cashaddrjs-slp
Version:
SLP & Bitcoin Cash cashaddr address format support for Node.js and web browsers.
332 lines (310 loc) • 8.91 kB
JavaScript
/**
* @license
* https://github.com/bitcoincashjs/cashaddr
* Copyright (c) 2017-2018 Emilio Almansi
* Distributed under the MIT software license, see the accompanying
* file LICENSE or http://www.opensource.org/licenses/mit-license.php.
*/
'use strict';
var base32 = require('./base32');
var bigInt = require('big-integer');
var convertBits = require('./convertBits');
var validation = require('./validation');
var validate = validation.validate;
/**
* Encoding and decoding of the new Cash Address format for Bitcoin Cash. <br />
* Compliant with the original cashaddr specification:
* {@link https://github.com/Bitcoin-UAHF/spec/blob/master/cashaddr.md}
* @module cashaddr
*/
/**
* Encodes a hash from a given type into a Bitcoin Cash address with the given prefix.
*
* @static
* @param {string} prefix Network prefix. E.g.: 'bitcoincash'.
* @param {string} type Type of address to generate. Either 'P2PKH' or 'P2SH'.
* @param {Uint8Array} hash Hash to encode represented as an array of 8-bit integers.
* @returns {string}
* @throws {ValidationError}
*/
function encode(prefix, type, hash) {
validate(typeof prefix === 'string' && isValidPrefix(prefix), 'Invalid prefix: ' + prefix + '.');
validate(typeof type === 'string', 'Invalid type: ' + type + '.');
validate(hash instanceof Uint8Array, 'Invalid hash: ' + hash + '.');
var prefixData = concat(prefixToUint5Array(prefix), new Uint8Array(1));
var versionByte = getTypeBits(type) + getHashSizeBits(hash);
var payloadData = toUint5Array(concat(Uint8Array.of(versionByte), hash));
var checksumData = concat(concat(prefixData, payloadData), new Uint8Array(8));
var payload = concat(payloadData, checksumToUint5Array(polymod(checksumData)));
return prefix + ':' + base32.encode(payload);
}
/**
* Decodes the given address into its constituting prefix, type and hash. See [#encode()]{@link encode}.
*
* @static
* @param {string} address Address to decode. E.g.: 'bitcoincash:qpm2qsznhks23z7629mms6s4cwef74vcwvy22gdx6a'.
* @returns {object}
* @throws {ValidationError}
*/
function decode(address) {
validate(typeof address === 'string' && hasSingleCase(address), 'Invalid address: ' + address + '.');
var pieces = address.toLowerCase().split(':');
validate(pieces.length === 2, 'Missing prefix: ' + address + '.');
var prefix = pieces[0];
var payload = base32.decode(pieces[1]);
validate(validChecksum(prefix, payload), 'Invalid checksum: ' + address + '.');
var payloadData = fromUint5Array(payload.slice(0, -8));
var versionByte = payloadData[0];
var hash = payloadData.slice(1);
validate(getHashSize(versionByte) === hash.length * 8, 'Invalid hash size: ' + address + '.');
var type = getType(versionByte);
return {
prefix: prefix,
type: type,
hash: hash,
};
}
/**
* Error thrown when encoding or decoding fail due to invalid input.
*
* @constructor ValidationError
* @param {string} message Error description.
*/
var ValidationError = validation.ValidationError;
/**
* Valid address prefixes.
*
* @private
*/
var VALID_PREFIXES = ['bitcoincash', 'bchtest', 'bchreg', 'simpleledger', 'slptest', 'slpreg'];
/**
* Checks whether a string is a valid prefix; ie., it has a single letter case
* and is one of 'bitcoincash', 'bchtest', or 'bchreg'.
*
* @private
* @param {string} prefix
* @returns {boolean}
*/
function isValidPrefix(prefix) {
return hasSingleCase(prefix) && VALID_PREFIXES.indexOf(prefix.toLowerCase()) !== -1;
}
/**
* Derives an array from the given prefix to be used in the computation
* of the address' checksum.
*
* @private
* @param {string} prefix Network prefix. E.g.: 'bitcoincash'.
* @returns {Uint8Array}
*/
function prefixToUint5Array(prefix) {
var result = new Uint8Array(prefix.length);
for (var i = 0; i < prefix.length; ++i) {
result[i] = prefix[i].charCodeAt(0) & 31;
}
return result;
}
/**
* Returns an array representation of the given checksum to be encoded
* within the address' payload.
*
* @private
* @param {BigInteger} checksum Computed checksum.
* @returns {Uint8Array}
*/
function checksumToUint5Array(checksum) {
var result = new Uint8Array(8);
for (var i = 0; i < 8; ++i) {
result[7 - i] = checksum.and(31).toJSNumber();
checksum = checksum.shiftRight(5);
}
return result;
}
/**
* Returns the bit representation of the given type within the version
* byte.
*
* @private
* @param {string} type Address type. Either 'P2PKH' or 'P2SH'.
* @returns {number}
* @throws {ValidationError}
*/
function getTypeBits(type) {
switch (type) {
case 'P2PKH':
return 0;
case 'P2SH':
return 8;
default:
throw new ValidationError('Invalid type: ' + type + '.');
}
}
/**
* Retrieves the address type from its bit representation within the
* version byte.
*
* @private
* @param {number} versionByte
* @returns {string}
* @throws {ValidationError}
*/
function getType(versionByte) {
switch (versionByte & 120) {
case 0:
return 'P2PKH';
case 8:
return 'P2SH';
default:
throw new ValidationError('Invalid address type in version byte: ' + versionByte + '.');
}
}
/**
* Returns the bit representation of the length in bits of the given
* hash within the version byte.
*
* @private
* @param {Uint8Array} hash Hash to encode represented as an array of 8-bit integers.
* @returns {number}
* @throws {ValidationError}
*/
function getHashSizeBits(hash) {
switch (hash.length * 8) {
case 160:
return 0;
case 192:
return 1;
case 224:
return 2;
case 256:
return 3;
case 320:
return 4;
case 384:
return 5;
case 448:
return 6;
case 512:
return 7;
default:
throw new ValidationError('Invalid hash size: ' + hash.length + '.');
}
}
/**
* Retrieves the the length in bits of the encoded hash from its bit
* representation within the version byte.
*
* @private
* @param {number} versionByte
* @returns {number}
*/
function getHashSize(versionByte) {
switch (versionByte & 7) {
case 0:
return 160;
case 1:
return 192;
case 2:
return 224;
case 3:
return 256;
case 4:
return 320;
case 5:
return 384;
case 6:
return 448;
case 7:
return 512;
}
}
/**
* Converts an array of 8-bit integers into an array of 5-bit integers,
* right-padding with zeroes if necessary.
*
* @private
* @param {Uint8Array} data
* @returns {Uint8Array}
*/
function toUint5Array(data) {
return convertBits(data, 8, 5);
}
/**
* Converts an array of 5-bit integers back into an array of 8-bit integers,
* removing extra zeroes left from padding if necessary.
* Throws a {@link ValidationError} if input is not a zero-padded array of 8-bit integers.
*
* @private
* @param {Uint8Array} data
* @returns {Uint8Array}
* @throws {ValidationError}
*/
function fromUint5Array(data) {
return convertBits(data, 5, 8, true);
}
/**
* Returns the concatenation a and b.
*
* @private
* @param {Uint8Array} a
* @param {Uint8Array} b
* @returns {Uint8Array}
* @throws {ValidationError}
*/
function concat(a, b) {
var ab = new Uint8Array(a.length + b.length);
ab.set(a);
ab.set(b, a.length);
return ab;
}
/**
* Computes a checksum from the given input data as specified for the CashAddr
* format: https://github.com/Bitcoin-UAHF/spec/blob/master/cashaddr.md.
*
* @private
* @param {Uint8Array} data Array of 5-bit integers over which the checksum is to be computed.
* @returns {BigInteger}
*/
function polymod(data) {
var GENERATOR = [0x98f2bc8e61, 0x79b76d99e2, 0xf33e5fb3c4, 0xae2eabe2a8, 0x1e4f43e470];
var checksum = bigInt(1);
for (var i = 0; i < data.length; ++i) {
var value = data[i];
var topBits = checksum.shiftRight(35);
checksum = checksum.and(0x07ffffffff).shiftLeft(5).xor(value);
for (var j = 0; j < GENERATOR.length; ++j) {
if (topBits.shiftRight(j).and(1).equals(1)) {
checksum = checksum.xor(GENERATOR[j]);
}
}
}
return checksum.xor(1);
}
/**
* Verify that the payload has not been corrupted by checking that the
* checksum is valid.
*
* @private
* @param {string} prefix Network prefix. E.g.: 'bitcoincash'.
* @param {Uint8Array} payload Array of 5-bit integers containing the address' payload.
* @returns {boolean}
*/
function validChecksum(prefix, payload) {
var prefixData = concat(prefixToUint5Array(prefix), new Uint8Array(1));
var checksumData = concat(prefixData, payload);
return polymod(checksumData).equals(0);
}
/**
* Returns true if, and only if, the given string contains either uppercase
* or lowercase letters, but not both.
*
* @private
* @param {string} string Input string.
* @returns {boolean}
*/
function hasSingleCase(string) {
return string === string.toLowerCase() || string === string.toUpperCase();
}
module.exports = {
encode: encode,
decode: decode,
ValidationError: ValidationError,
};