Edit File: cipher.js
/** * Cipher base API. * * @author Dave Longley * * Copyright (c) 2010-2014 Digital Bazaar, Inc. */ var forge = require('./forge'); require('./util'); module.exports = forge.cipher = forge.cipher || {}; // registered algorithms forge.cipher.algorithms = forge.cipher.algorithms || {}; /** * Creates a cipher object that can be used to encrypt data using the given * algorithm and key. The algorithm may be provided as a string value for a * previously registered algorithm or it may be given as a cipher algorithm * API object. * * @param algorithm the algorithm to use, either a string or an algorithm API * object. * @param key the key to use, as a binary-encoded string of bytes or a * byte buffer. * * @return the cipher. */ forge.cipher.createCipher = function(algorithm, key) { var api = algorithm; if(typeof api === 'string') { api = forge.cipher.getAlgorithm(api); if(api) { api = api(); } } if(!api) { throw new Error('Unsupported algorithm: ' + algorithm); } // assume block cipher return new forge.cipher.BlockCipher({ algorithm: api, key: key, decrypt: false }); }; /** * Creates a decipher object that can be used to decrypt data using the given * algorithm and key. The algorithm may be provided as a string value for a * previously registered algorithm or it may be given as a cipher algorithm * API object. * * @param algorithm the algorithm to use, either a string or an algorithm API * object. * @param key the key to use, as a binary-encoded string of bytes or a * byte buffer. * * @return the cipher. */ forge.cipher.createDecipher = function(algorithm, key) { var api = algorithm; if(typeof api === 'string') { api = forge.cipher.getAlgorithm(api); if(api) { api = api(); } } if(!api) { throw new Error('Unsupported algorithm: ' + algorithm); } // assume block cipher return new forge.cipher.BlockCipher({ algorithm: api, key: key, decrypt: true }); }; /** * Registers an algorithm by name. If the name was already registered, the * algorithm API object will be overwritten. * * @param name the name of the algorithm. * @param algorithm the algorithm API object. */ forge.cipher.registerAlgorithm = function(name, algorithm) { name = name.toUpperCase(); forge.cipher.algorithms[name] = algorithm; }; /** * Gets a registered algorithm by name. * * @param name the name of the algorithm. * * @return the algorithm, if found, null if not. */ forge.cipher.getAlgorithm = function(name) { name = name.toUpperCase(); if(name in forge.cipher.algorithms) { return forge.cipher.algorithms[name]; } return null; }; var BlockCipher = forge.cipher.BlockCipher = function(options) { this.algorithm = options.algorithm; this.mode = this.algorithm.mode; this.blockSize = this.mode.blockSize; this._finish = false; this._input = null; this.output = null; this._op = options.decrypt ? this.mode.decrypt : this.mode.encrypt; this._decrypt = options.decrypt; this.algorithm.initialize(options); }; /** * Starts or restarts the encryption or decryption process, whichever * was previously configured. * * For non-GCM mode, the IV may be a binary-encoded string of bytes, an array * of bytes, a byte buffer, or an array of 32-bit integers. If the IV is in * bytes, then it must be Nb (16) bytes in length. If the IV is given in as * 32-bit integers, then it must be 4 integers long. * * Note: an IV is not required or used in ECB mode. * * For GCM-mode, the IV must be given as a binary-encoded string of bytes or * a byte buffer. The number of bytes should be 12 (96 bits) as recommended * by NIST SP-800-38D but another length may be given. * * @param options the options to use: * iv the initialization vector to use as a binary-encoded string of * bytes, null to reuse the last ciphered block from a previous * update() (this "residue" method is for legacy support only). * additionalData additional authentication data as a binary-encoded * string of bytes, for 'GCM' mode, (default: none). * tagLength desired length of authentication tag, in bits, for * 'GCM' mode (0-128, default: 128). * tag the authentication tag to check if decrypting, as a * binary-encoded string of bytes. * output the output the buffer to write to, null to create one. */ BlockCipher.prototype.start = function(options) { options = options || {}; var opts = {}; for(var key in options) { opts[key] = options[key]; } opts.decrypt = this._decrypt; this._finish = false; this._input = forge.util.createBuffer(); this.output = options.output || forge.util.createBuffer(); this.mode.start(opts); }; /** * Updates the next block according to the cipher mode. * * @param input the buffer to read from. */ BlockCipher.prototype.update = function(input) { if(input) { // input given, so empty it into the input buffer this._input.putBuffer(input); } // do cipher operation until it needs more input and not finished while(!this._op.call(this.mode, this._input, this.output, this._finish) && !this._finish) {} // free consumed memory from input buffer this._input.compact(); }; /** * Finishes encrypting or decrypting. * * @param pad a padding function to use in CBC mode, null for default, * signature(blockSize, buffer, decrypt). * * @return true if successful, false on error. */ BlockCipher.prototype.finish = function(pad) { // backwards-compatibility w/deprecated padding API // Note: will overwrite padding functions even after another start() call if(pad && (this.mode.name === 'ECB' || this.mode.name === 'CBC')) { this.mode.pad = function(input) { return pad(this.blockSize, input, false); }; this.mode.unpad = function(output) { return pad(this.blockSize, output, true); }; } // build options for padding and afterFinish functions var options = {}; options.decrypt = this._decrypt; // get # of bytes that won't fill a block options.overflow = this._input.length() % this.blockSize; if(!this._decrypt && this.mode.pad) { if(!this.mode.pad(this._input, options)) { return false; } } // do final update this._finish = true; this.update(); if(this._decrypt && this.mode.unpad) { if(!this.mode.unpad(this.output, options)) { return false; } } if(this.mode.afterFinish) { if(!this.mode.afterFinish(this.output, options)) { return false; } } return true; };
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