mdfour.c

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/*
    mdfour.c
 
    An implementation of MD4 designed for use in the samba SMB
    authentication protocol
 
    Copyright (C) 1997-1998  Andrew Tridgell
 
    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.
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to:
 
        Free Software Foundation, Inc.
        59 Temple Place - Suite 330
        Boston, MA  02111-1307, USA
 
    $Id$
*/
 
#include "darkplaces.h"
 
#include "mdfour.h"
 
/* NOTE: This code makes no attempt to be fast!
 
   It assumes that a int is at least 32 bits long
*/
 
#define F(X,Y,Z) (((X)&(Y)) | ((~(X))&(Z)))
#define G(X,Y,Z) (((X)&(Y)) | ((X)&(Z)) | ((Y)&(Z)))
#define H(X,Y,Z) ((X)^(Y)^(Z))
#define lshift(x,s) (((x)<<(s)) | ((x)>>(32-(s))))
 
#define ROUND1(a,b,c,d,k,s) a = lshift(a + F(b,c,d) + X[k], s)
#define ROUND2(a,b,c,d,k,s) a = lshift(a + G(b,c,d) + X[k] + 0x5A827999,s)
#define ROUND3(a,b,c,d,k,s) a = lshift(a + H(b,c,d) + X[k] + 0x6ED9EBA1,s)
 
/* this applies md4 to 64 byte chunks */
static void mdfour64(struct mdfour_s *md, uint32_t *M)
{
    int j;
    uint32_t AA, BB, CC, DD;
    uint32_t X[16];
    uint32_t A,B,C,D;
 
    for (j=0;j<16;j++)
        X[j] = M[j];
 
    A = md->A; B = md->B; C = md->C; D = md->D;
    AA = A; BB = B; CC = C; DD = D;
 
        ROUND1(A,B,C,D,  0,  3);  ROUND1(D,A,B,C,  1,  7);
    ROUND1(C,D,A,B,  2, 11);  ROUND1(B,C,D,A,  3, 19);
        ROUND1(A,B,C,D,  4,  3);  ROUND1(D,A,B,C,  5,  7);
    ROUND1(C,D,A,B,  6, 11);  ROUND1(B,C,D,A,  7, 19);
        ROUND1(A,B,C,D,  8,  3);  ROUND1(D,A,B,C,  9,  7);
    ROUND1(C,D,A,B, 10, 11);  ROUND1(B,C,D,A, 11, 19);
        ROUND1(A,B,C,D, 12,  3);  ROUND1(D,A,B,C, 13,  7);
    ROUND1(C,D,A,B, 14, 11);  ROUND1(B,C,D,A, 15, 19);
 
        ROUND2(A,B,C,D,  0,  3);  ROUND2(D,A,B,C,  4,  5);
    ROUND2(C,D,A,B,  8,  9);  ROUND2(B,C,D,A, 12, 13);
        ROUND2(A,B,C,D,  1,  3);  ROUND2(D,A,B,C,  5,  5);
    ROUND2(C,D,A,B,  9,  9);  ROUND2(B,C,D,A, 13, 13);
        ROUND2(A,B,C,D,  2,  3);  ROUND2(D,A,B,C,  6,  5);
    ROUND2(C,D,A,B, 10,  9);  ROUND2(B,C,D,A, 14, 13);
        ROUND2(A,B,C,D,  3,  3);  ROUND2(D,A,B,C,  7,  5);
    ROUND2(C,D,A,B, 11,  9);  ROUND2(B,C,D,A, 15, 13);
 
    ROUND3(A,B,C,D,  0,  3);  ROUND3(D,A,B,C,  8,  9);
    ROUND3(C,D,A,B,  4, 11);  ROUND3(B,C,D,A, 12, 15);
        ROUND3(A,B,C,D,  2,  3);  ROUND3(D,A,B,C, 10,  9);
    ROUND3(C,D,A,B,  6, 11);  ROUND3(B,C,D,A, 14, 15);
        ROUND3(A,B,C,D,  1,  3);  ROUND3(D,A,B,C,  9,  9);
    ROUND3(C,D,A,B,  5, 11);  ROUND3(B,C,D,A, 13, 15);
        ROUND3(A,B,C,D,  3,  3);  ROUND3(D,A,B,C, 11,  9);
    ROUND3(C,D,A,B,  7, 11);  ROUND3(B,C,D,A, 15, 15);
 
    A += AA; B += BB; C += CC; D += DD;
 
    for (j=0;j<16;j++)
        X[j] = 0;
 
    md->A = A; md->B = B; md->C = C; md->D = D;
}
 
static void copy64(uint32_t *M, const unsigned char *in)
{
    int i;
 
    // UBSan: (unsigned) is because promotion to int causes signed overflow when in[] >= 128
    for (i=0;i<16;i++)
        M[i] = ((unsigned)in[i*4+3]<<24) | (in[i*4+2]<<16) |
            (in[i*4+1]<<8) | (in[i*4+0]<<0);
}
 
static void copy4(unsigned char *out,uint32_t x)
{
    out[0] = x&0xFF;
    out[1] = (x>>8)&0xFF;
    out[2] = (x>>16)&0xFF;
    out[3] = (x>>24)&0xFF;
}
 
void mdfour_begin(struct mdfour_s *md)
{
    md->A = 0x67452301;
    md->B = 0xefcdab89;
    md->C = 0x98badcfe;
    md->D = 0x10325476;
    md->totalN = 0;
}
 
 
static void mdfour_tail(struct mdfour_s *md, const unsigned char *in, int n)
{
    unsigned char buf[128];
    uint32_t M[16];
    uint32_t b;
 
    md->totalN += n;
 
    b = md->totalN * 8;
 
    memset(buf, 0, 128);
    if (n) memcpy(buf, in, n);
    buf[n] = 0x80;
 
    if (n <= 55) {
        copy4(buf+56, b);
        copy64(M, buf);
        mdfour64(md, M);
    } else {
        copy4(buf+120, b);
        copy64(M, buf);
        mdfour64(md, M);
        copy64(M, buf+64);
        mdfour64(md, M);
    }
}
 
void mdfour_update(struct mdfour_s *md, const unsigned char *in, int n)
{
    uint32_t M[16];
 
// start of edit by Ashley Rose Hale (LadyHavoc)
// commented out to prevent crashing when length is 0
//  if (n == 0) mdfour_tail(in, n);
// end of edit by Ashley Rose Hale (LadyHavoc)
 
    while (n >= 64) {
        copy64(M, in);
        mdfour64(md, M);
        in += 64;
        n -= 64;
        md->totalN += 64;
    }
 
    mdfour_tail(md, in, n);
}
 
 
void mdfour_result(struct mdfour_s *md, unsigned char *out)
{
    copy4(out, md->A);
    copy4(out+4, md->B);
    copy4(out+8, md->C);
    copy4(out+12, md->D);
}
 
 
void mdfour(unsigned char *out, const unsigned char *in, int n)
{
    struct mdfour_s md;
    mdfour_begin(&md);
    mdfour_update(&md, in, n);
    mdfour_result(&md, out);
}
 
//  MD4-based checksum utility functions
//
//  Copyright (C) 2000       Jeff Teunissen <d2deek@pmail.net>
//
//  Author: Jeff Teunissen  <d2deek@pmail.net>
//  Date: 01 Jan 2000
 
unsigned Com_BlockChecksum (void *buffer, int length)
{
    int             digest[4];
    unsigned        val;
 
    mdfour ( (unsigned char *) digest, (unsigned char *) buffer, length );
 
    val = digest[0] ^ digest[1] ^ digest[2] ^ digest[3];
 
    return val;
}
 
void Com_BlockFullChecksum (void *buffer, int len, unsigned char *outbuf)
{
    mdfour ( outbuf, (unsigned char *) buffer, len );
}