content: /*******************************************************************************
   * Software Name : RCS IMS Stack
   *
   * Copyright (C) 2010-2016 Orange.
   *
   * 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.
   ******************************************************************************/
  
  package com.gsma.rcs.core.ims.security;
  
  /**
   * implementation of MD5 as outlined in "Handbook of Applied Cryptography", pages 346 - 347.
   */
  public class MD5Digest extends GeneralDigest {
      private static final int DIGEST_LENGTH = 16;
  
      private int H1, H2, H3, H4; // IV's
  
      private int[] X = new int[16];
      private int xOff;
  
      /**
       * Standard constructor
       */
      public MD5Digest() {
          reset();
      }
  
      /**
       * Copy constructor. This will copy the state of the provided message digest.
       */
      public MD5Digest(MD5Digest t) {
          super(t);
  
          H1 = t.H1;
          H2 = t.H2;
          H3 = t.H3;
          H4 = t.H4;
  
          System.arraycopy(t.X, 0, X, 0, t.X.length);
          xOff = t.xOff;
      }
  
      public String getAlgorithmName() {
          return "MD5";
      }
  
      public int getDigestSize() {
          return DIGEST_LENGTH;
      }
  
      protected void processWord(byte[] in, int inOff) {
          X[xOff++] = (in[inOff] & 0xff) | ((in[inOff + 1] & 0xff) << 8)
                  | ((in[inOff + 2] & 0xff) << 16) | ((in[inOff + 3] & 0xff) << 24);
  
          if (xOff == 16) {
              processBlock();
          }
      }
  
      protected void processLength(long bitLength) {
          if (xOff > 14) {
              processBlock();
          }
  
          X[14] = (int) (bitLength & 0xffffffff);
          X[15] = (int) (bitLength >>> 32);
      }
  
      private void unpackWord(int word, byte[] out, int outOff) {
          out[outOff] = (byte) word;
          out[outOff + 1] = (byte) (word >>> 8);
          out[outOff + 2] = (byte) (word >>> 16);
          out[outOff + 3] = (byte) (word >>> 24);
      }
  
      public int doFinal(byte[] out, int outOff) {
          finish();
  
          unpackWord(H1, out, outOff);
          unpackWord(H2, out, outOff + 4);
          unpackWord(H3, out, outOff + 8);
          unpackWord(H4, out, outOff + 12);
  
          reset();
  
          return DIGEST_LENGTH;
      }
  
      /**
       * reset the chaining variables to the IV values.
       */
      public void reset() {
          super.reset();
  
          H1 = 0x67452301;
          H2 = 0xefcdab89;
          H3 = 0x98badcfe;
          H4 = 0x10325476;
  
          xOff = 0;
  
          for (int i = 0; i != X.length; i++) {
              X[i] = 0;
          }
      }
  
      //
      // round 1 left rotates
      //
      private static final int S11 = 7;
      private static final int S12 = 12;
      private static final int S13 = 17;
      private static final int S14 = 22;
  
      //
      // round 2 left rotates
      //
      private static final int S21 = 5;
      private static final int S22 = 9;
      private static final int S23 = 14;
      private static final int S24 = 20;
  
      //
      // round 3 left rotates
      //
      private static final int S31 = 4;
      private static final int S32 = 11;
      private static final int S33 = 16;
      private static final int S34 = 23;
  
      //
      // round 4 left rotates
      //
      private static final int S41 = 6;
      private static final int S42 = 10;
      private static final int S43 = 15;
      private static final int S44 = 21;
  
      /*
       * rotate int x left n bits.
       */
      private int rotateLeft(int x, int n) {
          return (x << n) | (x >>> (32 - n));
      }
  
      /*
       * F, G, H and I are the basic MD5 functions.
       */
      private int F(int u, int v, int w) {
          return (u & v) | (~u & w);
      }
  
      private int G(int u, int v, int w) {
          return (u & w) | (v & ~w);
      }
  
      private int H(int u, int v, int w) {
          return u ^ v ^ w;
      }
  
      private int K(int u, int v, int w) {
          return v ^ (u | ~w);
      }
  
      protected void processBlock() {
          int a = H1;
          int b = H2;
          int c = H3;
          int d = H4;
  
          //
          // Round 1 - F cycle, 16 times.
          //
          a = rotateLeft((a + F(b, c, d) + X[0] + 0xd76aa478), S11) + b;
          d = rotateLeft((d + F(a, b, c) + X[1] + 0xe8c7b756), S12) + a;
          c = rotateLeft((c + F(d, a, b) + X[2] + 0x242070db), S13) + d;
          b = rotateLeft((b + F(c, d, a) + X[3] + 0xc1bdceee), S14) + c;
          a = rotateLeft((a + F(b, c, d) + X[4] + 0xf57c0faf), S11) + b;
          d = rotateLeft((d + F(a, b, c) + X[5] + 0x4787c62a), S12) + a;
          c = rotateLeft((c + F(d, a, b) + X[6] + 0xa8304613), S13) + d;
          b = rotateLeft((b + F(c, d, a) + X[7] + 0xfd469501), S14) + c;
          a = rotateLeft((a + F(b, c, d) + X[8] + 0x698098d8), S11) + b;
          d = rotateLeft((d + F(a, b, c) + X[9] + 0x8b44f7af), S12) + a;
          c = rotateLeft((c + F(d, a, b) + X[10] + 0xffff5bb1), S13) + d;
          b = rotateLeft((b + F(c, d, a) + X[11] + 0x895cd7be), S14) + c;
          a = rotateLeft((a + F(b, c, d) + X[12] + 0x6b901122), S11) + b;
          d = rotateLeft((d + F(a, b, c) + X[13] + 0xfd987193), S12) + a;
          c = rotateLeft((c + F(d, a, b) + X[14] + 0xa679438e), S13) + d;
          b = rotateLeft((b + F(c, d, a) + X[15] + 0x49b40821), S14) + c;
  
          //
          // Round 2 - G cycle, 16 times.
          //
          a = rotateLeft((a + G(b, c, d) + X[1] + 0xf61e2562), S21) + b;
          d = rotateLeft((d + G(a, b, c) + X[6] + 0xc040b340), S22) + a;
          c = rotateLeft((c + G(d, a, b) + X[11] + 0x265e5a51), S23) + d;
          b = rotateLeft((b + G(c, d, a) + X[0] + 0xe9b6c7aa), S24) + c;
          a = rotateLeft((a + G(b, c, d) + X[5] + 0xd62f105d), S21) + b;
          d = rotateLeft((d + G(a, b, c) + X[10] + 0x02441453), S22) + a;
          c = rotateLeft((c + G(d, a, b) + X[15] + 0xd8a1e681), S23) + d;
          b = rotateLeft((b + G(c, d, a) + X[4] + 0xe7d3fbc8), S24) + c;
          a = rotateLeft((a + G(b, c, d) + X[9] + 0x21e1cde6), S21) + b;
          d = rotateLeft((d + G(a, b, c) + X[14] + 0xc33707d6), S22) + a;
          c = rotateLeft((c + G(d, a, b) + X[3] + 0xf4d50d87), S23) + d;
          b = rotateLeft((b + G(c, d, a) + X[8] + 0x455a14ed), S24) + c;
          a = rotateLeft((a + G(b, c, d) + X[13] + 0xa9e3e905), S21) + b;
          d = rotateLeft((d + G(a, b, c) + X[2] + 0xfcefa3f8), S22) + a;
          c = rotateLeft((c + G(d, a, b) + X[7] + 0x676f02d9), S23) + d;
          b = rotateLeft((b + G(c, d, a) + X[12] + 0x8d2a4c8a), S24) + c;
  
          //
          // Round 3 - H cycle, 16 times.
          //
          a = rotateLeft((a + H(b, c, d) + X[5] + 0xfffa3942), S31) + b;
          d = rotateLeft((d + H(a, b, c) + X[8] + 0x8771f681), S32) + a;
          c = rotateLeft((c + H(d, a, b) + X[11] + 0x6d9d6122), S33) + d;
          b = rotateLeft((b + H(c, d, a) + X[14] + 0xfde5380c), S34) + c;
          a = rotateLeft((a + H(b, c, d) + X[1] + 0xa4beea44), S31) + b;
          d = rotateLeft((d + H(a, b, c) + X[4] + 0x4bdecfa9), S32) + a;
          c = rotateLeft((c + H(d, a, b) + X[7] + 0xf6bb4b60), S33) + d;
          b = rotateLeft((b + H(c, d, a) + X[10] + 0xbebfbc70), S34) + c;
          a = rotateLeft((a + H(b, c, d) + X[13] + 0x289b7ec6), S31) + b;
          d = rotateLeft((d + H(a, b, c) + X[0] + 0xeaa127fa), S32) + a;
          c = rotateLeft((c + H(d, a, b) + X[3] + 0xd4ef3085), S33) + d;
          b = rotateLeft((b + H(c, d, a) + X[6] + 0x04881d05), S34) + c;
          a = rotateLeft((a + H(b, c, d) + X[9] + 0xd9d4d039), S31) + b;
          d = rotateLeft((d + H(a, b, c) + X[12] + 0xe6db99e5), S32) + a;
          c = rotateLeft((c + H(d, a, b) + X[15] + 0x1fa27cf8), S33) + d;
          b = rotateLeft((b + H(c, d, a) + X[2] + 0xc4ac5665), S34) + c;
  
          //
          // Round 4 - K cycle, 16 times.
          //
          a = rotateLeft((a + K(b, c, d) + X[0] + 0xf4292244), S41) + b;
          d = rotateLeft((d + K(a, b, c) + X[7] + 0x432aff97), S42) + a;
          c = rotateLeft((c + K(d, a, b) + X[14] + 0xab9423a7), S43) + d;
          b = rotateLeft((b + K(c, d, a) + X[5] + 0xfc93a039), S44) + c;
          a = rotateLeft((a + K(b, c, d) + X[12] + 0x655b59c3), S41) + b;
          d = rotateLeft((d + K(a, b, c) + X[3] + 0x8f0ccc92), S42) + a;
          c = rotateLeft((c + K(d, a, b) + X[10] + 0xffeff47d), S43) + d;
          b = rotateLeft((b + K(c, d, a) + X[1] + 0x85845dd1), S44) + c;
          a = rotateLeft((a + K(b, c, d) + X[8] + 0x6fa87e4f), S41) + b;
          d = rotateLeft((d + K(a, b, c) + X[15] + 0xfe2ce6e0), S42) + a;
          c = rotateLeft((c + K(d, a, b) + X[6] + 0xa3014314), S43) + d;
          b = rotateLeft((b + K(c, d, a) + X[13] + 0x4e0811a1), S44) + c;
          a = rotateLeft((a + K(b, c, d) + X[4] + 0xf7537e82), S41) + b;
          d = rotateLeft((d + K(a, b, c) + X[11] + 0xbd3af235), S42) + a;
          c = rotateLeft((c + K(d, a, b) + X[2] + 0x2ad7d2bb), S43) + d;
          b = rotateLeft((b + K(c, d, a) + X[9] + 0xeb86d391), S44) + c;
  
          H1 += a;
          H2 += b;
          H3 += c;
          H4 += d;
  
          //
          // reset the offset and clean out the word buffer.
          //
          xOff = 0;
          for (int i = 0; i != X.length; i++) {
              X[i] = 0;
          }
      }
  }
  