verify.js
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// Copyright 2015 Joyent, Inc.
var assert = require('assert-plus');
var crypto = require('crypto');
var sshpk = require('sshpk');
var utils = require('./utils');
var HASH_ALGOS = utils.HASH_ALGOS;
var PK_ALGOS = utils.PK_ALGOS;
var InvalidAlgorithmError = utils.InvalidAlgorithmError;
var HttpSignatureError = utils.HttpSignatureError;
var validateAlgorithm = utils.validateAlgorithm;
///--- Exported API
module.exports = {
/**
* Verify RSA/DSA signature against public key. You are expected to pass in
* an object that was returned from `parse()`.
*
* @param {Object} parsedSignature the object you got from `parse`.
* @param {String} pubkey RSA/DSA private key PEM.
* @return {Boolean} true if valid, false otherwise.
* @throws {TypeError} if you pass in bad arguments.
* @throws {InvalidAlgorithmError}
*/
verifySignature: function verifySignature(parsedSignature, pubkey) {
assert.object(parsedSignature, 'parsedSignature');
if (typeof (pubkey) === 'string' || Buffer.isBuffer(pubkey))
pubkey = sshpk.parseKey(pubkey);
assert.ok(sshpk.Key.isKey(pubkey, [1, 1]), 'pubkey must be a sshpk.Key');
var alg = validateAlgorithm(parsedSignature.algorithm);
if (alg[0] === 'hmac' || alg[0] !== pubkey.type)
return (false);
var v = pubkey.createVerify(alg[1]);
v.update(parsedSignature.signingString);
return (v.verify(parsedSignature.params.signature, 'base64'));
},
/**
* Verify HMAC against shared secret. You are expected to pass in an object
* that was returned from `parse()`.
*
* @param {Object} parsedSignature the object you got from `parse`.
* @param {String} secret HMAC shared secret.
* @return {Boolean} true if valid, false otherwise.
* @throws {TypeError} if you pass in bad arguments.
* @throws {InvalidAlgorithmError}
*/
verifyHMAC: function verifyHMAC(parsedSignature, secret) {
assert.object(parsedSignature, 'parsedHMAC');
assert.string(secret, 'secret');
var alg = validateAlgorithm(parsedSignature.algorithm);
if (alg[0] !== 'hmac')
return (false);
var hashAlg = alg[1].toUpperCase();
var hmac = crypto.createHmac(hashAlg, secret);
hmac.update(parsedSignature.signingString);
/*
* Now double-hash to avoid leaking timing information - there's
* no easy constant-time compare in JS, so we use this approach
* instead. See for more info:
* https://www.isecpartners.com/blog/2011/february/double-hmac-
* verification.aspx
*/
var h1 = crypto.createHmac(hashAlg, secret);
h1.update(hmac.digest());
h1 = h1.digest();
var h2 = crypto.createHmac(hashAlg, secret);
h2.update(new Buffer(parsedSignature.params.signature, 'base64'));
h2 = h2.digest();
/* Node 0.8 returns strings from .digest(). */
if (typeof (h1) === 'string')
return (h1 === h2);
/* And node 0.10 lacks the .equals() method on Buffers. */
if (Buffer.isBuffer(h1) && !h1.equals)
return (h1.toString('binary') === h2.toString('binary'));
return (h1.equals(h2));
}
};