionByte(raw[0]) + vp := raw[0 : len(raw)-2] + payload := raw[1 : len(raw)-2] + checksum := raw[len(raw)-2:] + + // ensure version byte is expected + if version != expected { + return nil, ErrInvalidVersionByte + } + + // ensure checksum is valid + if err := crc16.Validate(vp, checksum); err != nil { + return nil, err + } + + // if we made it through the gaunlet, return the decoded value + return payload, nil +} + +// MustDecode is like Decode, but panics on error +func MustDecode(expected VersionByte, src string) []byte { + d, err := Decode(expected, src) + if err != nil { + panic(err) + } + return d +} + +// Encode encodes the provided data to a StrKey, using the provided version +// byte. +func Encode(version VersionByte, src []byte) (string, error) { + var raw bytes.Buffer + + // write version byte + if err := binary.Write(&raw, binary.LittleEndian, version); err != nil { + return "", err + } + + // write payload + if _, err := raw.Write(src); err != nil { + return "", err + } + + // calculate and write checksum + checksum := crc16.Checksum(raw.Bytes()) + if _, err := raw.Write(checksum); err != nil { + return "", err + } + + result := base58.FastBase58Encoding(raw.Bytes()) + return result, nil +} + +// MustEncode is like Encode, but panics on error +func MustEncode(version VersionByte, src []byte) string { + e, err := Encode(version, src) + if err != nil { + panic(err) + } + return e +} + +// Version extracts and returns the version byte from the provided source +// string. +func Version(src string) (VersionByte, error) { + raw, err := decodeString(src) + if err != nil { + return VersionByte(0), err + } + + return VersionByte(raw[0]), nil +} + +// decodeString decodes a base58 string into the raw bytes, and ensures it could +// potentially be strkey encoded (i.e. it has both a version byte and a +// checksum, neither of which are explicitly checked by this func) +func decodeString(src string) ([]byte, error) { + raw, err := base58.FastBase58Decoding(src) + if err != nil { + return nil, fmt.Errorf("base58 decode failed: %s", err) + } + + if len(raw) < 3 { + return nil, fmt.Errorf("encoded value is %d bytes; minimum valid length is 3", len(raw)) + } + + return raw, nil +} diff --git a/util/strkey/versions.go b/util/strkey/versions.go new file mode 100644 index 00000000..d59becdf --- /dev/null +++ b/util/strkey/versions.go @@ -0,0 +1,7 @@ +package strkey + +const ( + AccountAddressVersionByte VersionByte = 0x5b // Base58-encodes to 'A...' + AccountSeedVersionByte VersionByte = 0xff // Base58-encodes to 'S...' + DeviceSeedVersionByte VersionByte = 0x7d // Base58-encodes to 'D...' +)