/*
 * MD5 implementation
 * written Santeri Paavolainen, Helsinki Finland 1996
 * (c) Santeri Paavolainen, Helsinki Finland 1996
 * modifications Copyright (C) 2002-2004 Stephen Ostermiller
 * http://ostermiller.org/contact.pl?regarding=Java+Utilities
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * See COPYING.TXT for details.
 *
 * The original work by Santeri Paavolainen can be found at
 * http://www.helsinki.fi/~sjpaavol/programs/md5/
 *
 * This Java class has been derived from the RSA Data Security, Inc. MD5
 * Message-Digest Algorithm and its reference implementation.
 */
package ctmobup.utils;

import java.io.*;

/**
 * MD5 hash generator.
 * More information about this class is available from <a target="_top" href=
 * "http://ostermiller.org/utils/MD5.html">ostermiller.org</a>.
 * <p>
 * This class takes as input a message of arbitrary length and produces
 * as output a 128-bit "fingerprint" or "message digest" of the input.
 * It is conjectured that it is computationally infeasible to produce
 * two messages having the same message digest, or to produce any
 * message having a given pre-specified target message digest. The MD5
 * algorithm is intended for digital signature applications, where a
 * large file must be "compressed" in a secure manner before being
 * encrypted with a private (secret) key under a public-key cryptosystem
 * such as RSA.
 * <p>
 * For more information see RFC1321.
 *
 * @see MD5OutputStream
 * @see MD5InputStream
 *
 * @author Santeri Paavolainen http://www.helsinki.fi/~sjpaavol/programs/md5/
 * @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
 * @since ostermillerutils 1.00.00
 */
public class MD5 {

	/**
	 * Class constructor
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public MD5 () {
		reset();
	}

	

	/**
	 * Gets this hash sum as an array of 16 bytes.
	 *
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public byte[] getHash() {
		if (!finalState.valid) {
			finalState.copy(workingState);
			long bitCount = finalState.bitCount;
			// Compute the number of left over bits
			int leftOver = (int) (((bitCount >>> 3)) & 0x3f);
			// Compute the amount of padding to add based on number of left over bits.
			int padlen = (leftOver < 56) ? (56 - leftOver) : (120 - leftOver);
			// add the padding
			update(finalState, padding, 0, padlen);
			// add the length (computed before padding was added)
			update(finalState, encode(bitCount), 0, 8);
			finalState.valid = true;
		}
		// make a copy of the hash before returning it.
		return encode(finalState.state, 16);
	}

	/**
	 * Returns 32-character hex representation of this hash.
	 *
	 * @return String representation of this object's hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public String getHashString(){
		return toHex(this.getHash());
	}

	/**
	 * Gets the MD5 hash of the given byte array.
	 *
	 * @param b byte array for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(byte[] b){
		MD5 md5 = new MD5();
		md5.update(b);
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash of the given byte array.
	 *
	 * @param b byte array for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(byte[] b){
		MD5 md5 = new MD5();
		md5.update(b);
		return md5.getHashString();
	}

	/**
	 * Gets the MD5 hash the data on the given InputStream.
	 *
	 * @param in byte array for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 * @throws IOException if an I/O error occurs.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(InputStream in) throws IOException {
		MD5 md5 = new MD5();
		byte[] buffer = new byte[1024];
		int read;
		while ((read = in.read(buffer)) != -1){
			md5.update(buffer, read);
		}
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash the data on the given InputStream.
	 *
	 * @param in byte array for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 * @throws IOException if an I/O error occurs.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(InputStream in) throws IOException {
		MD5 md5 = new MD5();
		byte[] buffer = new byte[1024];
		int read;
		while ((read = in.read(buffer)) != -1){
			md5.update(buffer, read);
		}
		return md5.getHashString();
	}

	
	/**
	 * Gets the MD5 hash of the given String.
	 * The string is converted to bytes using the current
	 * platform's default character encoding.
	 *
	 * @param s String for which an MD5 hash is desired.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(String s){
		MD5 md5 = new MD5();
		md5.update(s);
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash of the given String.
	 * The string is converted to bytes using the current
	 * platform's default character encoding.
	 *
	 * @param s String for which an MD5 hash is desired.
	 * @return 32-character hex representation the data's MD5 hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(String s){
		MD5 md5 = new MD5();
		md5.update(s);
		return md5.getHashString();
	}


	/**
	 * Gets the MD5 hash of the given String.
	 *
	 * @param s String for which an MD5 hash is desired.
	 * @param enc The name of a supported character encoding.
	 * @return Array of 16 bytes, the hash of all updated bytes.
	 * @throws UnsupportedEncodingException If the named encoding is not supported.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static byte[] getHash(String s, String enc) throws UnsupportedEncodingException {
		MD5 md5 = new MD5();
		md5.update(s, enc);
		return md5.getHash();
	}

	/**
	 * Gets the MD5 hash of the given String.
	 *
	 * @param s String for which an MD5 hash is desired.
	 * @param enc The name of a supported character encoding.
	 * @return 32-character hex representation the data's MD5 hash.
	 * @throws UnsupportedEncodingException If the named encoding is not supported.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public static String getHashString(String s, String enc) throws UnsupportedEncodingException {
		MD5 md5 = new MD5();
		md5.update(s, enc);
		return md5.getHashString();
	}


	/**
	 * Reset the MD5 sum to its initial state.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void reset() {
		workingState.reset();
		finalState.valid = false;
	}

	/**
	 * Returns 32-character hex representation of this hash.
	 *
	 * @return String representation of this object's hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public String toString(){
		return getHashString();
	}

	/**
	 * Update this hash with the given data.
	 * <p>
	 * A state may be passed into this method so that we can add padding
	 * and finalize a md5 hash without limiting our ability to update
	 * more data later.
	 * <p>
	 * If length bytes are not available to be hashed, as many bytes as
	 * possible will be hashed.
	 *
	 * @param state Which state is updated.
	 * @param buffer Array of bytes to be hashed.
	 * @param offset Offset to buffer array.
	 * @param length number of bytes to hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private void update (MD5State state, byte buffer[], int offset, int length) {

		finalState.valid = false;

		// if length goes beyond the end of the buffer, cut it short.
		if ((length + offset) > buffer.length){
			length = buffer.length - offset;
		}

		// compute number of bytes mod 64
		// this is what we have sitting in a buffer
		// that have not been hashed yet
		int index = (int) (state.bitCount >>> 3) & 0x3f;

		// add the length to the count (translate bytes to bits)
		state.bitCount += length << 3;

		int partlen = 64 - index;

		int i = 0;
		if (length >= partlen) {
			System.arraycopy(buffer, offset, state.buffer, index, partlen);
			transform(state, decode(state.buffer, 64, 0));
			for (i = partlen; (i + 63) < length; i+= 64){
				transform(state, decode(buffer, 64, i));
			}
			index = 0;
		}

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

	/**
	 * Update this hash with the given data.
	 * <p>
	 * If length bytes are not available to be hashed, as many bytes as
	 * possible will be hashed.
	 *
	 * @param buffer Array of bytes to be hashed.
	 * @param offset Offset to buffer array.
	 * @param length number of bytes to hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (byte buffer[], int offset, int length) {
		update(workingState, buffer, offset, length);
	}

	/**
	 * Update this hash with the given data.
	 * <p>
	 * If length bytes are not available to be hashed, as many bytes as
	 * possible will be hashed.
	 *
	 * @param buffer Array of bytes to be hashed.
	 * @param length number of bytes to hash.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (byte buffer[], int length) {
		update(buffer, 0, length);
	}

	/**
	 * Update this hash with the given data.
	 *
	 * @param buffer Array of bytes to be hashed.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (byte buffer[]) {
		update(buffer, 0, buffer.length);
	}

	/**
	 * Updates this hash with a single byte.
	 *
	 * @param b byte to be hashed.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (byte b) {
		byte buffer[] = new byte[1];
		buffer[0] = b;
		update(buffer, 1);
	}

	/**
	 * Update this hash with a long.
	 * This hash will be updated in a little endian order with the
	 * the least significant byte going first.
	 *
	 * @param l long to be hashed.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private void update (MD5State state, long l) {
		update(
			state,
			new byte[] {
				(byte)((l >>> 0) & 0xff),
				(byte)((l >>> 8) & 0xff),
				(byte)((l >>> 16) & 0xff),
				(byte)((l >>> 24) & 0xff),
				(byte)((l >>> 32) & 0xff),
				(byte)((l >>> 40) & 0xff),
				(byte)((l >>> 48) & 0xff),
				(byte)((l >>> 56) & 0xff),
			},
			0,
			8
		);
	}

	/**
	 * Update this hash with a String.
	 * The string is converted to bytes using the current
	 * platform's default character encoding.
	 *
	 * @param s String to be hashed.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (String s) {
		update(s.getBytes());
	}

	/**
	 * Update this hash with a String.
	 *
	 * @param s String to be hashed.
	 * @param enc The name of a supported character encoding.
	 * @throws UnsupportedEncodingException If the named encoding is not supported.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	public void update (String s, String enc) throws UnsupportedEncodingException {
		update(s.getBytes(enc));
	}

	/**
	 * The current state from which the hash sum
	 * can be computed or updated.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private MD5State workingState = new MD5State();

	/**
	 * Cached copy of the final MD5 hash sum.  This is created when
	 * the hash is requested and it is invalidated when the hash
	 * is updated.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private MD5State finalState = new MD5State();

	/**
	 * Temporary buffer cached here for performance reasons.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private int[] decodeBuffer = new int[16];

	/**
	 * 64 bytes of padding that can be added if the length
	 * is not divisible by 64.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private static final byte padding[] = {
		(byte) 0x80, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
				0, 0, 0, 0, 0, 0, 0, 0,
	};

	/**
	 * Contains internal state of the MD5 class.
	 * Passes MD5 test suite as defined in RFC1321.
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private class MD5State {

		/**
		 * True if this state is valid.
		 *
		 * @since ostermillerutils 1.00.00
		 */
		public boolean valid = true;

		/**
		 * Reset to initial state.
		 *
		 * @since ostermillerutils 1.00.00
		 */
		public void reset(){
			state[0] = 0x67452301;
			state[1] = 0xefcdab89;
			state[2] = 0x98badcfe;
			state[3] = 0x10325476;

			bitCount = 0;
		}

		/**
		 * 128-byte state
		 *
		 * @since ostermillerutils 1.00.00
		 */
		public int state[] = new int[4];

		/**
		 * 64-bit count of the number of bits that have been hashed.
		 *
		 * @since ostermillerutils 1.00.00
		 */
		public long bitCount;

		/**
		 * 64-byte buffer (512 bits) for storing to-be-hashed characters
		 *
		 * @since ostermillerutils 1.00.00
		 */
		public byte buffer[] = new byte[64];

		public MD5State() {
			reset();
		}

		/**
		 * Set this state to be exactly the same as some other.
		 *
		 * @param from state to copy from.
		 *
		 * @since ostermillerutils 1.00.00
		 */
		public void copy(MD5State from) {
			System.arraycopy(from.buffer, 0, this.buffer, 0, this.buffer.length);
			System.arraycopy(from.state, 0, this.state, 0, this.state.length);
			this.valid = from.valid;
			this.bitCount = from.bitCount;
		}

		public String toString(){
			return state[0] + " " + state[1] + " " + state[2] + " " + state[3];
		}
	}


	/**
	 * Turns array of bytes into string representing each byte as
	 * a two digit unsigned hex number.
	 *
	 * @param hash Array of bytes to convert to hex-string
	 * @return  Generated hex string
	 *
	 * @since ostermillerutils 1.00.00
	 */
	private static String toHex(byte hash[]){
		StringBuffer buf = new StringBuffer(hash.length * 2);
		for (int i=0; i<hash.length; i++){
			int intVal = hash[i] & 0xff;
			if (intVal < 0x10){
				// append a zero before a one digit hex
				// number to make it two digits.
				buf.append("0");
			}
			buf.append(Integer.toHexString(intVal));
		}
		return buf.toString();
	}

	private static int FF (int a, int b, int c, int d, int x, int s, int ac) {
		a += ((b & c) | (~b & d));
		a += x;
		a += ac;
		//return rotateLeft(a, s) + b;
		a = (a << s) | (a >>> (32 - s));
		return a + b;
	}

	private static int GG (int a, int b, int c, int d, int x, int s, int ac) {
		a += ((b & d) | (c & ~d));
		a += x;
		a += ac;
		//return rotateLeft(a, s) + b;
		a = (a << s) | (a >>> (32 - s));
		return a + b;
	}

	private static int HH (int a, int b, int c, int d, int x, int s, int ac) {
		a += (b ^ c ^ d);
		a += x;
		a += ac;
		//return rotateLeft(a, s) + b;
		a = (a << s) | (a >>> (32 - s));
		return a + b;
	}

	private static int II (int a, int b, int c, int d, int x, int s, int ac) {
		a += (c ^ (b | ~d));
		a += x;
		a += ac;
		//return rotateLeft(a, s) + b;
		a = (a << s) | (a >>> (32 - s));
		return a + b;
	}

	private static byte[] encode(long l){
		byte[] out = new byte[8];
		out[0] = (byte) (l & 0xff);
		out[1] = (byte) ((l >>> 8) & 0xff);
		out[2] = (byte) ((l >>> 16) & 0xff);
		out[3] = (byte) ((l >>> 24) & 0xff);
		out[4] = (byte) ((l >>> 32) & 0xff);
		out[5] = (byte) ((l >>> 40) & 0xff);
		out[6] = (byte) ((l >>> 48) & 0xff);
		out[7] = (byte) ((l >>> 56) & 0xff);
		return out;
	}

	private static byte[] encode(int input[], int len){
		byte[] out = new byte[len];
		int i, j;
		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;
	}

	private int[] decode(byte buffer[], int len, int offset){
		int i, j;
		for (i = j = 0; j < len; i++, j += 4) {
			decodeBuffer[i] = (
				(int) (buffer[j + offset] & 0xff)) |
				(((int) (buffer[j + 1 + offset] & 0xff)) << 8) |
				(((int) (buffer[j + 2 + offset] & 0xff)) << 16) |
				(((int) (buffer[j + 3 + offset] & 0xff)) << 24
			);
		}
		return decodeBuffer;
	}

	private static void transform(MD5State state, int[] x){
		int a = state.state[0];
		int b = state.state[1];
		int c = state.state[2];
		int d = state.state[3];

		/* Round 1 */
		a = FF (a, b, c, d, x[ 0],   7, 0xd76aa478); /* 1 */
		d = FF (d, a, b, c, x[ 1],  12, 0xe8c7b756); /* 2 */
		c = FF (c, d, a, b, x[ 2],  17, 0x242070db); /* 3 */
		b = FF (b, c, d, a, x[ 3],  22, 0xc1bdceee); /* 4 */
		a = FF (a, b, c, d, x[ 4],   7, 0xf57c0faf); /* 5 */
		d = FF (d, a, b, c, x[ 5],  12, 0x4787c62a); /* 6 */
		c = FF (c, d, a, b, x[ 6],  17, 0xa8304613); /* 7 */
		b = FF (b, c, d, a, x[ 7],  22, 0xfd469501); /* 8 */
		a = FF (a, b, c, d, x[ 8],   7, 0x698098d8); /* 9 */
		d = FF (d, a, b, c, x[ 9],  12, 0x8b44f7af); /* 10 */
		c = FF (c, d, a, b, x[10],  17, 0xffff5bb1); /* 11 */
		b = FF (b, c, d, a, x[11],  22, 0x895cd7be); /* 12 */
		a = FF (a, b, c, d, x[12],   7, 0x6b901122); /* 13 */
		d = FF (d, a, b, c, x[13],  12, 0xfd987193); /* 14 */
		c = FF (c, d, a, b, x[14],  17, 0xa679438e); /* 15 */
		b = FF (b, c, d, a, x[15],  22, 0x49b40821); /* 16 */

		/* Round 2 */
		a = GG (a, b, c, d, x[ 1],   5, 0xf61e2562); /* 17 */
		d = GG (d, a, b, c, x[ 6],   9, 0xc040b340); /* 18 */
		c = GG (c, d, a, b, x[11],  14, 0x265e5a51); /* 19 */
		b = GG (b, c, d, a, x[ 0],  20, 0xe9b6c7aa); /* 20 */
		a = GG (a, b, c, d, x[ 5],   5, 0xd62f105d); /* 21 */
		d = GG (d, a, b, c, x[10],   9, 0x02441453); /* 22 */
		c = GG (c, d, a, b, x[15],  14, 0xd8a1e681); /* 23 */
		b = GG (b, c, d, a, x[ 4],  20, 0xe7d3fbc8); /* 24 */
		a = GG (a, b, c, d, x[ 9],   5, 0x21e1cde6); /* 25 */
		d = GG (d, a, b, c, x[14],   9, 0xc33707d6); /* 26 */
		c = GG (c, d, a, b, x[ 3],  14, 0xf4d50d87); /* 27 */
		b = GG (b, c, d, a, x[ 8],  20, 0x455a14ed); /* 28 */
		a = GG (a, b, c, d, x[13],   5, 0xa9e3e905); /* 29 */
		d = GG (d, a, b, c, x[ 2],   9, 0xfcefa3f8); /* 30 */
		c = GG (c, d, a, b, x[ 7],  14, 0x676f02d9); /* 31 */
		b = GG (b, c, d, a, x[12],  20, 0x8d2a4c8a); /* 32 */

		/* Round 3 */
		a = HH (a, b, c, d, x[ 5],   4, 0xfffa3942); /* 33 */
		d = HH (d, a, b, c, x[ 8],  11, 0x8771f681); /* 34 */
		c = HH (c, d, a, b, x[11],  16, 0x6d9d6122); /* 35 */
		b = HH (b, c, d, a, x[14],  23, 0xfde5380c); /* 36 */
		a = HH (a, b, c, d, x[ 1],   4, 0xa4beea44); /* 37 */
		d = HH (d, a, b, c, x[ 4],  11, 0x4bdecfa9); /* 38 */
		c = HH (c, d, a, b, x[ 7],  16, 0xf6bb4b60); /* 39 */
		b = HH (b, c, d, a, x[10],  23, 0xbebfbc70); /* 40 */
		a = HH (a, b, c, d, x[13],   4, 0x289b7ec6); /* 41 */
		d = HH (d, a, b, c, x[ 0],  11, 0xeaa127fa); /* 42 */
		c = HH (c, d, a, b, x[ 3],  16, 0xd4ef3085); /* 43 */
		b = HH (b, c, d, a, x[ 6],  23, 0x04881d05); /* 44 */
		a = HH (a, b, c, d, x[ 9],   4, 0xd9d4d039); /* 45 */
		d = HH (d, a, b, c, x[12],  11, 0xe6db99e5); /* 46 */
		c = HH (c, d, a, b, x[15],  16, 0x1fa27cf8); /* 47 */
		b = HH (b, c, d, a, x[ 2],  23, 0xc4ac5665); /* 48 */

		/* Round 4 */
		a = II (a, b, c, d, x[ 0],   6, 0xf4292244); /* 49 */
		d = II (d, a, b, c, x[ 7],  10, 0x432aff97); /* 50 */
		c = II (c, d, a, b, x[14],  15, 0xab9423a7); /* 51 */
		b = II (b, c, d, a, x[ 5],  21, 0xfc93a039); /* 52 */
		a = II (a, b, c, d, x[12],   6, 0x655b59c3); /* 53 */
		d = II (d, a, b, c, x[ 3],  10, 0x8f0ccc92); /* 54 */
		c = II (c, d, a, b, x[10],  15, 0xffeff47d); /* 55 */
		b = II (b, c, d, a, x[ 1],  21, 0x85845dd1); /* 56 */
		a = II (a, b, c, d, x[ 8],   6, 0x6fa87e4f); /* 57 */
		d = II (d, a, b, c, x[15],  10, 0xfe2ce6e0); /* 58 */
		c = II (c, d, a, b, x[ 6],  15, 0xa3014314); /* 59 */
		b = II (b, c, d, a, x[13],  21, 0x4e0811a1); /* 60 */
		a = II (a, b, c, d, x[ 4],   6, 0xf7537e82); /* 61 */
		d = II (d, a, b, c, x[11],  10, 0xbd3af235); /* 62 */
		c = II (c, d, a, b, x[ 2],  15, 0x2ad7d2bb); /* 63 */
		b = II (b, c, d, a, x[ 9],  21, 0xeb86d391); /* 64 */

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