40 lines
857 B
JavaScript
40 lines
857 B
JavaScript
/*!
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* ccmp.js - constant-time compare for bcoin
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* Copyright (c) 2016-2017, 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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/**
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* memcmp in constant time (can only return true or false).
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* This protects us against timing attacks when
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* comparing an input against a secret string.
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* @alias module:crypto.ccmp
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* @see https://cryptocoding.net/index.php/Coding_rules
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* @see `$ man 3 memcmp` (NetBSD's consttime_memequal)
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* @param {Buffer} a
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* @param {Buffer} b
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* @returns {Boolean}
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*/
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module.exports = function ccmp(a, b) {
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let res;
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if (!Buffer.isBuffer(a))
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return false;
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if (!Buffer.isBuffer(b))
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return false;
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if (b.length === 0)
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return a.length === 0;
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res = a.length ^ b.length;
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for (let i = 0; i < a.length; i++)
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res |= a[i] ^ b[i % b.length];
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return res === 0;
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};
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