content: package im.actor.crypto.primitives.digest;
  
  
  /**
   * 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();
      }
  
      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;
          }
      }
  }
  