// Md5.java
// $Id: Md5.java,v 1.3 1999/04/07 07:51:21 ylafon Exp $
// (c) COPYRIGHT MIT and INRIA, 1996.
// Please first read the full copyright statement in file COPYRIGHT.html

package org.w3c.tools.crypt ;

import java.io.* ;

public class Md5 {
    private static final int BUFFER_SIZE = 1024 ;

    private static final int S11 = 7 ;
    private static final int S12 = 12 ;
    private static final int S13 = 17 ;
    private static final int S14 = 22 ;
    private static final int S21 = 5 ;
    private static final int S22 = 9 ;
    private static final int S23 = 14 ;
    private static final int S24 = 20 ;
    private static final int S31 = 4 ;
    private static final int S32 = 11 ;
    private static final int S33 = 16 ;
    private static final int S34 = 23 ;
    private static final int S41 = 6 ;
    private static final int S42 = 10 ;
    private static final int S43 = 15 ;
    private static final int S44 = 21 ;

    private static byte padding[] = {
	(byte) 0x80, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, 
	(byte) 0, (byte) 0, (byte) 0, (byte) 0
    } ;


    private InputStream in       = null ;
    private boolean     stringp  = false ;
    private int         state[]  = null ;
    private long        count    = 0 ;
    private byte        buffer[] = null ;
    private byte        digest[] = null ;

    private static String stringify (byte buf[]) {
	StringBuffer sb = new StringBuffer(2*buf.length) ;
	for (int i = 0 ; i < buf.length; i++) {
	    int h = (buf[i] & 0xf0) >> 4 ;
	    int l = (buf[i] & 0x0f) ;
	    sb.append (new Character((char)((h>9) ? 'a'+h-10 : '0'+h))) ;
	    sb.append (new Character((char)((l>9) ? 'a'+l-10 : '0'+l))) ;
	}
	return sb.toString() ;
    }

    private final int F(int x, int y, int z) {
	return ((x & y) | ((~x) & z)) ;
    }

    private final int G(int x, int y, int z) {
	return ((x & z) | (y & (~z))) ;
    }

    private final int H(int x, int y, int z) {
	return (x ^ y ^ z) ;
    }
    
    private final int I(int x, int y, int z) {
	return (y ^ (x | (~z))) ;
    }
    
    private final int  rotate_left(int x, int n) {
	return ((x << n) | (x >>> (32-n))) ;
    }

    private final int FF(int a,int b,int c,int d,int x,int s,int ac) {
	a += (F(b, c, d) + x + ac) ;
	a = rotate_left(a, s) ;
	a += b ;
	return a ;
    }

    private final int GG(int a,int b,int c,int d,int x,int s,int ac) {
	a += (G(b, c, d) + x + ac) ;
	a = rotate_left(a, s) ;
	a += b ;
	return a ;
    }

    private final int HH(int a,int b,int c,int d,int x,int s,int ac) {
	a += (H(b, c, d) + x + ac) ;
	a = rotate_left(a, s) ;
	a += b ;
	return a ;
    }

    private final int II(int a,int b,int c,int d,int x,int s,int ac) {
	a += (I(b, c, d) + x + ac) ;
	a = rotate_left(a, s) ;
	a += b ;
	return a;
    }
    
    private final void decode (int output[], byte input[], int off, int len) {
	int i = 0 ;
	int j = 0 ;
	for ( ; j < len; i++, j += 4) {
	    output[i] = (((int) (input[off+j]&0xff))
			 | (((int) (input[off+j+1] & 0xff)) << 8)
			 | (((int) (input[off+j+2] & 0xff)) << 16)
			 | (((int) (input[off+j+3] & 0xff)) << 24)) ;
	}
    }

    private final void transform (byte block[], int offset) {
	int a   = state[0] ;
	int b   = state[1] ;
	int c   = state[2] ;
	int d   = state[3] ;
	int x[] = new int[16] ;

	decode (x, block, offset, 64);
	/* Round 1 */
	a = FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
	d = FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
	c = FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
	b = FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
	a = FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
	d = FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
	c = FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
	b = FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
	a = FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
	d = FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
	c = FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
	b = FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
	a = FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
	d = FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
	c = FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
	b = FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
	/* Round 2 */
	a = GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
	d = GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
	c = GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
	b = GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
	a = GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
	d = GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
	c = GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
	b = GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
	a = GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
	d = GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
	c = GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
	b = GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
	a = GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
	d = GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
	c = GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
	b = GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
	
	/* Round 3 */
	a = HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
	d = HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
	c = HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
	b = HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
	a = HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
	d = HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
	c = HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
	b = HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
	a = HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
	d = HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
	c = HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
	b = HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
	a = HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
	d = HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
	c = HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
	b = HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
	
	/* Round 4 */
	a = II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
	d = II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
	c = II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
	b = II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
	a = II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
	d = II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
	c = II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
	b = II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
	a = II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
	d = II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
	c = II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
	b = II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
	a = II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
	d = II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
	c = II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
	b = II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */

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

    private final void update (byte input[], int len) {
	int index = ((int) (count >> 3)) & 0x3f ;
	count += (len << 3) ;
	int partLen = 64 - index ;
	int i = 0 ;
	if ( len >= partLen ) {
	    System.arraycopy (input, 0, buffer, index, partLen) ;
	    transform (buffer, 0) ;
	    for (i = partLen ; i + 63 < len ; i+= 64) 
		transform (input, i) ;
	    index = 0 ;
	} else {
	    i = 0 ;
	}
	System.arraycopy (input, i, buffer, index, len - i) ;
    }

    private byte[] end () {
	byte bits[] = new byte[8] ;
	for (int i = 0 ; i < 8 ; i++)
	    bits[i] = (byte) ((count>>>(i*8)) & 0xff) ;
	int index  = ((int) (count >> 3)) & 0x3f ;
	int padlen = (index < 56) ? (56 - index) : (120 - index) ;
	update (padding, padlen) ;
	update (bits, 8) ;
	return encode(state, 16) ;
    }

    // Encode the content.state array into 16 bytes array
    private byte[] encode (int input[], int len) {
	byte output[] = new byte[len] ;
	int i = 0 ;
	int j = 0 ;
	for ( ; j < len ; i++, j+= 4) {
	    output[j]   = (byte) ((input[i]      ) & 0xff) ;
	    output[j+1] = (byte) ((input[i] >> 8 ) & 0xff) ;
	    output[j+2] = (byte) ((input[i] >> 16) & 0xff) ;
	    output[j+3] = (byte) ((input[i] >> 24) & 0xff) ;
	}
	return output ;
    }

    /**
     * Get the digest for our input stream.
     * This method constructs the input stream digest, and return it, as a
     * a String, following the MD5 (rfc1321) algorithm,
     * @return An instance of String, giving the message digest.
     * @exception IOException Thrown if the digestifier was unable to read the
     *    input stream.
     */

    public byte[] getDigest ()
	throws IOException 
    {
	byte buffer[] = new byte[BUFFER_SIZE] ;
	int  got      = -1 ;

	if ( digest != null )
	    return digest ;
	while ((got = in.read(buffer)) > 0 ) 
	    update (buffer, got) ;
	this.digest = end () ;
	return digest ;
    }

    /**
     * Get the digest, for this string digestifier.
     * This method doesn't throw any IOException, since it knows that the
     * underlying stream ws built from a String.
     */

    public byte[] processString () {
	if ( ! stringp ) 
	    throw new RuntimeException (this.getClass().getName()
					+ "[processString]"
					+ " not a string.") ;
	try {
	    return getDigest() ;
	} catch (IOException ex) {
	}
	throw new RuntimeException (this.getClass().getName()
				    + "[processString]"
				    + ": implementation error.") ;
    }

    /**
     * Get the digest, as a proper string.
     */

    public String getStringDigest() {
	if ( digest == null )
	    throw new RuntimeException (this.getClass().getName()
					+ "[getStringDigest]"
					+ ": called before processing.") ;
	return stringify (digest) ;
    }


    /**
     * Construct a digestifier for the given string.
     * @param input The string to be digestified.
     * @param encoding the encoding name used (such as UTF8)
     */

    public Md5 (String input, String enc) {
 	byte bytes [] = null;
	try {
	    bytes = input.getBytes (enc);
	} catch(UnsupportedEncodingException e){
	    throw new RuntimeException("no "+enc+" encoding!!!");
	}
	this.stringp = true ;
	this.in      = new ByteArrayInputStream (bytes) ;
	this.state   = new int[4] ;
	this.buffer  = new byte[64] ;
	this.count   = 0 ;
	state[0] = 0x67452301;
	state[1] = 0xefcdab89;
	state[2] = 0x98badcfe;
	state[3] = 0x10325476;
    }   

    /**
     * Construct a digestifier for the given string.
     * @param input The string to be digestified.
     */

    public Md5 (String input) {
	this(input, "UTF8");
    }

    /**
     * Construct a digestifier for the given input stream.
     * @param in The input stream to be digestified.
     */

    public Md5 (InputStream in) {
	this.stringp = false ;
	this.in      = in ;
	this.state   = new int[4] ;
	this.buffer  = new byte[64] ;
	this.count   = 0 ;
	state[0] = 0x67452301;
	state[1] = 0xefcdab89;
	state[2] = 0x98badcfe;
	state[3] = 0x10325476;
    }

    public static void main (String args[]) 
	throws IOException
    {
	if ( args.length != 1) {
	    System.out.println ("Md5 <string>") ;
	    System.exit (1) ;
	}
	Md5 md5 = new Md5 (args[0]) ;
	md5.processString() ;
	System.out.println (md5.getStringDigest()) ;
    }

}
