Adding float-no-zero branch hosted build

float-no-zero/closure-library/closure/goog/crypt/cbc.js

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+// Copyright 2012 The Closure Library Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS-IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/**
+ * @fileoverview Implementation of CBC mode for block ciphers.  See
+ *     http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation
+ *     #Cipher-block_chaining_.28CBC.29. for description.
+ *
+ * @author nnaze@google.com (Nathan Naze)
+ */
+
+goog.provide('goog.crypt.Cbc');
+
+goog.require('goog.array');
+goog.require('goog.crypt');
+
+
+
+/**
+ * Implements the CBC mode for block ciphers. See
+ * http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation
+ * #Cipher-block_chaining_.28CBC.29
+ *
+ * @param {!goog.crypt.BlockCipher} cipher The block cipher to use.
+ * @param {number=} opt_blockSize The block size of the cipher in bytes.
+ *     Defaults to 16 bytes.
+ * @constructor
+ */
+goog.crypt.Cbc = function(cipher, opt_blockSize) {
+
+  /**
+   * Block cipher.
+   * @type {!goog.crypt.BlockCipher}
+   * @private
+   */
+  this.cipher_ = cipher;
+
+  /**
+   * Block size in bytes.
+   * @type {number}
+   * @private
+   */
+  this.blockSize_ = opt_blockSize || 16;
+};
+
+
+/**
+ * Encrypt a message.
+ *
+ * @param {!Array.<number>} plainText Message to encrypt. An array of bytes.
+ *     The length should be a multiple of the block size.
+ * @param {!Array.<number>} initialVector Initial vector for the CBC mode.
+ *     An array of bytes with the same length as the block size.
+ * @return {!Array.<number>} Encrypted message.
+ */
+goog.crypt.Cbc.prototype.encrypt = function(plainText, initialVector) {
+
+  goog.asserts.assert(
+      plainText.length % this.blockSize_ == 0,
+      'Data\'s length must be multiple of block size.');
+
+  goog.asserts.assert(
+      initialVector.length == this.blockSize_,
+      'Initial vector must be size of one block.');
+
+  // Implementation of
+  // http://en.wikipedia.org/wiki/File:Cbc_encryption.png
+
+  var cipherText = [];
+  var vector = initialVector;
+
+  // Generate each block of the encrypted cypher text.
+  for (var blockStartIndex = 0;
+       blockStartIndex < plainText.length;
+       blockStartIndex += this.blockSize_) {
+
+    // Takes one block from the input message.
+    var plainTextBlock = goog.array.slice(
+        plainText,
+        blockStartIndex,
+        blockStartIndex + this.blockSize_);
+
+    var input = goog.crypt.xorByteArray(plainTextBlock, vector);
+    var resultBlock = this.cipher_.encrypt(input);
+
+    goog.array.extend(cipherText, resultBlock);
+    vector = resultBlock;
+  }
+
+  return cipherText;
+};
+
+
+/**
+ * Decrypt a message.
+ *
+ * @param {!Array.<number>} cipherText Message to decrypt. An array of bytes.
+ *     The length should be a multiple of the block size.
+ * @param {!Array.<number>} initialVector Initial vector for the CBC mode.
+ *     An array of bytes with the same length as the block size.
+ * @return {!Array.<number>} Decrypted message.
+ */
+goog.crypt.Cbc.prototype.decrypt = function(cipherText, initialVector) {
+
+  goog.asserts.assert(
+      cipherText.length % this.blockSize_ == 0,
+      'Data\'s length must be multiple of block size.');
+
+  goog.asserts.assert(
+      initialVector.length == this.blockSize_,
+      'Initial vector must be size of one block.');
+
+  // Implementation of
+  // http://en.wikipedia.org/wiki/File:Cbc_decryption.png
+
+  var plainText = [];
+  var blockStartIndex = 0;
+  var vector = initialVector;
+
+  // Generate each block of the decrypted plain text.
+  while (blockStartIndex < cipherText.length) {
+
+    // Takes one block.
+    var cipherTextBlock = goog.array.slice(
+        cipherText,
+        blockStartIndex,
+        blockStartIndex + this.blockSize_);
+
+    var resultBlock = this.cipher_.decrypt(cipherTextBlock);
+    var plainTextBlock = goog.crypt.xorByteArray(vector, resultBlock);
+
+    goog.array.extend(plainText, plainTextBlock);
+    vector = cipherTextBlock;
+
+    blockStartIndex += this.blockSize_;
+  }
+
+  return plainText;
+};