71 lines
1.9 KiB
JavaScript
71 lines
1.9 KiB
JavaScript
/// Implements Bitcoin's feature for signing arbitrary messages.
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var Crypto = require('./crypto-js/crypto');
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var ecdsa = require('./ecdsa');
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var conv = require('./convert');
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var util = require('./util');
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var Message = {};
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Message.magicPrefix = "Bitcoin Signed Message:\n";
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Message.makeMagicMessage = function (message) {
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var magicBytes = Crypto.charenc.UTF8.stringToBytes(Message.magicPrefix);
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var messageBytes = Crypto.charenc.UTF8.stringToBytes(message);
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var buffer = [];
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buffer = buffer.concat(util.numToVarInt(magicBytes.length));
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buffer = buffer.concat(magicBytes);
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buffer = buffer.concat(util.numToVarInt(messageBytes.length));
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buffer = buffer.concat(messageBytes);
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return buffer;
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};
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Message.getHash = function (message) {
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var buffer = Message.makeMagicMessage(message);
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return Crypto.SHA256(Crypto.SHA256(buffer, {asBytes: true}), {asBytes: true});
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};
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Message.signMessage = function (key, message, compressed) {
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var hash = Message.getHash(message);
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var sig = key.sign(hash);
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var obj = ecdsa.parseSig(sig);
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var address = key.getBitcoinAddress().toString();
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var i = ecdsa.calcPubkeyRecoveryParam(address, obj.r, obj.s, hash);
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i += 27;
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if (compressed) i += 4;
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var rBa = obj.r.toByteArrayUnsigned();
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var sBa = obj.s.toByteArrayUnsigned();
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// Pad to 32 bytes per value
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while (rBa.length < 32) rBa.unshift(0);
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while (sBa.length < 32) sBa.unshift(0);
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sig = [i].concat(rBa).concat(sBa);
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return conv.bytesToBase64(sig);
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};
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Message.verifyMessage = function (address, sig, message) {
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sig = conv.base64ToBytes(sig);
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sig = ecdsa.parseSigCompact(sig);
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var hash = Message.getHash(message);
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var isCompressed = !!(sig.i & 4);
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var pubKey = ecdsa.recoverPubKey(sig.r, sig.s, hash, sig.i);
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pubKey.setCompressed(isCompressed);
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var expectedAddress = pubKey.getBitcoinAddress().toString();
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return (address === expectedAddress);
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};
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module.exports = Message;
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