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convert.js
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convert.js
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var Crypto = require('crypto-js');
var WordArray = Crypto.lib.WordArray;
var base64map = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
function lpad(str, padString, length) {
while (str.length < length) str = padString + str;
return str;
}
/**
* Convert a byte array to a hex string
*/
function bytesToHex(bytes) {
return bytes.map(function(x) {
return lpad(x.toString(16), '0', 2)
}).join('');
};
/**
* Convert a hex string to a byte array
*/
function hexToBytes(hex) {
return hex.match(/../g).map(function(x) {
return parseInt(x,16)
});
}
/**
* Convert a byte array to a base-64 string
*/
function bytesToBase64(bytes) {
var base64 = []
for (var i = 0; i < bytes.length; i += 3) {
var triplet = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2];
for (var j = 0; j < 4; j++) {
if (i * 8 + j * 6 <= bytes.length * 8) {
base64.push(base64map.charAt((triplet >>> 6 * (3 - j)) & 0x3F));
} else {
base64.push('=');
}
}
}
return base64.join('');
}
/**
* Convert a base-64 string to a byte array
*/
function base64ToBytes(base64) {
// Remove non-base-64 characters
base64 = base64.replace(/[^A-Z0-9+\/]/ig, '');
var bytes = [];
var imod4 = 0;
for (var i = 0; i < base64.length; imod4 = ++i % 4) {
if (!imod4) continue
bytes.push(
(
(base64map.indexOf(base64.charAt(i - 1)) & (Math.pow(2, -2 * imod4 + 8) - 1)) <<
(imod4 * 2)
) |
(base64map.indexOf(base64.charAt(i)) >>> (6 - imod4 * 2))
);
}
return bytes;
}
/**
* Hex only (allowing bin would be potentially risky, as 01010101 = \x01 * 4 or 85)
*/
function coerceToBytes(input) {
if (typeof input != 'string') return input
return hexToBytes(input);
}
function binToBytes(bin) {
return bin.match(/......../g).map(function(x) {
return parseInt(x,2)
});
}
function bytesToBin(bytes) {
return bytes.map(function(x) {
return lpad(x.toString(2), '0', 8)
}).join('');
}
function bytesToString(bytes) {
return bytes.map(function(x){
return String.fromCharCode(x)
}).join('');
}
function stringToBytes(string) {
return string.split('').map(function(x) {
return x.charCodeAt(0)
});
}
/**
* Create a byte array representing a number with the given length
*/
function numToBytes(num, bytes) {
if (bytes === undefined) bytes = 8;
if (bytes === 0) return [];
return [num % 256].concat(numToBytes(Math.floor(num / 256), bytes - 1));
}
/**
* Convert a byte array to the number that it represents
*/
function bytesToNum(bytes) {
if (bytes.length === 0) return 0;
return bytes[0] + 256 * bytesToNum(bytes.slice(1));
}
/**
* Turn an integer into a "var_int".
*
* "var_int" is a variable length integer used by Bitcoin's binary format.
*
* Returns a byte array.
*/
function numToVarInt(num) {
if (num < 253) return [num];
if (num < 65536) return [253].concat(numToBytes(num, 2));
if (num < 4294967296) return [254].concat(numToBytes(num, 4));
return [255].concat(numToBytes(num, 8));
}
function bytesToWords(bytes) {
var words = [];
for (var i = 0, b = 0; i < bytes.length; i++, b += 8) {
words[b >>> 5] |= bytes[i] << (24 - b % 32);
}
return words;
}
function wordsToBytes(words) {
var bytes = [];
for (var b = 0; b < words.length * 32; b += 8) {
bytes.push((words[b >>> 5] >>> (24 - b % 32)) & 0xFF);
}
return bytes;
}
function bytesToWordArray(bytes) {
return new WordArray.init(bytesToWords(bytes), bytes.length)
}
function wordArrayToBytes(wordArray) {
return wordsToBytes(wordArray.words)
}
module.exports = {
lpad: lpad,
bytesToHex: bytesToHex,
hexToBytes: hexToBytes,
bytesToBase64: bytesToBase64,
base64ToBytes: base64ToBytes,
coerceToBytes: coerceToBytes,
binToBytes: binToBytes,
bytesToBin: bytesToBin,
bytesToString: bytesToString,
stringToBytes: stringToBytes,
numToBytes: numToBytes,
bytesToNum: bytesToNum,
numToVarInt: numToVarInt,
bytesToWords: bytesToWords,
wordsToBytes: wordsToBytes,
bytesToWordArray: bytesToWordArray,
wordArrayToBytes: wordArrayToBytes
}