// Copyright 2011 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 MD5 cryptographic hash.
 * Implementation of http://tools.ietf.org/html/rfc1321 with common
 * optimizations and tweaks (see http://en.wikipedia.org/wiki/MD5).
 *
 * Usage:
 *   var md5 = new goog.crypt.Md5();
 *   md5.update(bytes);
 *   var hash = md5.digest();
 *
 * Performance:
 *   Chrome 23              ~680 Mbit/s
 *   Chrome 13 (in a VM)    ~250 Mbit/s
 *   Firefox 6.0 (in a VM)  ~100 Mbit/s
 *   IE9 (in a VM)           ~27 Mbit/s
 *   Firefox 3.6             ~15 Mbit/s
 *   IE8 (in a VM)           ~13 Mbit/s
 *
 */

goog.provide('goog.crypt.Md5');

goog.require('goog.crypt.Hash');



/**
 * MD5 cryptographic hash constructor.
 * @constructor
 * @extends {goog.crypt.Hash}
 * @final
 * @struct
 */
goog.crypt.Md5 = function() {
  goog.crypt.Md5.base(this, 'constructor');

  this.blockSize = 512 / 8;

  /**
   * Holds the current values of accumulated A-D variables (MD buffer).
   * @type {!Array<number>}
   * @private
   */
  this.chain_ = new Array(4);

  /**
   * A buffer holding the data until the whole block can be processed.
   * @type {!Array<number>}
   * @private
   */
  this.block_ = new Array(this.blockSize);

  /**
   * The length of yet-unprocessed data as collected in the block.
   * @type {number}
   * @private
   */
  this.blockLength_ = 0;

  /**
   * The total length of the message so far.
   * @type {number}
   * @private
   */
  this.totalLength_ = 0;

  this.reset();
};
goog.inherits(goog.crypt.Md5, goog.crypt.Hash);


/**
 * Integer rotation constants used by the abbreviated implementation.
 * They are hardcoded in the unrolled implementation, so it is left
 * here commented out.
 * @type {Array<number>}
 * @private
 *
goog.crypt.Md5.S_ = [
  7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
  5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
  4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
  6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21
];
 */

/**
 * Sine function constants used by the abbreviated implementation.
 * They are hardcoded in the unrolled implementation, so it is left
 * here commented out.
 * @type {Array<number>}
 * @private
 *
goog.crypt.Md5.T_ = [
  0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
  0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
  0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
  0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
  0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
  0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
  0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
  0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
  0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
  0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
  0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
  0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
  0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
  0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
  0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
  0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
];
 */


/** @override */
goog.crypt.Md5.prototype.reset = function() {
  this.chain_[0] = 0x67452301;
  this.chain_[1] = 0xefcdab89;
  this.chain_[2] = 0x98badcfe;
  this.chain_[3] = 0x10325476;

  this.blockLength_ = 0;
  this.totalLength_ = 0;
};


/**
 * Internal compress helper function. It takes a block of data (64 bytes)
 * and updates the accumulator.
 * @param {Array<number>|Uint8Array|string} buf The block to compress.
 * @param {number=} opt_offset Offset of the block in the buffer.
 * @private
 */
goog.crypt.Md5.prototype.compress_ = function(buf, opt_offset) {
  if (!opt_offset) {
    opt_offset = 0;
  }

  // We allocate the array every time, but it's cheap in practice.
  var X = new Array(16);

  // Get 16 little endian words. It is not worth unrolling this for Chrome 11.
  if (goog.isString(buf)) {
    for (var i = 0; i < 16; ++i) {
      X[i] = (buf.charCodeAt(opt_offset++)) |
             (buf.charCodeAt(opt_offset++) << 8) |
             (buf.charCodeAt(opt_offset++) << 16) |
             (buf.charCodeAt(opt_offset++) << 24);
    }
  } else {
    for (var i = 0; i < 16; ++i) {
      X[i] = (buf[opt_offset++]) |
             (buf[opt_offset++] << 8) |
             (buf[opt_offset++] << 16) |
             (buf[opt_offset++] << 24);
    }
  }

  var A = this.chain_[0];
  var B = this.chain_[1];
  var C = this.chain_[2];
  var D = this.chain_[3];
  var sum = 0;

  /*
   * This is an abbreviated implementation, it is left here commented out for
   * reference purposes. See below for an unrolled version in use.
   *
  var f, n, tmp;
  for (var i = 0; i < 64; ++i) {

    if (i < 16) {
      f = (D ^ (B & (C ^ D)));
      n = i;
    } else if (i < 32) {
      f = (C ^ (D & (B ^ C)));
      n = (5 * i + 1) % 16;
    } else if (i < 48) {
      f = (B ^ C ^ D);
      n = (3 * i + 5) % 16;
    } else {
      f = (C ^ (B | (~D)));
      n = (7 * i) % 16;
    }

    tmp = D;
    D = C;
    C = B;
    sum = (A + f + goog.crypt.Md5.T_[i] + X[n]) & 0xffffffff;
    B += ((sum << goog.crypt.Md5.S_[i]) & 0xffffffff) |
         (sum >>> (32 - goog.crypt.Md5.S_[i]));
    A = tmp;
  }
   */

  /*
   * This is an unrolled MD5 implementation, which gives ~30% speedup compared
   * to the abbreviated implementation above, as measured on Chrome 11. It is
   * important to keep 32-bit croppings to minimum and inline the integer
   * rotation.
   */
  sum = (A + (D ^ (B & (C ^ D))) + X[0] + 0xd76aa478) & 0xffffffff;
  A = B + (((sum << 7) & 0xffffffff) | (sum >>> 25));
  sum = (D + (C ^ (A & (B ^ C))) + X[1] + 0xe8c7b756) & 0xffffffff;
  D = A + (((sum << 12) & 0xffffffff) | (sum >>> 20));
  sum = (C + (B ^ (D & (A ^ B))) + X[2] + 0x242070db) & 0xffffffff;
  C = D + (((sum << 17) & 0xffffffff) | (sum >>> 15));
  sum = (B + (A ^ (C & (D ^ A))) + X[3] + 0xc1bdceee) & 0xffffffff;
  B = C + (((sum << 22) & 0xffffffff) | (sum >>> 10));
  sum = (A + (D ^ (B & (C ^ D))) + X[4] + 0xf57c0faf) & 0xffffffff;
  A = B + (((sum << 7) & 0xffffffff) | (sum >>> 25));
  sum = (D + (C ^ (A & (B ^ C))) + X[5] + 0x4787c62a) & 0xffffffff;
  D = A + (((sum << 12) & 0xffffffff) | (sum >>> 20));
  sum = (C + (B ^ (D & (A ^ B))) + X[6] + 0xa8304613) & 0xffffffff;
  C = D + (((sum << 17) & 0xffffffff) | (sum >>> 15));
  sum = (B + (A ^ (C & (D ^ A))) + X[7] + 0xfd469501) & 0xffffffff;
  B = C + (((sum << 22) & 0xffffffff) | (sum >>> 10));
  sum = (A + (D ^ (B & (C ^ D))) + X[8] + 0x698098d8) & 0xffffffff;
  A = B + (((sum << 7) & 0xffffffff) | (sum >>> 25));
  sum = (D + (C ^ (A & (B ^ C))) + X[9] + 0x8b44f7af) & 0xffffffff;
  D = A + (((sum << 12) & 0xffffffff) | (sum >>> 20));
  sum = (C + (B ^ (D & (A ^ B))) + X[10] + 0xffff5bb1) & 0xffffffff;
  C = D + (((sum << 17) & 0xffffffff) | (sum >>> 15));
  sum = (B + (A ^ (C & (D ^ A))) + X[11] + 0x895cd7be) & 0xffffffff;
  B = C + (((sum << 22) & 0xffffffff) | (sum >>> 10));
  sum = (A + (D ^ (B & (C ^ D))) + X[12] + 0x6b901122) & 0xffffffff;
  A = B + (((sum << 7) & 0xffffffff) | (sum >>> 25));
  sum = (D + (C ^ (A & (B ^ C))) + X[13] + 0xfd987193) & 0xffffffff;
  D = A + (((sum << 12) & 0xffffffff) | (sum >>> 20));
  sum = (C + (B ^ (D & (A ^ B))) + X[14] + 0xa679438e) & 0xffffffff;
  C = D + (((sum << 17) & 0xffffffff) | (sum >>> 15));
  sum = (B + (A ^ (C & (D ^ A))) + X[15] + 0x49b40821) & 0xffffffff;
  B = C + (((sum << 22) & 0xffffffff) | (sum >>> 10));
  sum = (A + (C ^ (D & (B ^ C))) + X[1] + 0xf61e2562) & 0xffffffff;
  A = B + (((sum << 5) & 0xffffffff) | (sum >>> 27));
  sum = (D + (B ^ (C & (A ^ B))) + X[6] + 0xc040b340) & 0xffffffff;
  D = A + (((sum << 9) & 0xffffffff) | (sum >>> 23));
  sum = (C + (A ^ (B & (D ^ A))) + X[11] + 0x265e5a51) & 0xffffffff;
  C = D + (((sum << 14) & 0xffffffff) | (sum >>> 18));
  sum = (B + (D ^ (A & (C ^ D))) + X[0] + 0xe9b6c7aa) & 0xffffffff;
  B = C + (((sum << 20) & 0xffffffff) | (sum >>> 12));
  sum = (A + (C ^ (D & (B ^ C))) + X[5] + 0xd62f105d) & 0xffffffff;
  A = B + (((sum << 5) & 0xffffffff) | (sum >>> 27));
  sum = (D + (B ^ (C & (A ^ B))) + X[10] + 0x02441453) & 0xffffffff;
  D = A + (((sum << 9) & 0xffffffff) | (sum >>> 23));
  sum = (C + (A ^ (B & (D ^ A))) + X[15] + 0xd8a1e681) & 0xffffffff;
  C = D + (((sum << 14) & 0xffffffff) | (sum >>> 18));
  sum = (B + (D ^ (A & (C ^ D))) + X[4] + 0xe7d3fbc8) & 0xffffffff;
  B = C + (((sum << 20) & 0xffffffff) | (sum >>> 12));
  sum = (A + (C ^ (D & (B ^ C))) + X[9] + 0x21e1cde6) & 0xffffffff;
  A = B + (((sum << 5) & 0xffffffff) | (sum >>> 27));
  sum = (D + (B ^ (C & (A ^ B))) + X[14] + 0xc33707d6) & 0xffffffff;
  D = A + (((sum << 9) & 0xffffffff) | (sum >>> 23));
  sum = (C + (A ^ (B & (D ^ A))) + X[3] + 0xf4d50d87) & 0xffffffff;
  C = D + (((sum << 14) & 0xffffffff) | (sum >>> 18));
  sum = (B + (D ^ (A & (C ^ D))) + X[8] + 0x455a14ed) & 0xffffffff;
  B = C + (((sum << 20) & 0xffffffff) | (sum >>> 12));
  sum = (A + (C ^ (D & (B ^ C))) + X[13] + 0xa9e3e905) & 0xffffffff;
  A = B + (((sum << 5) & 0xffffffff) | (sum >>> 27));
  sum = (D + (B ^ (C & (A ^ B))) + X[2] + 0xfcefa3f8) & 0xffffffff;
  D = A + (((sum << 9) & 0xffffffff) | (sum >>> 23));
  sum = (C + (A ^ (B & (D ^ A))) + X[7] + 0x676f02d9) & 0xffffffff;
  C = D + (((sum << 14) & 0xffffffff) | (sum >>> 18));
  sum = (B + (D ^ (A & (C ^ D))) + X[12] + 0x8d2a4c8a) & 0xffffffff;
  B = C + (((sum << 20) & 0xffffffff) | (sum >>> 12));
  sum = (A + (B ^ C ^ D) + X[5] + 0xfffa3942) & 0xffffffff;
  A = B + (((sum << 4) & 0xffffffff) | (sum >>> 28));
  sum = (D + (A ^ B ^ C) + X[8] + 0x8771f681) & 0xffffffff;
  D = A + (((sum << 11) & 0xffffffff) | (sum >>> 21));
  sum = (C + (D ^ A ^ B) + X[11] + 0x6d9d6122) & 0xffffffff;
  C = D + (((sum << 16) & 0xffffffff) | (sum >>> 16));
  sum = (B + (C ^ D ^ A) + X[14] + 0xfde5380c) & 0xffffffff;
  B = C + (((sum << 23) & 0xffffffff) | (sum >>> 9));
  sum = (A + (B ^ C ^ D) + X[1] + 0xa4beea44) & 0xffffffff;
  A = B + (((sum << 4) & 0xffffffff) | (sum >>> 28));
  sum = (D + (A ^ B ^ C) + X[4] + 0x4bdecfa9) & 0xffffffff;
  D = A + (((sum << 11) & 0xffffffff) | (sum >>> 21));
  sum = (C + (D ^ A ^ B) + X[7] + 0xf6bb4b60) & 0xffffffff;
  C = D + (((sum << 16) & 0xffffffff) | (sum >>> 16));
  sum = (B + (C ^ D ^ A) + X[10] + 0xbebfbc70) & 0xffffffff;
  B = C + (((sum << 23) & 0xffffffff) | (sum >>> 9));
  sum = (A + (B ^ C ^ D) + X[13] + 0x289b7ec6) & 0xffffffff;
  A = B + (((sum << 4) & 0xffffffff) | (sum >>> 28));
  sum = (D + (A ^ B ^ C) + X[0] + 0xeaa127fa) & 0xffffffff;
  D = A + (((sum << 11) & 0xffffffff) | (sum >>> 21));
  sum = (C + (D ^ A ^ B) + X[3] + 0xd4ef3085) & 0xffffffff;
  C = D + (((sum << 16) & 0xffffffff) | (sum >>> 16));
  sum = (B + (C ^ D ^ A) + X[6] + 0x04881d05) & 0xffffffff;
  B = C + (((sum << 23) & 0xffffffff) | (sum >>> 9));
  sum = (A + (B ^ C ^ D) + X[9] + 0xd9d4d039) & 0xffffffff;
  A = B + (((sum << 4) & 0xffffffff) | (sum >>> 28));
  sum = (D + (A ^ B ^ C) + X[12] + 0xe6db99e5) & 0xffffffff;
  D = A + (((sum << 11) & 0xffffffff) | (sum >>> 21));
  sum = (C + (D ^ A ^ B) + X[15] + 0x1fa27cf8) & 0xffffffff;
  C = D + (((sum << 16) & 0xffffffff) | (sum >>> 16));
  sum = (B + (C ^ D ^ A) + X[2] + 0xc4ac5665) & 0xffffffff;
  B = C + (((sum << 23) & 0xffffffff) | (sum >>> 9));
  sum = (A + (C ^ (B | (~D))) + X[0] + 0xf4292244) & 0xffffffff;
  A = B + (((sum << 6) & 0xffffffff) | (sum >>> 26));
  sum = (D + (B ^ (A | (~C))) + X[7] + 0x432aff97) & 0xffffffff;
  D = A + (((sum << 10) & 0xffffffff) | (sum >>> 22));
  sum = (C + (A ^ (D | (~B))) + X[14] + 0xab9423a7) & 0xffffffff;
  C = D + (((sum << 15) & 0xffffffff) | (sum >>> 17));
  sum = (B + (D ^ (C | (~A))) + X[5] + 0xfc93a039) & 0xffffffff;
  B = C + (((sum << 21) & 0xffffffff) | (sum >>> 11));
  sum = (A + (C ^ (B | (~D))) + X[12] + 0x655b59c3) & 0xffffffff;
  A = B + (((sum << 6) & 0xffffffff) | (sum >>> 26));
  sum = (D + (B ^ (A | (~C))) + X[3] + 0x8f0ccc92) & 0xffffffff;
  D = A + (((sum << 10) & 0xffffffff) | (sum >>> 22));
  sum = (C + (A ^ (D | (~B))) + X[10] + 0xffeff47d) & 0xffffffff;
  C = D + (((sum << 15) & 0xffffffff) | (sum >>> 17));
  sum = (B + (D ^ (C | (~A))) + X[1] + 0x85845dd1) & 0xffffffff;
  B = C + (((sum << 21) & 0xffffffff) | (sum >>> 11));
  sum = (A + (C ^ (B | (~D))) + X[8] + 0x6fa87e4f) & 0xffffffff;
  A = B + (((sum << 6) & 0xffffffff) | (sum >>> 26));
  sum = (D + (B ^ (A | (~C))) + X[15] + 0xfe2ce6e0) & 0xffffffff;
  D = A + (((sum << 10) & 0xffffffff) | (sum >>> 22));
  sum = (C + (A ^ (D | (~B))) + X[6] + 0xa3014314) & 0xffffffff;
  C = D + (((sum << 15) & 0xffffffff) | (sum >>> 17));
  sum = (B + (D ^ (C | (~A))) + X[13] + 0x4e0811a1) & 0xffffffff;
  B = C + (((sum << 21) & 0xffffffff) | (sum >>> 11));
  sum = (A + (C ^ (B | (~D))) + X[4] + 0xf7537e82) & 0xffffffff;
  A = B + (((sum << 6) & 0xffffffff) | (sum >>> 26));
  sum = (D + (B ^ (A | (~C))) + X[11] + 0xbd3af235) & 0xffffffff;
  D = A + (((sum << 10) & 0xffffffff) | (sum >>> 22));
  sum = (C + (A ^ (D | (~B))) + X[2] + 0x2ad7d2bb) & 0xffffffff;
  C = D + (((sum << 15) & 0xffffffff) | (sum >>> 17));
  sum = (B + (D ^ (C | (~A))) + X[9] + 0xeb86d391) & 0xffffffff;
  B = C + (((sum << 21) & 0xffffffff) | (sum >>> 11));

  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;
};


/** @override */
goog.crypt.Md5.prototype.update = function(bytes, opt_length) {
  if (!goog.isDef(opt_length)) {
    opt_length = bytes.length;
  }
  var lengthMinusBlock = opt_length - this.blockSize;

  // Copy some object properties to local variables in order to save on access
  // time from inside the loop (~10% speedup was observed on Chrome 11).
  var block = this.block_;
  var blockLength = this.blockLength_;
  var i = 0;

  // The outer while loop should execute at most twice.
  while (i < opt_length) {
    // When we have no data in the block to top up, we can directly process the
    // input buffer (assuming it contains sufficient data). This gives ~30%
    // speedup on Chrome 14 and ~70% speedup on Firefox 6.0, but requires that
    // the data is provided in large chunks (or in multiples of 64 bytes).
    if (blockLength == 0) {
      while (i <= lengthMinusBlock) {
        this.compress_(bytes, i);
        i += this.blockSize;
      }
    }

    if (goog.isString(bytes)) {
      while (i < opt_length) {
        block[blockLength++] = bytes.charCodeAt(i++);
        if (blockLength == this.blockSize) {
          this.compress_(block);
          blockLength = 0;
          // Jump to the outer loop so we use the full-block optimization.
          break;
        }
      }
    } else {
      while (i < opt_length) {
        block[blockLength++] = bytes[i++];
        if (blockLength == this.blockSize) {
          this.compress_(block);
          blockLength = 0;
          // Jump to the outer loop so we use the full-block optimization.
          break;
        }
      }
    }
  }

  this.blockLength_ = blockLength;
  this.totalLength_ += opt_length;
};


/** @override */
goog.crypt.Md5.prototype.digest = function() {
  // This must accommodate at least 1 padding byte (0x80), 8 bytes of
  // total bitlength, and must end at a 64-byte boundary.
  var pad = new Array((this.blockLength_ < 56 ?
                       this.blockSize :
                       this.blockSize * 2) - this.blockLength_);

  // Add padding: 0x80 0x00*
  pad[0] = 0x80;
  for (var i = 1; i < pad.length - 8; ++i) {
    pad[i] = 0;
  }
  // Add the total number of bits, little endian 64-bit integer.
  var totalBits = this.totalLength_ * 8;
  for (var i = pad.length - 8; i < pad.length; ++i) {
    pad[i] = totalBits & 0xff;
    totalBits /= 0x100; // Don't use bit-shifting here!
  }
  this.update(pad);

  var digest = new Array(16);
  var n = 0;
  for (var i = 0; i < 4; ++i) {
    for (var j = 0; j < 32; j += 8) {
      digest[n++] = (this.chain_[i] >>> j) & 0xff;
    }
  }
  return digest;
};
