48 lines
1.2 KiB
JavaScript
48 lines
1.2 KiB
JavaScript
/**
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* Node.js implementation of platform-specific routines.
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*/
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"use strict";
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var crypto = require("crypto");
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var bignum = require("bignum");
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var assert = require("./util").assert;
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var createHash = crypto.createHash;
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exports.sha512 = function(buf) {
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return createHash("sha512").update(buf).digest();
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};
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exports.sha256 = function(buf) {
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return createHash("sha256").update(buf).digest();
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};
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exports.ripemd160 = function(buf) {
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return createHash("ripemd160").update(buf).digest();
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};
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exports.randomBytes = crypto.randomBytes;
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// 2^64.
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var B64 = bignum("18446744073709551616");
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// NOTE(Kagami): We can't calculate entire target in JavaScript but the
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// result can be represented in native number type without losing
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// precision (targets mainly much less than 2^53).
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exports.getTarget = function(opts) {
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// Calculate it bottom-up, right-to-left.
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var length = bignum(opts.payloadLength)
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// To account for the nonce which we will append later.
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.add(8)
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.add(opts.payloadLengthExtraBytes);
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var denominator = bignum(opts.ttl)
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.mul(length)
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.div(65536)
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.add(length)
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.mul(opts.nonceTrialsPerByte);
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var target = B64.div(denominator).toNumber();
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assert(target <= 9007199254740991, "Unsafe target");
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return target;
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};
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