pdf.js/src/core/calculate_md5.js

/* Copyright 2012 Mozilla Foundation
 *
 * 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.
 */

import { shadow } from "../shared/util.js";

const PARAMS = {
  get r() {
    return shadow(
      this,
      "r",
      new Uint8Array([
        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,
      ])
    );
  },

  get k() {
    return shadow(
      this,
      "k",
      new Int32Array([
        -680876936, -389564586, 606105819, -1044525330, -176418897, 1200080426,
        -1473231341, -45705983, 1770035416, -1958414417, -42063, -1990404162,
        1804603682, -40341101, -1502002290, 1236535329, -165796510, -1069501632,
        643717713, -373897302, -701558691, 38016083, -660478335, -405537848,
        568446438, -1019803690, -187363961, 1163531501, -1444681467, -51403784,
        1735328473, -1926607734, -378558, -2022574463, 1839030562, -35309556,
        -1530992060, 1272893353, -155497632, -1094730640, 681279174, -358537222,
        -722521979, 76029189, -640364487, -421815835, 530742520, -995338651,
        -198630844, 1126891415, -1416354905, -57434055, 1700485571, -1894986606,
        -1051523, -2054922799, 1873313359, -30611744, -1560198380, 1309151649,
        -145523070, -1120210379, 718787259, -343485551,
      ])
    );
  },
};

function calculateMD5(data, offset, length) {
  let h0 = 1732584193,
    h1 = -271733879,
    h2 = -1732584194,
    h3 = 271733878;
  // pre-processing
  const paddedLength = (length + 72) & ~63; // data + 9 extra bytes
  const padded = new Uint8Array(paddedLength);
  let i, j;
  for (i = 0; i < length; ++i) {
    padded[i] = data[offset++];
  }
  padded[i++] = 0x80;
  const n = paddedLength - 8;
  if (i < n) {
    i = n;
  }
  padded[i++] = (length << 3) & 0xff;
  padded[i++] = (length >> 5) & 0xff;
  padded[i++] = (length >> 13) & 0xff;
  padded[i++] = (length >> 21) & 0xff;
  padded[i++] = (length >>> 29) & 0xff;
  i += 3;
  const w = new Int32Array(16);
  const { k, r } = PARAMS;
  for (i = 0; i < paddedLength; ) {
    for (j = 0; j < 16; ++j, i += 4) {
      w[j] =
        padded[i] |
        (padded[i + 1] << 8) |
        (padded[i + 2] << 16) |
        (padded[i + 3] << 24);
    }
    let a = h0,
      b = h1,
      c = h2,
      d = h3,
      f,
      g;
    for (j = 0; j < 64; ++j) {
      if (j < 16) {
        f = (b & c) | (~b & d);
        g = j;
      } else if (j < 32) {
        f = (d & b) | (~d & c);
        g = (5 * j + 1) & 15;
      } else if (j < 48) {
        f = b ^ c ^ d;
        g = (3 * j + 5) & 15;
      } else {
        f = c ^ (b | ~d);
        g = (7 * j) & 15;
      }
      const tmp = d,
        rotateArg = (a + f + k[j] + w[g]) | 0,
        rotate = r[j];
      d = c;
      c = b;
      b = (b + ((rotateArg << rotate) | (rotateArg >>> (32 - rotate)))) | 0;
      a = tmp;
    }
    h0 = (h0 + a) | 0;
    h1 = (h1 + b) | 0;
    h2 = (h2 + c) | 0;
    h3 = (h3 + d) | 0;
  }
  // prettier-ignore
  return new Uint8Array([
    h0 & 0xFF, (h0 >> 8) & 0xFF, (h0 >> 16) & 0xFF, (h0 >>> 24) & 0xFF,
    h1 & 0xFF, (h1 >> 8) & 0xFF, (h1 >> 16) & 0xFF, (h1 >>> 24) & 0xFF,
    h2 & 0xFF, (h2 >> 8) & 0xFF, (h2 >> 16) & 0xFF, (h2 >>> 24) & 0xFF,
    h3 & 0xFF, (h3 >> 8) & 0xFF, (h3 >> 16) & 0xFF, (h3 >>> 24) & 0xFF
  ]);
}

export { calculateMD5 };