Functions to encrypt and decrypt ECDH keys
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Ismael Bejarano
Sanjana Rajan
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673151ec87
commit
585a2bd69d
129
src/crypto/public_key/elliptic/ecdh.js
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129
src/crypto/public_key/elliptic/ecdh.js
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// OpenPGP.js - An OpenPGP implementation in javascript
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// Copyright (C) 2015-2016 Decentral
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 3.0 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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// Key encryption and decryption for RFC 6637 ECDH
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/**
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* @requires crypto/hash
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* @requires crypto/cipher
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* @requires crypto/rfc3394
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* @requires crypto/public_key/elliptic/curves
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* @requires crypto/public_key/jsbn
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* @requires type/oid
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* @requires type/kdf_params
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* @requires enums
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* @requires util
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* @module crypto/public_key/elliptic/ecdh
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*/
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'use strict';
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import BigInteger from '../jsbn.js';
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import curves from './curves.js';
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import cipher from '../../cipher';
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import hash from '../../hash';
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import rfc3394 from '../../rfc3394.js';
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import enums from '../../../enums.js';
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import util from '../../../util.js';
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import type_kdf_params from '../../../type/kdf_params.js';
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import type_oid from '../../../type/oid.js';
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function hex2Uint8Array(hex) {
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var result = new Uint8Array(hex.length/2);
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for (var k=0; k<hex.length/2; k++) {
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result[k] = parseInt(hex.substr(2*k, 2), 16);
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}
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return result;
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}
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// Build Param for ECDH algorithm (RFC 6637)
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function buildEcdhParam(public_algo, oid, cipher_algo, hash_algo, fingerprint) {
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oid = new type_oid(oid);
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const kdf_params = new type_kdf_params(hash_algo, cipher_algo);
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return util.concatUint8Array([
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oid.write(),
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new Uint8Array([public_algo]),
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kdf_params.write(),
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util.str2Uint8Array("Anonymous Sender "),
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fingerprint
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]);
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}
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// Key Derivation Function (RFC 6637)
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function kdf(hash_algo, X, length, param) {
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return hash.digest(hash_algo, util.concatUint8Array([
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new Uint8Array([0, 0, 0, 1]),
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new Uint8Array(X),
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param
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])).subarray(0, length);
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}
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/**
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* Encrypt and wrap a session key
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*
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* @param {String} oid Oid of the curve to use
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* @param {Enums} cipher_algo Symmetric cipher to use
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* @param {Enums} hash_algo Hash to use
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* @param {Uint8Array} m Value derived from session key (RFC 6637)
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* @param {BigInteger} R Recipient public key
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* @param {String} fingerprint Recipient fingerprint
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* @return {{V: BigInteger, C: Uint8Array}} Returns ephemeral key and encoded session key
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*/
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function encrypt(oid, cipher_algo, hash_algo, m, R, fingerprint) {
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fingerprint = hex2Uint8Array(fingerprint);
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const param = buildEcdhParam(enums.publicKey.ecdh, oid, cipher_algo, hash_algo, fingerprint);
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const curve = curves.get(oid);
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cipher_algo = enums.read(enums.symmetric, cipher_algo);
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const v = curve.genKeyPair();
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R = curve.keyFromPublic(R.toByteArray());
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const S = v.derive(R);
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const Z = kdf(hash_algo, S, cipher[cipher_algo].keySize, param);
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const C = rfc3394.wrap(Z, m);
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return {
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V: new BigInteger(v.getPublic()),
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C: C
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};
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}
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/**
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* Decrypt and unwrap the value derived from session key
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*
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* @param {String} oid Curve oid
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* @param {Enums} cipher_algo Symmetric cipher to use
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* @param {Enums} hash_algo Hash algorithm to use
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* @param {BigInteger} V Public part of ephemeral key
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* @param {Uint8Array} C Encrypted and wrapped value derived from session key
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* @param {BigInteger} r Recipient private key
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* @param {String} fingerprint Recipient fingerprint
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* @return {Uint8Array} Value derived from session
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*/
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function decrypt(oid, cipher_algo, hash_algo, V, C, r, fingerprint) {
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fingerprint = hex2Uint8Array(fingerprint);
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const param = buildEcdhParam(enums.publicKey.ecdh, oid, cipher_algo, hash_algo, fingerprint);
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const curve = curves.get(oid);
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cipher_algo = enums.read(enums.symmetric, cipher_algo);
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V = curve.keyFromPublic(V.toByteArray());
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r = curve.keyFromPrivate(r.toByteArray());
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const S = r.derive(V);
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const Z = kdf(hash_algo, S, cipher[cipher_algo].keySize, param);
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return new BigInteger(rfc3394.unwrap(Z, C));
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}
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module.exports = {
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encrypt: encrypt,
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decrypt: decrypt
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};
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@ -19,6 +19,7 @@
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/**
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* @requires crypto/public_key/elliptic/curve
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* @requires crypto/public_key/elliptic/ecdh
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* @requires crypto/public_key/elliptic/ecdsa
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* @module crypto/public_key/elliptic
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*/
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@ -26,9 +27,11 @@
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'use strict';
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import {get, generate} from './curves.js';
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import ecdh from './ecdh.js';
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import ecdsa from './ecdsa.js';
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module.exports = {
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ecdh: ecdh,
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ecdsa: ecdsa,
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get: get,
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generate: generate
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@ -27,6 +27,7 @@ export default {
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rsa_sign: 3,
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elgamal: 16,
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dsa: 17,
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ecdh: 18,
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ecdsa: 19
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},
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@ -291,4 +291,58 @@ describe('Elliptic Curve Cryptography', function () {
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done();
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});
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});
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describe('ECDH key exchange', function () {
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var decrypt_message = function (oid, hash, cipher, priv, ephemeral, data, fingerprint) {
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if (typeof data === 'string') {
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data = openpgp.util.str2Uint8Array(data);
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} else {
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data = new Uint8Array(data);
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}
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return function () {
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var ecdh = elliptic_curves.ecdh;
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return ecdh.decrypt(
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oid,
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cipher,
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hash,
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bin2bi(ephemeral),
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data,
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bin2bi(priv),
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fingerprint
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);
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};
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};
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var secp256k1_value = new Uint8Array([
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0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
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var secp256k1_point = new Uint8Array([0x04,
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0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
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var secp256k1_data = new Uint8Array([
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
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it('Invalid curve oid', function (done) {
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var res = decrypt_message('', 2, 7, [], [], [], '');
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expect(res).to.throw(Error, /Not valid curve/);
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done();
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});
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it('Invalid ephemeral key', function (done) {
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var res = decrypt_message('secp256k1', 2, 7, [], [], [], '');
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expect(res).to.throw(Error, /Unknown point format/);
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done();
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});
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it('Invalid key data integrity', function (done) {
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var res = decrypt_message('secp256k1', 2, 7, secp256k1_value, secp256k1_point, secp256k1_data, '');
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expect(res).to.throw(Error, /Key Data Integrity failed/);
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done();
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});
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});
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});
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