222 lines
10 KiB
HTML
222 lines
10 KiB
HTML
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<title>JSDoc: Source: crypto/public_key/dsa.js</title>
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<h1 class="page-title">Source: crypto/public_key/dsa.js</h1>
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<section>
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<article>
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<pre class="prettyprint source"><code>// GPG4Browsers - An OpenPGP implementation in javascript
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// Copyright (C) 2011 Recurity Labs GmbH
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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 2.1 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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//
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// A Digital signature algorithm implementation
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/**
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* @requires crypto/hash
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* @requires crypto/public_key/jsbn
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* @requires crypto/random
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* @requires util
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* @module crypto/public_key/dsa
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*/
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var BigInteger = require('./jsbn.js'),
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random = require('../random.js'),
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hashModule = require('../hash'),
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util = require('../../util'),
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config = require('../../config');
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function DSA() {
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// s1 = ((g**s) mod p) mod q
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// s1 = ((s**-1)*(sha-1(m)+(s1*x) mod q)
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function sign(hashalgo, m, g, p, q, x) {
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// If the output size of the chosen hash is larger than the number of
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// bits of q, the hash result is truncated to fit by taking the number
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// of leftmost bits equal to the number of bits of q. This (possibly
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// truncated) hash function result is treated as a number and used
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// directly in the DSA signature algorithm.
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var hashed_data = util.getLeftNBits(hashModule.digest(hashalgo, m), q.bitLength());
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var hash = new BigInteger(util.hexstrdump(hashed_data), 16);
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var k = random.getRandomBigIntegerInRange(BigInteger.ONE.add(BigInteger.ONE), q.subtract(BigInteger.ONE));
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var s1 = (g.modPow(k, p)).mod(q);
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var s2 = (k.modInverse(q).multiply(hash.add(x.multiply(s1)))).mod(q);
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var result = new Array();
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result[0] = s1.toMPI();
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result[1] = s2.toMPI();
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return result;
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}
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function select_hash_algorithm(q) {
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var usersetting = config.prefer_hash_algorithm;
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/*
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* 1024-bit key, 160-bit q, SHA-1, SHA-224, SHA-256, SHA-384, or SHA-512 hash
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* 2048-bit key, 224-bit q, SHA-224, SHA-256, SHA-384, or SHA-512 hash
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* 2048-bit key, 256-bit q, SHA-256, SHA-384, or SHA-512 hash
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* 3072-bit key, 256-bit q, SHA-256, SHA-384, or SHA-512 hash
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*/
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switch (Math.round(q.bitLength() / 8)) {
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case 20:
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// 1024 bit
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if (usersetting != 2 &&
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usersetting > 11 &&
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usersetting != 10 &&
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usersetting < 8)
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return 2; // prefer sha1
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return usersetting;
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case 28:
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// 2048 bit
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if (usersetting > 11 &&
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usersetting < 8)
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return 11;
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return usersetting;
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case 32:
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// 4096 bit // prefer sha224
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if (usersetting > 10 &&
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usersetting < 8)
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return 8; // prefer sha256
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return usersetting;
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default:
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util.print_debug("DSA select hash algorithm: returning null for an unknown length of q");
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return null;
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}
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}
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this.select_hash_algorithm = select_hash_algorithm;
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function verify(hashalgo, s1, s2, m, p, q, g, y) {
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var hashed_data = util.getLeftNBits(hashModule.digest(hashalgo, m), q.bitLength());
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var hash = new BigInteger(util.hexstrdump(hashed_data), 16);
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if (BigInteger.ZERO.compareTo(s1) > 0 ||
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s1.compareTo(q) > 0 ||
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BigInteger.ZERO.compareTo(s2) > 0 ||
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s2.compareTo(q) > 0) {
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util.print_debug("invalid DSA Signature");
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return null;
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}
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var w = s2.modInverse(q);
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var u1 = hash.multiply(w).mod(q);
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var u2 = s1.multiply(w).mod(q);
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return g.modPow(u1, p).multiply(y.modPow(u2, p)).mod(p).mod(q);
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}
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/*
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* unused code. This can be used as a start to write a key generator
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* function.
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function generateKey(bitcount) {
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var qi = new BigInteger(bitcount, primeCenterie);
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var pi = generateP(q, 512);
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var gi = generateG(p, q, bitcount);
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var xi;
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do {
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xi = new BigInteger(q.bitCount(), rand);
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} while (x.compareTo(BigInteger.ZERO) != 1 && x.compareTo(q) != -1);
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var yi = g.modPow(x, p);
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return {x: xi, q: qi, p: pi, g: gi, y: yi};
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}
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function generateP(q, bitlength, randomfn) {
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if (bitlength % 64 != 0) {
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return false;
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}
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var pTemp;
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var pTemp2;
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do {
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pTemp = randomfn(bitcount, true);
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pTemp2 = pTemp.subtract(BigInteger.ONE);
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pTemp = pTemp.subtract(pTemp2.remainder(q));
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} while (!pTemp.isProbablePrime(primeCenterie) || pTemp.bitLength() != l);
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return pTemp;
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}
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function generateG(p, q, bitlength, randomfn) {
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var aux = p.subtract(BigInteger.ONE);
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var pow = aux.divide(q);
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var gTemp;
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do {
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gTemp = randomfn(bitlength);
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} while (gTemp.compareTo(aux) != -1 && gTemp.compareTo(BigInteger.ONE) != 1);
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return gTemp.modPow(pow, p);
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}
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function generateK(q, bitlength, randomfn) {
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var tempK;
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do {
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tempK = randomfn(bitlength, false);
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} while (tempK.compareTo(q) != -1 && tempK.compareTo(BigInteger.ZERO) != 1);
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return tempK;
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}
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function generateR(q,p) {
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k = generateK(q);
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var r = g.modPow(k, p).mod(q);
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return r;
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}
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function generateS(hashfn,k,r,m,q,x) {
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var hash = hashfn(m);
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s = (k.modInverse(q).multiply(hash.add(x.multiply(r)))).mod(q);
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return s;
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} */
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this.sign = sign;
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this.verify = verify;
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// this.generate = generateKey;
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}
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module.exports = DSA;
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</code></pre>
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</article>
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</section>
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<h2><a href="index.html">Index</a></h2><h3>Modules</h3><ul><li><a href="module-armor.html">armor</a></li><li><a href="module-cleartext.html">cleartext</a></li><li><a href="module-config.html">config</a></li><li><a href="config.html">config/config</a></li><li><a href="localStorage.html">config/localStorage</a></li><li><a href="module-crypto.html">crypto</a></li><li><a href="cfb.html">crypto/cfb</a></li><li><a href="cipher.html">crypto/cipher</a></li><li><a href="aes.html">crypto/cipher/aes</a></li><li><a href="blowfish.html">crypto/cipher/blowfish</a></li><li><a href="cast5.html">crypto/cipher/cast5</a></li><li><a href="des.html">crypto/cipher/des</a></li><li><a href="twofish.html">crypto/cipher/twofish</a></li><li><a href="crypto.html">crypto/crypto</a></li><li><a href="hash.html">crypto/hash</a></li><li><a href="md5.html">crypto/hash/md5</a></li><li><a href="ripe-md.html">crypto/hash/ripe-md</a></li><li><a href="sha.html">crypto/hash/sha</a></li><li><a href="pkcs1.html">crypto/pkcs1</a></li><li><a href="public_key.html">crypto/public_key</a></li><li><a href="dsa.html">crypto/public_key/dsa</a></li><li><a href="elgamal.html">crypto/public_key/elgamal</a></li><li><a href="jsbn.html">crypto/public_key/jsbn</a></li><li><a href="rsa.html">crypto/public_key/rsa</a></li><li><a href="random.html">crypto/random</a></li><li><a href="signature.html">crypto/signature</a></li><li><a href="armor.html">encoding/armor</a></li><li><a href="base64.html">encoding/base64</a></li><li><a href="module-enums.html">enums</a></li><li><a href="module-key.html">key</a></li><li><a href="module-keyid.html">keyid</a></li><li><a href="keyring.html">keyring/keyring</a></li><li><a href="localstore.html">keyring/localstore</a></li><li><a href="module-message.html">message</a></li><li><a href="module-mpi.html">mpi</a></li><li><a href="module-openpgp.html">openpgp</a></li><li><a href="module-packet.html">packet</a></li><li><a href="compressed.html">packet/compressed</a></li><li><a href="literal.html">packet/literal</a></li><li><a href="marker.html">packet/marker</a></li><li><a href="one_pass_signature.html">packet/one_pass_signature</a></li><li><a href="packet.html">packet/packet</a></li><li><a href="packetlist.html">packet/packetlist</a></li><li><a href="public_key_.html">packet/public_key</a></li><li><a href="public_key_encrypted_session_key.html">packet/public_key_encrypted_session_key</a></li><li><a href="public_subkey.html">packet/public_subkey</a></li><li><a href="secret_key.html">packet/secret_key</a></li><li><a href="secret_subkey.html">packet/secret_subkey</a></li><li><a href="signature_.html">packet/signature</a></li><li><a href="sym_encrypted_integrity_protected.html">packet/sym_encrypted_integrity_protected</a></li><li><a href="sym_encrypted_session_key.html">packet/sym_encrypted_session_key</a></li><li><a href="symmetrically_encrypted.html">packet/symmetrically_encrypted</a></li><li><a href="trust.html">packet/trust</a></li><li><a href="user_attribute.html">packet/user_attribute</a></li><li><a href="userid.html">packet/userid</a></li><li><a href="module-s2k.html">s2k</a></li><li><a href="keyid.html">type/keyid</a></li><li><a href="mpi.html">type/mpi</a></li><li><a href="s2k.html">type/s2k</a></li><li><a href="module-util.html">util</a></li><li><a href="util.html">util/util</a></li></ul><h3>Classes</h3><ul><li><a href="JXG.Util.html">Util</a></li><li><a href="module-cleartext-CleartextMessage.html">CleartextMessage</a></li><li><a href="module-key-Key.html">Key</a></li><li><a href="module-key-SubKey.html">SubKey</a></li><li><a href="module-key-User.html">User</a></li><li><a href="module-message-Message.html">Message</a></li></ul>
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