Add strkey for string encoding

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
+}

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
+}

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...'
+)