Implements the MD4 message digest algorithm in Java
// This file is currently unlocked (change this line if you lock the file)
//
// $Log: MD4.java,v $
// Revision 1.2 1998/01/05 03:41:19 iang
// Added references only.
//
// Revision 1.1.1.1 1997/11/03 22:36:56 hopwood
// + Imported to CVS (tagged as 'start').
//
// Revision 0.1.0.0 1997/07/14 R. Naffah
// + original version
//
// $Endlog$
/*
* Copyright (c) 1997 Systemics Ltd
* on behalf of the Cryptix Development Team. All rights reserved.
*/
import java.security.MessageDigest;
/**
* Implements the MD4 message digest algorithm in Java.
* <p>
* <b>References:</b>
* <ol>
* <li> Ronald L. Rivest,
* "<a href="http://www.roxen.com/rfc/rfc1320.html">
* The MD4 Message-Digest Algorithm</a>",
* IETF RFC-1320 (informational).
* </ol>
*
* <p><b>$Revision: 1.2 $</b>
* @author Raif S. Naffah
*/
public class MD4 extends MessageDigest implements Cloneable
{
// MD4 specific object variables
//...........................................................................
/**
* The size in bytes of the input block to the tranformation algorithm.
*/
private static final int BLOCK_LENGTH = 64; // = 512 / 8;
/**
* 4 32-bit words (interim result)
*/
private int[] context = new int[4];
/**
* Number of bytes processed so far mod. 2 power of 64.
*/
private long count;
/**
* 512 bits input buffer = 16 x 32-bit words holds until reaches 512 bits.
*/
private byte[] buffer = new byte[BLOCK_LENGTH];
/**
* 512 bits work buffer = 16 x 32-bit words
*/
private int[] X = new int[16];
// Constructors
//...........................................................................
public MD4 () {
super("MD4");
engineReset();
}
/**
* This constructor is here to implement cloneability of this class.
*/
private MD4 (MD4 md) {
this();
context = (int[])md.context.clone();
buffer = (byte[])md.buffer.clone();
count = md.count;
}
// Cloneable method implementation
//...........................................................................
/**
* Returns a copy of this MD object.
*/
public Object clone() { return new MD4(this); }
// JCE methods
//...........................................................................
/**
* Resets this object disregarding any temporary data present at the
* time of the invocation of this call.
*/
public void engineReset () {
// initial values of MD4 i.e. A, B, C, D
// as per rfc-1320; they are low-order byte first
context[0] = 0x67452301;
context[1] = 0xEFCDAB89;
context[2] = 0x98BADCFE;
context[3] = 0x10325476;
count = 0L;
for (int i = 0; i < BLOCK_LENGTH; i++)
buffer[i] = 0;
}
/**
* Continues an MD4 message digest using the input byte.
*/
public void engineUpdate (byte b) {
// compute number of bytes still unhashed; ie. present in buffer
int i = (int)(count % BLOCK_LENGTH);
count++; // update number of bytes
buffer[i] = b;
if (i == BLOCK_LENGTH - 1)
transform(buffer, 0);
}
/**
* MD4 block update operation.
* <p>
* Continues an MD4 message digest operation, by filling the buffer,
* transform(ing) data in 512-bit message block(s), updating the variables
* context and count, and leaving (buffering) the remaining bytes in buffer
* for the next update or finish.
*
* @param input input block
* @param offset start of meaningful bytes in input
* @param len count of bytes in input block to consider
*/
public void engineUpdate (byte[] input, int offset, int len) {
// make sure we don't exceed input's allocated size/length
if (offset < 0 || len < 0 || (long)offset + len > input.length)
throw new ArrayIndexOutOfBoundsException();
// compute number of bytes still unhashed; ie. present in buffer
int bufferNdx = (int)(count % BLOCK_LENGTH);
count += len; // update number of bytes
int partLen = BLOCK_LENGTH - bufferNdx;
int i = 0;
if (len >= partLen) {
System.arraycopy(input, offset, buffer, bufferNdx, partLen);
transform(buffer, 0);
for (i = partLen; i + BLOCK_LENGTH - 1 < len; i+= BLOCK_LENGTH)
transform(input, offset + i);
bufferNdx = 0;
}
// buffer remaining input
if (i < len)
System.arraycopy(input, offset + i, buffer, bufferNdx, len - i);
}
/**
* Completes the hash computation by performing final operations such
* as padding. At the return of this engineDigest, the MD engine is
* reset.
*
* @return the array of bytes for the resulting hash value.
*/
public byte[] engineDigest () {
// pad output to 56 mod 64; as RFC1320 puts it: congruent to 448 mod 512
int bufferNdx = (int)(count % BLOCK_LENGTH);
int padLen = (bufferNdx < 56) ? (56 - bufferNdx) : (120 - bufferNdx);
// padding is alwas binary 1 followed by binary 0s
byte[] tail = new byte[padLen + 8];
tail[0] = (byte)0x80;
// append length before final transform:
// save number of bits, casting the long to an array of 8 bytes
// save low-order byte first.
for (int i = 0; i < 8; i++)
tail[padLen + i] = (byte)((count * 8) >>> (8 * i));
engineUpdate(tail, 0, tail.length);
byte[] result = new byte[16];
// cast this MD4's context (array of 4 ints) into an array of 16 bytes.
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
result[i * 4 + j] = (byte)(context[i] >>> (8 * j));
// reset the engine
engineReset();
return result;
}
// own methods
//...........................................................................
/**
* MD4 basic transformation.
* <p>
* Transforms context based on 512 bits from input block starting
* from the offset'th byte.
*
* @param block input sub-array.
* @param offset starting position of sub-array.
*/
private void transform (byte[] block, int offset) {
// encodes 64 bytes from input block into an array of 16 32-bit
// entities. Use A as a temp var.
for (int i = 0; i < 16; i++)
X[i] = (block[offset++] & 0xFF) |
(block[offset++] & 0xFF) << 8 |
(block[offset++] & 0xFF) << 16 |
(block[offset++] & 0xFF) << 24;
int A = context[0];
int B = context[1];
int C = context[2];
int D = context[3];
A = FF(A, B, C, D, X[ 0], 3);
D = FF(D, A, B, C, X[ 1], 7);
C = FF(C, D, A, B, X[ 2], 11);
B = FF(B, C, D, A, X[ 3], 19);
A = FF(A, B, C, D, X[ 4], 3);
D = FF(D, A, B, C, X[ 5], 7);
C = FF(C, D, A, B, X[ 6], 11);
B = FF(B, C, D, A, X[ 7], 19);
A = FF(A, B, C, D, X[ 8], 3);
D = FF(D, A, B, C, X[ 9], 7);
C = FF(C, D, A, B, X[10], 11);
B = FF(B, C, D, A, X[11], 19);
A = FF(A, B, C, D, X[12], 3);
D = FF(D, A, B, C, X[13], 7);
C = FF(C, D, A, B, X[14], 11);
B = FF(B, C, D, A, X[15], 19);
A = GG(A, B, C, D, X[ 0], 3);
D = GG(D, A, B, C, X[ 4], 5);
C = GG(C, D, A, B, X[ 8], 9);
B = GG(B, C, D, A, X[12], 13);
A = GG(A, B, C, D, X[ 1], 3);
D = GG(D, A, B, C, X[ 5], 5);
C = GG(C, D, A, B, X[ 9], 9);
B = GG(B, C, D, A, X[13], 13);
A = GG(A, B, C, D, X[ 2], 3);
D = GG(D, A, B, C, X[ 6], 5);
C = GG(C, D, A, B, X[10], 9);
B = GG(B, C, D, A, X[14], 13);
A = GG(A, B, C, D, X[ 3], 3);
D = GG(D, A, B, C, X[ 7], 5);
C = GG(C, D, A, B, X[11], 9);
B = GG(B, C, D, A, X[15], 13);
A = HH(A, B, C, D, X[ 0], 3);
D = HH(D, A, B, C, X[ 8], 9);
C = HH(C, D, A, B, X[ 4], 11);
B = HH(B, C, D, A, X[12], 15);
A = HH(A, B, C, D, X[ 2], 3);
D = HH(D, A, B, C, X[10], 9);
C = HH(C, D, A, B, X[ 6], 11);
B = HH(B, C, D, A, X[14], 15);
A = HH(A, B, C, D, X[ 1], 3);
D = HH(D, A, B, C, X[ 9], 9);
C = HH(C, D, A, B, X[ 5], 11);
B = HH(B, C, D, A, X[13], 15);
A = HH(A, B, C, D, X[ 3], 3);
D = HH(D, A, B, C, X[11], 9);
C = HH(C, D, A, B, X[ 7], 11);
B = HH(B, C, D, A, X[15], 15);
context[0] += A;
context[1] += B;
context[2] += C;
context[3] += D;
}
// The basic MD4 atomic functions.
private int FF (int a, int b, int c, int d, int x, int s) {
int t = a + ((b & c) | (~b & d)) + x;
return t << s | t >>> (32 - s);
}
private int GG (int a, int b, int c, int d, int x, int s) {
int t = a + ((b & (c | d)) | (c & d)) + x + 0x5A827999;
return t << s | t >>> (32 - s);
}
private int HH (int a, int b, int c, int d, int x, int s) {
int t = a + (b ^ c ^ d) + x + 0x6ED9EBA1;
return t << s | t >>> (32 - s);
}
}
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