bitmessage-js/lib/platform.js
2015-01-12 21:27:14 +03:00

72 lines
1.8 KiB
JavaScript

/**
* Node.js implementation of platform-specific routines.
*/
"use strict";
var os = require("os");
var crypto = require("crypto");
var promise = typeof Promise === "undefined" ?
require("es6-promise").Promise :
Promise;
var bignum = require("bignum");
var assert = require("./util").assert;
var worker = require("./worker");
var createHash = crypto.createHash;
exports.sha512 = function(buf) {
return createHash("sha512").update(buf).digest();
};
exports.sha256 = function(buf) {
return createHash("sha256").update(buf).digest();
};
exports.ripemd160 = function(buf) {
return createHash("ripemd160").update(buf).digest();
};
exports.randomBytes = crypto.randomBytes;
// 2^64.
var B64 = bignum("18446744073709551616");
// NOTE(Kagami): We can't calculate entire target in JavaScript but the
// result can be represented in native number type without losing
// precision (targets mainly much less than 2^53).
exports.getTarget = function(opts) {
// Calculate it bottom-up, right-to-left.
var length = bignum(opts.payloadLength)
// To account for the nonce which we will append later.
.add(8)
.add(opts.payloadLengthExtraBytes);
var denominator = bignum(opts.ttl)
.mul(length)
.div(65536)
.add(length)
.mul(opts.nonceTrialsPerByte);
var target = B64.div(denominator).toNumber();
assert(target <= 9007199254740991, "Unsafe target");
return target;
};
exports.pow = function(opts) {
var poolSize = opts.poolSize || os.cpus().length;
// TODO(Kagami): Allow to cancel a POW (see `platform.browser.js`).
return new promise(function(resolve, reject) {
worker.powAsync(
poolSize,
opts.target,
opts.initialHash,
function(err, nonce) {
if (err) {
reject(err);
} else {
resolve(nonce);
}
}
);
});
};