154 lines
2.8 KiB
JavaScript
154 lines
2.8 KiB
JavaScript
/*!
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* sigcache.js - signature cache for bcoin
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* Copyright (c) 2014-2017, Christopher Jeffrey (MIT License).
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* https://github.com/bcoin-org/bcoin
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*/
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'use strict';
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const assert = require('assert');
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const util = require('../utils/util');
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const secp256k1 = require('../crypto/secp256k1');
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/**
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* Signature cache.
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* @alias module:script.SigCache
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* @constructor
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* @param {Number} [size=10000]
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* @property {Number} size
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* @property {Hash[]} keys
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* @property {Object} valid
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*/
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function SigCache(size) {
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if (!(this instanceof SigCache))
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return new SigCache(size);
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if (size == null)
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size = 10000;
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assert(util.isNumber(size));
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assert(size >= 0);
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this.size = size;
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this.keys = [];
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this.valid = new Map();
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}
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/**
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* Resize the sigcache.
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* @param {Number} size
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*/
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SigCache.prototype.resize = function resize(size) {
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assert(util.isNumber(size));
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assert(size >= 0);
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this.size = size;
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this.keys.length = 0;
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this.valid.clear();
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};
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/**
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* Add item to the sigcache.
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* Potentially evict a random member.
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* @param {Hash} hash - Sig hash.
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* @param {Buffer} sig
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* @param {Buffer} key
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*/
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SigCache.prototype.add = function add(hash, sig, key) {
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if (this.size === 0)
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return;
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this.valid.set(hash, new SigCacheEntry(sig, key));
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if (this.keys.length >= this.size) {
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let i = Math.floor(Math.random() * this.keys.length);
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let k = this.keys[i];
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this.valid.delete(k);
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this.keys[i] = hash;
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} else {
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this.keys.push(hash);
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}
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};
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/**
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* Test whether the sig exists.
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* @param {Hash} hash - Sig hash.
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* @param {Buffer} sig
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* @param {Buffer} key
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* @returns {Boolean}
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*/
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SigCache.prototype.has = function has(hash, sig, key) {
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let entry = this.valid.get(hash);
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if (!entry)
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return false;
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return entry.equal(sig, key);
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};
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/**
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* Verify a signature, testing
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* it against the cache first.
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* @param {Buffer} msg
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* @param {Buffer} sig
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* @param {Buffer} key
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* @returns {Boolean}
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*/
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SigCache.prototype.verify = function verify(msg, sig, key) {
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let hash, result;
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if (this.size === 0)
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return secp256k1.verify(msg, sig, key);
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hash = msg.toString('hex');
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if (this.has(hash, sig, key))
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return true;
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result = secp256k1.verify(msg, sig, key);
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if (!result)
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return false;
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this.add(hash, sig, key);
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return true;
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};
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/**
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* Signature cache entry.
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* @constructor
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* @ignore
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* @param {Buffer} sig
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* @param {Buffer} key
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* @property {Buffer} sig
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* @property {Buffer} key
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*/
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function SigCacheEntry(sig, key) {
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this.sig = Buffer.from(sig);
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this.key = Buffer.from(key);
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}
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/**
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* Compare an entry to a sig and key.
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* @param {Buffer} sig
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* @param {Buffer} key
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* @returns {Boolean}
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*/
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SigCacheEntry.prototype.equal = function equal(sig, key) {
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return this.sig.equals(sig) && this.key.equals(key);
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};
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/*
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* Expose
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*/
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module.exports = SigCache;
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