27ec74ba8a
The BigInteger class we're using supports negative integers and encodes them with a sign bit. Since in our application we are dealing with unsigned integers only, we need to disable this functionality by creating two wrapper functions toByteArrayUnsigned and fromByteArrayUnsigned.
68 lines
1.8 KiB
JavaScript
68 lines
1.8 KiB
JavaScript
(function () {
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var B58 = Bitcoin.Base58 = {
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alphabet: "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz",
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base: BigInteger.valueOf(58),
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/**
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* Convert a byte array to a base58-encoded string.
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*
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* Written by Mike Hearn for BitcoinJ.
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* Copyright (c) 2011 Google Inc.
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*
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* Ported to JavaScript by Stefan Thomas.
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*/
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encode: function (input) {
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console.log(input);
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// We prepend the input with a zero byte because the BigInteger
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// implementation treats it as a negative number if any of the
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// four most significant bits are set.
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var bi = BigInteger.fromByteArrayUnsigned(input);
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var chars = [];
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while (bi.compareTo(B58.base) >= 0) {
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var mod = bi.mod(B58.base);
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chars.unshift(B58.alphabet[mod.intValue()]);
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bi = bi.subtract(mod).divide(B58.base);
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}
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chars.unshift(B58.alphabet[bi.intValue()]);
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// Convert leading zeros too.
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for (var i = 0; i < input.length; i++) {
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if (input[i] == 0x00) {
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chars.unshift(B58.alphabet[0]);
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} else break;
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}
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s = chars.join('');
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return s;
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},
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/**
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* Convert a base58-encoded string to a byte array.
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*
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* Written by Mike Hearn for BitcoinJ.
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* Copyright (c) 2011 Google Inc.
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*
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* Ported to JavaScript by Stefan Thomas.
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*/
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decode: function (input) {
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bi = BigInteger.valueOf(0);
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var leadingZerosNum = 0;
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for (var i = input.length - 1; i >= 0; i--) {
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var alphaIndex = B58.alphabet.indexOf(input[i]);
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bi = bi.add(BigInteger.valueOf(alphaIndex)
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.multiply(B58.base.pow(input.length - 1 -i)));
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// This counts leading zero bytes
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if (input[i] == "1") leadingZerosNum++;
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else leadingZerosNum = 0;
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}
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var bytes = bi.toByteArrayUnsigned();
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// Add leading zeros
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while (leadingZerosNum-- > 0) bytes.unshift(0);
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return bytes;
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}
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};
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})();
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