stupid-miner/js/cryptutil.js

var crypto = require("crypto");

exports.createCoinbase = createCoinbase;
exports.createCbHash = createCbHash;
exports.buildMerkleRoot = buildMerkleRoot;
exports.doublesha = doublesha;
exports.incbufBE = incbufBE;

/* Create a coinbase buffer.
 *
 * Args:
 *     cb1, cb2: Buffer, coinbase parts 1 and 2
 *     ex1, ex2: Buffer, extranounce 1 and 2
 *
 * Returns:
 *     Buffer, a complete coinbase
 */
function createCoinbase(ex1, ex2, cb1, cb2) {
	return Buffer.concat([ cb1, ex1, ex2, cb2 ]);
}

/* Create a coinbase hash.
 *
 * Args:
 *     coinbase: Buffer, the coinbase
 *
 * Returns:
 *     Buffer, the cbHashBin
 */
function createCbHash(coinbase) {
	return doublesha(coinbase);
}

/* Build a merkle root from a merkle branch and a coinbase hash.
 *
 * Returns:
 *     Buffer, the merkle root
 *
 * Args:
 *     merkleBranch: Array, hex encoded hashes
 *     cbHash: Buffer, the coinbase hash
 */
function buildMerkleRoot(merkleBranch, cbHash) {
	var root = cbHashBin
	for (var i in merkleBranch) {
		var h = Buffer.from(merkleBranch[i], "hex");
		root = doublesha(Buffer.concat(root, h));
	}

	return root;
}

/* Run sha256 twice on a buffer.
 *
 * Returns:
 *     Buffer, the double-sha256'd buffer
 *
 * Args:
 *     buf: Buffer, will be double-sha256'd
 */
function doublesha(buf) {
	var tmp = crypto.createHash("sha256").update(buf).digest();
	return crypto.createHash("sha256").update(tmp).digest();
}

/* Increment a buffer.
 *
 * Args:
 *     buf: Buffer, will be incremented.
 */
function incbufBE(buf) {
	for (var i = buf.length - 1; i >= 0; --i) {
		if (buf[i]++ !== 255)
			break;
	}
}