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master/closure-library/closure/goog/crypt/sha1.js

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+// Copyright 2005 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 SHA-1 cryptographic hash.
+ * Variable names follow the notation in FIPS PUB 180-3:
+ * http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf.
+ *
+ * Usage:
+ *   var sha1 = new goog.crypt.sha1();
+ *   sha1.update(bytes);
+ *   var hash = sha1.digest();
+ *
+ */
+
+goog.provide('goog.crypt.Sha1');
+
+goog.require('goog.crypt.Hash');
+
+
+
+/**
+ * SHA-1 cryptographic hash constructor.
+ *
+ * The properties declared here are discussed in the above algorithm document.
+ * @constructor
+ * @extends {goog.crypt.Hash}
+ */
+goog.crypt.Sha1 = function() {
+  goog.base(this);
+
+  /**
+   * Holds the previous values of accumulated variables a-e in the compress_
+   * function.
+   * @type {Array.<number>}
+   * @private
+   */
+  this.chain_ = [];
+
+  /**
+   * A buffer holding the partially computed hash result.
+   * @type {Array.<number>}
+   * @private
+   */
+  this.buf_ = [];
+
+  /**
+   * An array of 80 bytes, each a part of the message to be hashed.  Referred to
+   * as the message schedule in the docs.
+   * @type {Array.<number>}
+   * @private
+   */
+  this.W_ = [];
+
+  /**
+   * Contains data needed to pad messages less than 64 bytes.
+   * @type {Array.<number>}
+   * @private
+   */
+  this.pad_ = [];
+
+  this.pad_[0] = 128;
+  for (var i = 1; i < 64; ++i) {
+    this.pad_[i] = 0;
+  }
+
+  this.reset();
+};
+goog.inherits(goog.crypt.Sha1, goog.crypt.Hash);
+
+
+/** @override */
+goog.crypt.Sha1.prototype.reset = function() {
+  this.chain_[0] = 0x67452301;
+  this.chain_[1] = 0xefcdab89;
+  this.chain_[2] = 0x98badcfe;
+  this.chain_[3] = 0x10325476;
+  this.chain_[4] = 0xc3d2e1f0;
+
+  this.inbuf_ = 0;
+  this.total_ = 0;
+};
+
+
+/**
+ * Internal compress helper function.
+ * @param {Array.<number>} buf Buffer with the block to compress.
+ * @param {number=} opt_offset Offset of the block in the buffer.
+ * @private
+ */
+goog.crypt.Sha1.prototype.compress_ = function(buf, opt_offset) {
+  if (!opt_offset) {
+    opt_offset = 0;
+  }
+
+  var W = this.W_;
+
+  // get 16 big endian words
+  for (var i = opt_offset; i < opt_offset + 64; i += 4) {
+    var w = (buf[i] << 24) |
+            (buf[i + 1] << 16) |
+            (buf[i + 2] << 8) |
+            (buf[i + 3]);
+    W[i / 4] = w;
+  }
+
+  // expand to 80 words
+  for (var i = 16; i < 80; i++) {
+    var t = W[i - 3] ^ W[i - 8] ^ W[i - 14] ^ W[i - 16];
+    W[i] = ((t << 1) | (t >>> 31)) & 0xffffffff;
+  }
+
+  var a = this.chain_[0];
+  var b = this.chain_[1];
+  var c = this.chain_[2];
+  var d = this.chain_[3];
+  var e = this.chain_[4];
+  var f, k;
+
+  // TODO(user): Try to unroll this loop to speed up the computation.
+  for (var i = 0; i < 80; i++) {
+    if (i < 40) {
+      if (i < 20) {
+        f = d ^ (b & (c ^ d));
+        k = 0x5a827999;
+      } else {
+        f = b ^ c ^ d;
+        k = 0x6ed9eba1;
+      }
+    } else {
+      if (i < 60) {
+        f = (b & c) | (d & (b | c));
+        k = 0x8f1bbcdc;
+      } else {
+        f = b ^ c ^ d;
+        k = 0xca62c1d6;
+      }
+    }
+
+    var t = (((a << 5) | (a >>> 27)) + f + e + k + W[i]) & 0xffffffff;
+    e = d;
+    d = c;
+    c = ((b << 30) | (b >>> 2)) & 0xffffffff;
+    b = a;
+    a = t;
+  }
+
+  this.chain_[0] = (this.chain_[0] + a) & 0xffffffff;
+  this.chain_[1] = (this.chain_[1] + b) & 0xffffffff;
+  this.chain_[2] = (this.chain_[2] + c) & 0xffffffff;
+  this.chain_[3] = (this.chain_[3] + d) & 0xffffffff;
+  this.chain_[4] = (this.chain_[4] + e) & 0xffffffff;
+};
+
+
+/** @override */
+goog.crypt.Sha1.prototype.update = function(bytes, opt_length) {
+  if (!goog.isDef(opt_length)) {
+    opt_length = bytes.length;
+  }
+
+  var buf = this.buf_;
+  var inbuf = this.inbuf_;
+  var n = 0;
+
+  // Strangely enough, it is faster to copy the data than to pass over the
+  // buffer and an offset. Copying in a loop is also as fast as array slicing.
+  // This was tested on Chrome 11 and Firefox 3.6. Please do not optimize
+  // the following without careful profiling.
+  if (goog.isString(bytes)) {
+    while (n < opt_length) {
+      buf[inbuf++] = bytes.charCodeAt(n++);
+      if (inbuf == 64) {
+        this.compress_(buf);
+        inbuf = 0;
+      }
+    }
+  } else {
+    while (n < opt_length) {
+      buf[inbuf++] = bytes[n++];
+      if (inbuf == 64) {
+        this.compress_(buf);
+        inbuf = 0;
+      }
+    }
+  }
+
+  this.inbuf_ = inbuf;
+  this.total_ += opt_length;
+};
+
+
+/** @override */
+goog.crypt.Sha1.prototype.digest = function() {
+  var digest = [];
+  var totalBits = this.total_ * 8;
+
+  // Add pad 0x80 0x00*.
+  if (this.inbuf_ < 56) {
+    this.update(this.pad_, 56 - this.inbuf_);
+  } else {
+    this.update(this.pad_, 64 - (this.inbuf_ - 56));
+  }
+
+  // Add # bits.
+  for (var i = 63; i >= 56; i--) {
+    this.buf_[i] = totalBits & 255;
+    totalBits /= 256; // Don't use bit-shifting here!
+  }
+
+  this.compress_(this.buf_);
+
+  var n = 0;
+  for (var i = 0; i < 5; i++) {
+    for (var j = 24; j >= 0; j -= 8) {
+      digest[n++] = (this.chain_[i] >> j) & 255;
+    }
+  }
+
+  return digest;
+};