md5.java

OA典型例子

    b = ((b << 23) | (b >>> 9)) + c;

    a += (b ^ c ^ d) + x[13] + 0x289b7ec6;      /* 41 */
    a = ((a << 4) | (a >>> 28)) + b;
    d += (a ^ b ^ c) + x[ 0] + 0xeaa127fa;      /* 42 */
    d = ((d << 11) | (d >>> 21)) + a;
    c += (d ^ a ^ b) + x[ 3] + 0xd4ef3085;      /* 43 */
    c = ((c << 16) | (c >>> 16)) + d;
    b += (c ^ d ^ a) + x[ 6] + 0x04881d05;      /* 44 */
    b = ((b << 23) | (b >>> 9)) + c;

    a += (b ^ c ^ d) + x[ 9] + 0xd9d4d039;      /* 33 */
    a = ((a << 4) | (a >>> 28)) + b;
    d += (a ^ b ^ c) + x[12] + 0xe6db99e5;      /* 34 */
    d = ((d << 11) | (d >>> 21)) + a;
    c += (d ^ a ^ b) + x[15] + 0x1fa27cf8;      /* 35 */
    c = ((c << 16) | (c >>> 16)) + d;
    b += (c ^ d ^ a) + x[ 2] + 0xc4ac5665;      /* 36 */
    b = ((b << 23) | (b >>> 9)) + c;


    /* Round 4 */
    a += (c ^ (b | ~d)) + x[ 0] + 0xf4292244; /* 49 */
    a = ((a << 6) | (a >>> 26)) + b;
    d += (b ^ (a | ~c)) + x[ 7] + 0x432aff97; /* 50 */
    d = ((d << 10) | (d >>> 22)) + a;
    c += (a ^ (d | ~b)) + x[14] + 0xab9423a7; /* 51 */
    c = ((c << 15) | (c >>> 17)) + d;
    b += (d ^ (c | ~a)) + x[ 5] + 0xfc93a039; /* 52 */
    b = ((b << 21) | (b >>> 11)) + c;

    a += (c ^ (b | ~d)) + x[12] + 0x655b59c3; /* 53 */
    a = ((a << 6) | (a >>> 26)) + b;
    d += (b ^ (a | ~c)) + x[ 3] + 0x8f0ccc92; /* 54 */
    d = ((d << 10) | (d >>> 22)) + a;
    c += (a ^ (d | ~b)) + x[10] + 0xffeff47d; /* 55 */
    c = ((c << 15) | (c >>> 17)) + d;
    b += (d ^ (c | ~a)) + x[ 1] + 0x85845dd1; /* 56 */
    b = ((b << 21) | (b >>> 11)) + c;

    a += (c ^ (b | ~d)) + x[ 8] + 0x6fa87e4f; /* 57 */
    a = ((a << 6) | (a >>> 26)) + b;
    d += (b ^ (a | ~c)) + x[15] + 0xfe2ce6e0; /* 58 */
    d = ((d << 10) | (d >>> 22)) + a;
    c += (a ^ (d | ~b)) + x[ 6] + 0xa3014314; /* 59 */
    c = ((c << 15) | (c >>> 17)) + d;
    b += (d ^ (c | ~a)) + x[13] + 0x4e0811a1; /* 60 */
    b = ((b << 21) | (b >>> 11)) + c;

    a += (c ^ (b | ~d)) + x[ 4] + 0xf7537e82; /* 61 */
    a = ((a << 6) | (a >>> 26)) + b;
    d += (b ^ (a | ~c)) + x[11] + 0xbd3af235; /* 62 */
    d = ((d << 10) | (d >>> 22)) + a;
    c += (a ^ (d | ~b)) + x[ 2] + 0x2ad7d2bb; /* 63 */
    c = ((c << 15) | (c >>> 17)) + d;
    b += (d ^ (c | ~a)) + x[ 9] + 0xeb86d391; /* 64 */
    b = ((b << 21) | (b >>> 11)) + c;

    state.state[0] += a;
    state.state[1] += b;
    state.state[2] += c;
    state.state[3] += d;
  }

  /**
   * Updates hash with the bytebuffer given (using at maximum length bytes from
   * that buffer)
   *
   * @param state	Which state is updated
   * @param buffer	Array of bytes to be hashed
   * @param offset	Offset to buffer array
   * @param length	Use at maximum `length' bytes (absolute
   *			maximum is buffer.length)
   */
  public void Update (MD5State stat, byte buffer[], int offset, int length) {
    int	index, partlen, i, start;
    finals = null;

    /* Length can be told to be shorter, but not inter */
    if ((length - offset)> buffer.length)
      length = buffer.length - offset;

    /* compute number of bytes mod 64 */

    index = (int) (stat.count & 0x3f);
    stat.count += length;

    partlen = 64 - index;

    if (length >= partlen) {
      for (i = 0; i < partlen; i++)
	stat.buffer[i + index] = buffer[i + offset];

      int[] decode_buf = new int[16];
      Transform(stat, stat.buffer, 0, decode_buf);

      for (i = partlen; (i + 63) < length; i+= 64)
	Transform(stat, buffer, i + offset, decode_buf);

      index = 0;
    } else
      i = 0;

    /* buffer remaining input */
    if (i < length) {
      start = i;
      for (; i < length; i++)
	stat.buffer[index + i - start] = buffer[i + offset];
    }
  }

  /*
   * Update()s for other datatypes than byte[] also. Update(byte[], int)
   * is only the main driver.
   */

  /**
   * Plain update, updates this object
   */

  public void Update (byte buffer[], int offset, int length) {
      Update(this.state, buffer, offset, length);
  }

  public void Update (byte buffer[], int length) {
      Update(this.state, buffer, 0, length);
  }

  /**
   * Updates hash with given array of bytes
   *
   * @param buffer	Array of bytes to use for updating the hash
   */
  public void Update (byte buffer[]) {
      Update(buffer, 0, buffer.length);
  }

  /**
   * Updates hash with a single byte
   *
   * @param b		Single byte to update the hash
   */
  public void Update (byte b) {
    byte buffer[] = new byte[1];
    buffer[0] = b;

    Update(buffer, 1);
  }

  /**
   * Update buffer with given string.  Note that because the version of
   * the s.getBytes() method without parameters is used to convert the
   * string to a byte array, the results of this method may be different
   * on different platforms.  The s.getBytes() method converts the string
   * into a byte array using the current platform's default character set
   * and may therefore have different results on platforms with different
   * default character sets.  If a version that works consistently
   * across platforms with different default character sets is desired,
   * use the overloaded version of the Update() method which takes a
   * string and a character encoding.
   *
   * @param s		String to be update to hash (is used as
   *		       	s.getBytes())
   */
  public void Update (String s) {
    byte chars[] = s.getBytes();
    Update(chars, chars.length);
  }

  /**
   * Update buffer with given string using the given encoding.  If the
   * given encoding is null, the encoding "ISO8859_1" is used.
   *
   * @param s		String to be update to hash (is used as
   *		       	s.getBytes(charset_name))
   * @param charset_name The character set to use to convert s to a
   *                    byte array, or null if the "ISO8859_1"
   *                    character set is desired.
   * @exception         java.io.UnsupportedEncodingException If the named
   *                    charset is not supported.
   */
  public void Update (String s, String charset_name) throws java.io.UnsupportedEncodingException {
    if (charset_name == null) charset_name = "ISO8859_1";
    byte chars[] = s.getBytes(charset_name);
    Update(chars, chars.length);
  }

  /**
   * Update buffer with a single integer (only & 0xff part is used,
   * as a byte)
   *
   * @param i		Integer value, which is then converted to
   *			byte as i & 0xff
   */

  public void Update (int i) {
      Update((byte) (i & 0xff));
  }

  private byte[] Encode (int input[], int len) {
    int		i, j;
    byte	out[];

    out = new byte[len];

    for (i = j = 0; j  < len; i++, j += 4) {
      out[j] = (byte) (input[i] & 0xff);
      out[j + 1] = (byte) ((input[i] >>> 8) & 0xff);
      out[j + 2] = (byte) ((input[i] >>> 16) & 0xff);
      out[j + 3] = (byte) ((input[i] >>> 24) & 0xff);
    }

    return out;
  }

  /**
   * Returns array of bytes (16 bytes) representing hash as of the
   * current state of this object. Note: getting a hash does not
   * invalidate the hash object, it only creates a copy of the real
   * state which is finalized.
   *
   * @return	Array of 16 bytes, the hash of all updated bytes
   */
  public synchronized byte[] Final () {
    byte	bits[];
    int		index, padlen;
    MD5State	fin;

    if (finals == null) {
      fin = new MD5State(state);

      int[] count_ints = {(int) (fin.count << 3), (int) (fin.count >> 29)};
      bits = Encode(count_ints, 8);

      index = (int) (fin.count & 0x3f);
      padlen = (index < 56) ? (56 - index) : (120 - index);

      Update(fin, padding, 0, padlen);
      Update(fin, bits, 0, 8);

      /* Update() sets finals to null */
      finals = fin;
    }

    return Encode(finals.state, 16);
  }

  /**
   * Turns array of bytes into string representing each byte as
   * unsigned hex number.
   *
   * @param hash	Array of bytes to convert to hex-string
   * @return	Generated hex string
   */
  public static String asHex (byte hash[]) {
    StringBuffer buf = new StringBuffer(hash.length * 2);
    int i;

    for (i = 0; i < hash.length; i++) {
      if (((int) hash[i] & 0xff) < 0x10)
	buf.append("0");

      buf.append(Long.toString((int) hash[i] & 0xff, 16));
    }

    return buf.toString();
  }

  /**
   * Returns 32-character hex representation of this objects hash
   *
   * @return String of this object's hash
   */
  public String asHex () {
    return asHex(this.Final());
  }

}