166 lines
6.8 KiB
HTML
166 lines
6.8 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<title>JSDoc: Source: pow.js</title>
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<h1 class="page-title">Source: pow.js</h1>
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<section>
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<article>
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<pre class="prettyprint source linenums"><code>/**
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* Implements proof of work.
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* @see {@link https://bitmessage.org/wiki/Proof_of_work}
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* @module bitmessage/pow
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*/
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"use strict";
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var objectAssign = Object.assign || require("object-assign");
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var bmcrypto = require("./crypto");
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var platform = require("./platform");
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var util = require("./_util");
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/**
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* Calculate target.
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* @param {Object} opts - Target options
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* @param {number} opts.ttl - Time to live of the message in seconds
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* @param {number} opts.payloadLength - Length of the message payload
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* (with nonce)
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* @param {Buffer} opts.payload - ...or payload itself
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* @param {number=} opts.nonceTrialsPerByte - This number is the average
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* number of nonce trials a node will have to perform to meet the Proof
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* of Work requirement. 1000 is the network minimum so any lower values
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* will be automatically raised to 1000.
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* @param {number=} opts.payloadLengthExtraBytes - This number is added
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* to the data length to make sending small messages more difficult.
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* 1000 is the network minimum so any lower values will be automatically
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* raised to 1000.
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* @return {number} Target.
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* @function
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* @static
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*/
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// Just a wrapper around platform-specific implementation.
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var getTarget = exports.getTarget = function(opts) {
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var payloadLength = opts.payloadLength || opts.payload.length;
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return platform.getTarget({
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ttl: opts.ttl,
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payloadLength: payloadLength,
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nonceTrialsPerByte: util.getTrials(opts),
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payloadLengthExtraBytes: util.getExtraBytes(opts),
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});
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};
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/**
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* Check a POW.
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* @param {Object} opts - Proof of work options
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* @param {number} opts.target - Proof of work target or pass
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* [getTarget]{@link module:bitmessage/pow.getTarget} options to `opts`
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* to compute it
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* @param {Buffer} opts.payload - Message payload (with nonce)
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* @param {(number|Buffer)} opts.nonce - ...or already derived nonce
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* @param {Buffer} opts.initialHash - ...and initial hash
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* @return {boolean} Is the proof of work sufficient.
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*/
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exports.check = function(opts) {
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var initialHash;
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var nonce;
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var target = opts.target;
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if (target === undefined) {
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target = getTarget(opts);
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}
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if (opts.payload) {
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nonce = opts.payload.slice(0, 8);
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initialHash = bmcrypto.sha512(opts.payload.slice(8));
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} else {
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if (typeof opts.nonce === "number") {
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nonce = new Buffer(8);
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// High 32 bits.
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nonce.writeUInt32BE(Math.floor(opts.nonce / 4294967296), 0, true);
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// Low 32 bits.
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nonce.writeUInt32BE(opts.nonce % 4294967296, 4, true);
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} else {
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nonce = opts.nonce;
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}
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initialHash = opts.initialHash;
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}
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var targetHi = Math.floor(target / 4294967296);
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var targetLo = target % 4294967296;
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var dataToHash = Buffer.concat([nonce, initialHash]);
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var resultHash = bmcrypto.sha512(bmcrypto.sha512(dataToHash));
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var trialHi = resultHash.readUInt32BE(0, true);
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if (trialHi > targetHi) {
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return false;
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} else if (trialHi < targetHi) {
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return true;
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} else {
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var trialLo = resultHash.readUInt32BE(4, true);
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return trialLo <= targetLo;
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}
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};
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/**
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* Do a POW.
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* @param {Object} opts - Proof of work options
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* @param {Buffer} opts.data - Object message payload without nonce to
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* get the initial hash from
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* @param {Buffer} opts.initialHash - ...or already computed initial
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* hash
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* @param {number} opts.target - POW target
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* @param {number=} opts.poolSize - POW calculation pool size (by
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* default equals to number of cores)
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* @return {Promise.<number>} A promise that contains computed nonce for
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* the given target when fulfilled.
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*/
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exports.doAsync = function(opts) {
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var initialHash;
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if (opts.data) {
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initialHash = bmcrypto.sha512(opts.data);
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} else {
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initialHash = opts.initialHash;
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}
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opts = objectAssign({}, opts, {initialHash: initialHash});
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return platform.pow(opts);
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};
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</code></pre>
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</article>
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</section>
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</div>
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<nav>
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<h2><a href="index.html">Home</a></h2><h3>Modules</h3><ul><li><a href="module-bitmessage.html">bitmessage</a></li><li><a href="module-bitmessage_address.html">bitmessage/address</a></li><li><a href="module-bitmessage_crypto.html">bitmessage/crypto</a></li><li><a href="module-bitmessage_messages.html">bitmessage/messages</a></li><li><a href="module-bitmessage_objects.html">bitmessage/objects</a></li><li><a href="module-bitmessage_pow.html">bitmessage/pow</a></li><li><a href="module-bitmessage_structs.html">bitmessage/structs</a></li><li><a href="module-bitmessage_user-agent.html">bitmessage/user-agent</a></li><li><a href="module-bitmessage_wif.html">bitmessage/wif</a></li></ul><h3>Classes</h3><ul><li><a href="module-bitmessage_address.Address.html">Address</a></li><li><a href="module-bitmessage_structs.PubkeyBitfield.html">PubkeyBitfield</a></li><li><a href="module-bitmessage_structs.ServicesBitfield.html">ServicesBitfield</a></li></ul><h3>Namespaces</h3><ul><li><a href="module-bitmessage_messages.addr.html">addr</a></li><li><a href="module-bitmessage_messages.error.html">error</a></li><li><a href="module-bitmessage_messages.getdata.html">getdata</a></li><li><a href="module-bitmessage_messages.inv.html">inv</a></li><li><a href="module-bitmessage_messages.version.html">version</a></li><li><a href="module-bitmessage_objects.broadcast.html">broadcast</a></li><li><a href="module-bitmessage_objects.getpubkey.html">getpubkey</a></li><li><a href="module-bitmessage_objects.msg.html">msg</a></li><li><a href="module-bitmessage_objects.pubkey.html">pubkey</a></li><li><a href="module-bitmessage_structs.encrypted.html">encrypted</a></li><li><a href="module-bitmessage_structs.inv_vect.html">inv_vect</a></li><li><a href="module-bitmessage_structs.message.html">message</a></li><li><a href="module-bitmessage_structs.net_addr.html">net_addr</a></li><li><a href="module-bitmessage_structs.object.html">object</a></li><li><a href="module-bitmessage_structs.var_int.html">var_int</a></li><li><a href="module-bitmessage_structs.var_int_list.html">var_int_list</a></li><li><a href="module-bitmessage_structs.var_str.html">var_str</a></li></ul>
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Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.4.0-dev</a> on Sat Feb 28 2015 22:57:02 GMT+0300 (MSK)
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