var crypto = require('crypto'); var scmpCompare = require('./lib/scmpCompare'); /** * Does a constant-time Buffer comparison by not short-circuiting * on first sign of non-equivalency. * * @param {Buffer} a The first Buffer to be compared against the second * @param {Buffer} b The second Buffer to be compared against the first * @return {Boolean} */ module.exports = function scmp (a, b) { // check that both inputs are buffers if (!Buffer.isBuffer(a) || !Buffer.isBuffer(b)) { throw new Error('Both scmp args must be Buffers'); } // return early here if buffer lengths are not equal since timingSafeEqual // will throw if buffer lengths are not equal if (a.length !== b.length) { return false; } // use crypto.timingSafeEqual if available (since Node.js v6.6.0), // otherwise use our own scmp-internal function. if (crypto.timingSafeEqual) { return crypto.timingSafeEqual(a, b); } return scmpCompare(a, b); };