351 lines
18 KiB
HTML
351 lines
18 KiB
HTML
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<title>JSDoc: Source: crypto/cfb.js</title>
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<h1 class="page-title">Source: crypto/cfb.js</h1>
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<section>
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<article>
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<pre class="prettyprint source"><code>// Modified by Recurity Labs GmbH
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// modified version of http://www.hanewin.net/encrypt/PGdecode.js:
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/* OpenPGP encryption using RSA/AES
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* Copyright 2005-2006 Herbert Hanewinkel, www.haneWIN.de
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* version 2.0, check www.haneWIN.de for the latest version
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* This software is provided as-is, without express or implied warranty.
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* Permission to use, copy, modify, distribute or sell this software, with or
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* without fee, for any purpose and by any individual or organization, is hereby
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* granted, provided that the above copyright notice and this paragraph appear
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* in all copies. Distribution as a part of an application or binary must
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* include the above copyright notice in the documentation and/or other
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* materials provided with the application or distribution.
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*/
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/**
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* @requires crypto/cipher
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* @requires util
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* @module crypto/cfb
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*/
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var util = require('../util'),
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cipher = require('./cipher');
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module.exports = {
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/**
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* This function encrypts a given with the specified prefixrandom
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* using the specified blockcipher to encrypt a message
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* @param {String} prefixrandom random bytes of block_size length provided
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* as a string to be used in prefixing the data
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* @param {String} cipherfn the algorithm cipher class to encrypt
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* data in one block_size encryption, @see module:crypto/cipher.
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* @param {String} plaintext data to be encrypted provided as a string
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* @param {String} key binary string representation of key to be used to encrypt the plaintext.
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* This will be passed to the cipherfn
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* @param {Boolean} resync a boolean value specifying if a resync of the
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* IV should be used or not. The encrypteddatapacket uses the
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* "old" style with a resync. Encryption within an
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* encryptedintegrityprotecteddata packet is not resyncing the IV.
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* @return {String} a string with the encrypted data
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*/
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encrypt: function(prefixrandom, cipherfn, plaintext, key, resync) {
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cipherfn = new cipher[cipherfn](key);
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var block_size = cipherfn.blockSize;
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var FR = new Array(block_size);
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var FRE = new Array(block_size);
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prefixrandom = prefixrandom + prefixrandom.charAt(block_size - 2) + prefixrandom.charAt(block_size - 1);
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util.print_debug("prefixrandom:" + util.hexstrdump(prefixrandom));
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var ciphertext = "";
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var i;
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// 1. The feedback register (FR) is set to the IV, which is all zeros.
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for (i = 0; i < block_size; i++) FR[i] = 0;
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// 2. FR is encrypted to produce FRE (FR Encrypted). This is the
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// encryption of an all-zero value.
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FRE = cipherfn.encrypt(FR);
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// 3. FRE is xored with the first BS octets of random data prefixed to
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// the plaintext to produce C[1] through C[BS], the first BS octets
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// of ciphertext.
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for (i = 0; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ prefixrandom.charCodeAt(i));
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// 4. FR is loaded with C[1] through C[BS].
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for (i = 0; i < block_size; i++) FR[i] = ciphertext.charCodeAt(i);
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// 5. FR is encrypted to produce FRE, the encryption of the first BS
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// octets of ciphertext.
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FRE = cipherfn.encrypt(FR);
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// 6. The left two octets of FRE get xored with the next two octets of
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// data that were prefixed to the plaintext. This produces C[BS+1]
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// and C[BS+2], the next two octets of ciphertext.
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ciphertext += String.fromCharCode(FRE[0] ^ prefixrandom.charCodeAt(block_size));
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ciphertext += String.fromCharCode(FRE[1] ^ prefixrandom.charCodeAt(block_size + 1));
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if (resync) {
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// 7. (The resync step) FR is loaded with C3-C10.
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for (i = 0; i < block_size; i++) FR[i] = ciphertext.charCodeAt(i + 2);
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} else {
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for (i = 0; i < block_size; i++) FR[i] = ciphertext.charCodeAt(i);
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}
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// 8. FR is encrypted to produce FRE.
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FRE = cipherfn.encrypt(FR, key);
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if (resync) {
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// 9. FRE is xored with the first 8 octets of the given plaintext, now
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// that we have finished encrypting the 10 octets of prefixed data.
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// This produces C11-C18, the next 8 octets of ciphertext.
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for (i = 0; i < block_size; i++)
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ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(i));
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for (n = block_size + 2; n < plaintext.length; n += block_size) {
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// 10. FR is loaded with C11-C18
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for (i = 0; i < block_size; i++) FR[i] = ciphertext.charCodeAt(n + i);
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// 11. FR is encrypted to produce FRE.
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FRE = cipherfn.encrypt(FR);
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// 12. FRE is xored with the next 8 octets of plaintext, to produce the
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// next 8 octets of ciphertext. These are loaded into FR and the
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// process is repeated until the plaintext is used up.
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for (i = 0; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt((n - 2) +
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i));
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}
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} else {
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plaintext = " " + plaintext;
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// 9. FRE is xored with the first 8 octets of the given plaintext, now
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// that we have finished encrypting the 10 octets of prefixed data.
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// This produces C11-C18, the next 8 octets of ciphertext.
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for (i = 2; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(i));
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var tempCiphertext = ciphertext.substring(0, 2 * block_size).split('');
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var tempCiphertextString = ciphertext.substring(block_size);
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for (n = block_size; n < plaintext.length; n += block_size) {
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// 10. FR is loaded with C11-C18
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for (i = 0; i < block_size; i++) FR[i] = tempCiphertextString.charCodeAt(i);
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tempCiphertextString = '';
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// 11. FR is encrypted to produce FRE.
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FRE = cipherfn.encrypt(FR);
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// 12. FRE is xored with the next 8 octets of plaintext, to produce the
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// next 8 octets of ciphertext. These are loaded into FR and the
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// process is repeated until the plaintext is used up.
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for (i = 0; i < block_size; i++) {
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tempCiphertext.push(String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n + i)));
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tempCiphertextString += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n + i));
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}
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}
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ciphertext = tempCiphertext.join('');
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}
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ciphertext = ciphertext.substring(0, plaintext.length + 2 + block_size);
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return ciphertext;
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},
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/**
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* Decrypts the prefixed data for the Modification Detection Code (MDC) computation
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* @param {String} cipherfn.encrypt Cipher function to use,
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* @see module:crypto/cipher.
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* @param {String} key binary string representation of key to be used to check the mdc
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* This will be passed to the cipherfn
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* @param {String} ciphertext The encrypted data
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* @return {String} plaintext Data of D(ciphertext) with blocksize length +2
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*/
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mdc: function(cipherfn, key, ciphertext) {
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cipherfn = new cipher[cipherfn](key);
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var block_size = cipherfn.blockSize;
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var iblock = new Array(block_size);
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var ablock = new Array(block_size);
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var i;
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// initialisation vector
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for (i = 0; i < block_size; i++) iblock[i] = 0;
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iblock = cipherfn.encrypt(iblock);
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for (i = 0; i < block_size; i++) {
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ablock[i] = ciphertext.charCodeAt(i);
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iblock[i] ^= ablock[i];
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}
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ablock = cipherfn.encrypt(ablock);
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return util.bin2str(iblock) +
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String.fromCharCode(ablock[0] ^ ciphertext.charCodeAt(block_size)) +
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String.fromCharCode(ablock[1] ^ ciphertext.charCodeAt(block_size + 1));
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},
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/**
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* This function decrypts a given plaintext using the specified
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* blockcipher to decrypt a message
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* @param {String} cipherfn the algorithm cipher class to decrypt
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* data in one block_size encryption, @see module:crypto/cipher.
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* @param {String} key binary string representation of key to be used to decrypt the ciphertext.
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* This will be passed to the cipherfn
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* @param {String} ciphertext to be decrypted provided as a string
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* @param {Boolean} resync a boolean value specifying if a resync of the
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* IV should be used or not. The encrypteddatapacket uses the
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* "old" style with a resync. Decryption within an
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* encryptedintegrityprotecteddata packet is not resyncing the IV.
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* @return {String} a string with the plaintext data
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*/
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decrypt: function(cipherfn, key, ciphertext, resync) {
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cipherfn = new cipher[cipherfn](key);
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var block_size = cipherfn.blockSize;
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var iblock = new Array(block_size);
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var ablock = new Array(block_size);
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var i, n = '';
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var text = [];
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// initialisation vector
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for (i = 0; i < block_size; i++) iblock[i] = 0;
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iblock = cipherfn.encrypt(iblock, key);
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for (i = 0; i < block_size; i++) {
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ablock[i] = ciphertext.charCodeAt(i);
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iblock[i] ^= ablock[i];
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}
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ablock = cipherfn.encrypt(ablock, key);
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// test check octets
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if (iblock[block_size - 2] != (ablock[0] ^ ciphertext.charCodeAt(block_size)) || iblock[block_size - 1] != (ablock[
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1] ^ ciphertext.charCodeAt(block_size + 1))) {
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throw new Error('Invalid data.');
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}
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/* RFC4880: Tag 18 and Resync:
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* [...] Unlike the Symmetrically Encrypted Data Packet, no
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* special CFB resynchronization is done after encrypting this prefix
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* data. See "OpenPGP CFB Mode" below for more details.
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*/
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if (resync) {
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for (i = 0; i < block_size; i++) iblock[i] = ciphertext.charCodeAt(i + 2);
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for (n = block_size + 2; n < ciphertext.length; n += block_size) {
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ablock = cipherfn.encrypt(iblock);
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for (i = 0; i < block_size && i + n < ciphertext.length; i++) {
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iblock[i] = ciphertext.charCodeAt(n + i);
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text.push(String.fromCharCode(ablock[i] ^ iblock[i]));
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}
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}
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} else {
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for (i = 0; i < block_size; i++) iblock[i] = ciphertext.charCodeAt(i);
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for (n = block_size; n < ciphertext.length; n += block_size) {
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ablock = cipherfn.encrypt(iblock);
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for (i = 0; i < block_size && i + n < ciphertext.length; i++) {
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iblock[i] = ciphertext.charCodeAt(n + i);
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text.push(String.fromCharCode(ablock[i] ^ iblock[i]));
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}
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}
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}
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n = resync ? 0 : 2;
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text = text.join('');
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text = text.substring(n, ciphertext.length - block_size - 2 + n);
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return text;
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},
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normalEncrypt: function(cipherfn, key, plaintext, iv) {
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cipherfn = new cipher[cipherfn](key);
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var block_size = cipherfn.blockSize;
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var blocki = "";
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var blockc = "";
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var pos = 0;
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var cyphertext = [];
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var tempBlock = [];
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blockc = iv.substring(0, block_size);
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while (plaintext.length > block_size * pos) {
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var encblock = cipherfn.encrypt(util.str2bin(blockc));
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blocki = plaintext.substring((pos * block_size), (pos * block_size) + block_size);
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for (var i = 0; i < blocki.length; i++)
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tempBlock.push(String.fromCharCode(blocki.charCodeAt(i) ^ encblock[i]));
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blockc = tempBlock.join('');
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tempBlock = [];
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cyphertext.push(blockc);
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pos++;
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}
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return cyphertext.join('');
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},
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normalDecrypt: function(cipherfn, key, ciphertext, iv) {
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cipherfn = new cipher[cipherfn](key);
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var block_size = cipherfn.blockSize;
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var blockp = "";
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var pos = 0;
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var plaintext = [];
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var offset = 0;
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var i;
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if (iv === null)
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for (i = 0; i < block_size; i++) blockp += String.fromCharCode(0);
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else
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blockp = iv.substring(0, block_size);
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while (ciphertext.length > (block_size * pos)) {
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var decblock = cipherfn.encrypt(util.str2bin(blockp));
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blockp = ciphertext.substring((pos * (block_size)) + offset, (pos * (block_size)) + (block_size) + offset);
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for (i = 0; i < blockp.length; i++) {
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plaintext.push(String.fromCharCode(blockp.charCodeAt(i) ^ decblock[i]));
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}
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pos++;
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}
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return plaintext.join('');
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}
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};
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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 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