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crypt-des.c

/* 
   Unix SMB/CIFS implementation.

   a partial implementation of DES designed for use in the 
   SMB authentication protocol

   Copyright (C) Andrew Tridgell 1998

   $Id: crypt-des.c 12116 2004-09-27 23:29:22Z guy $
   
   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 the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <glib.h>

#include <epan/crypt-des.h>

/* NOTES: 

   This code makes no attempt to be fast! In fact, it is a very
   slow implementation 

   This code is NOT a complete DES implementation. It implements only
   the minimum necessary for SMB authentication, as used by all SMB
   products (including every copy of Microsoft Windows95 ever sold)

   In particular, it can only do a unchained forward DES pass. This
   means it is not possible to use this code for encryption/decryption
   of data, instead it is only useful as a "hash" algorithm.

   There is no entry point into this code that allows normal DES operation.

   I believe this means that this code does not come under ITAR
   regulations but this is NOT a legal opinion. If you are concerned
   about the applicability of ITAR regulations to this code then you
   should confirm it for yourself (and maybe let me know if you come
   up with a different answer to the one above)
*/


#define uchar unsigned char

static const uchar perm1[56] = {57, 49, 41, 33, 25, 17,  9,
                   1, 58, 50, 42, 34, 26, 18,
                  10,  2, 59, 51, 43, 35, 27,
                  19, 11,  3, 60, 52, 44, 36,
                  63, 55, 47, 39, 31, 23, 15,
                   7, 62, 54, 46, 38, 30, 22,
                  14,  6, 61, 53, 45, 37, 29,
                  21, 13,  5, 28, 20, 12,  4};

static const uchar perm2[48] = {14, 17, 11, 24,  1,  5,
                         3, 28, 15,  6, 21, 10,
                        23, 19, 12,  4, 26,  8,
                        16,  7, 27, 20, 13,  2,
                        41, 52, 31, 37, 47, 55,
                        30, 40, 51, 45, 33, 48,
                        44, 49, 39, 56, 34, 53,
                        46, 42, 50, 36, 29, 32};

static const uchar perm3[64] = {58, 50, 42, 34, 26, 18, 10,  2,
                  60, 52, 44, 36, 28, 20, 12,  4,
                  62, 54, 46, 38, 30, 22, 14,  6,
                  64, 56, 48, 40, 32, 24, 16,  8,
                  57, 49, 41, 33, 25, 17,  9,  1,
                  59, 51, 43, 35, 27, 19, 11,  3,
                  61, 53, 45, 37, 29, 21, 13,  5,
                  63, 55, 47, 39, 31, 23, 15,  7};

static const uchar perm4[48] = {   32,  1,  2,  3,  4,  5,
                            4,  5,  6,  7,  8,  9,
                            8,  9, 10, 11, 12, 13,
                           12, 13, 14, 15, 16, 17,
                           16, 17, 18, 19, 20, 21,
                           20, 21, 22, 23, 24, 25,
                           24, 25, 26, 27, 28, 29,
                           28, 29, 30, 31, 32,  1};

static const uchar perm5[32] = {      16,  7, 20, 21,
                              29, 12, 28, 17,
                               1, 15, 23, 26,
                               5, 18, 31, 10,
                               2,  8, 24, 14,
                              32, 27,  3,  9,
                              19, 13, 30,  6,
                              22, 11,  4, 25};


static const uchar perm6[64] ={ 40,  8, 48, 16, 56, 24, 64, 32,
                        39,  7, 47, 15, 55, 23, 63, 31,
                        38,  6, 46, 14, 54, 22, 62, 30,
                        37,  5, 45, 13, 53, 21, 61, 29,
                        36,  4, 44, 12, 52, 20, 60, 28,
                        35,  3, 43, 11, 51, 19, 59, 27,
                        34,  2, 42, 10, 50, 18, 58, 26,
                        33,  1, 41,  9, 49, 17, 57, 25};


static const uchar sc[16] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};

static const uchar sbox[8][4][16] = {
      {{14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7},
       {0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8},
       {4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0},
       {15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13}},

      {{15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10},
       {3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5},
       {0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15},
       {13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9}},

      {{10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8},
       {13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1},
       {13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7},
       {1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12}},

      {{7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15},
       {13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9},
       {10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4},
       {3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14}},

      {{2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9},
       {14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6},
       {4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14},
       {11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3}},

      {{12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11},
       {10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8},
       {9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6},
       {4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13}},

      {{4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1},
       {13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6},
       {1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2},
       {6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12}},

      {{13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7},
       {1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2},
       {7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8},
       {2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11}}};

static void permute(char *out, const char *in, const uchar *p, int n)
{
      int i;
      for (i=0;i<n;i++)
            out[i] = in[p[i]-1];
}

static void lshift(char *d, int count, int n)
{
      char out[64];
      int i;
      for (i=0;i<n;i++)
            out[i] = d[(i+count)%n];
      for (i=0;i<n;i++)
            d[i] = out[i];
}

static void concat(char *out, char *in1, char *in2, int l1, int l2)
{
      while (l1--)
            *out++ = *in1++;
      while (l2--)
            *out++ = *in2++;
}

static void xor(char *out, char *in1, char *in2, int n)
{
      int i;
      for (i=0;i<n;i++)
            out[i] = in1[i] ^ in2[i];
}

static void dohash(char *out, char *in, char *key, int forw)
{
      int i, j, k;
      char pk1[56];
      char c[28];
      char d[28];
      char cd[56];
      char ki[16][48];
      char pd1[64];
      char l[32], r[32];
      char rl[64];

      permute(pk1, key, perm1, 56);

      for (i=0;i<28;i++)
            c[i] = pk1[i];
      for (i=0;i<28;i++)
            d[i] = pk1[i+28];

      for (i=0;i<16;i++) {
            lshift(c, sc[i], 28);
            lshift(d, sc[i], 28);

            concat(cd, c, d, 28, 28); 
            permute(ki[i], cd, perm2, 48); 
      }

      permute(pd1, in, perm3, 64);

      for (j=0;j<32;j++) {
            l[j] = pd1[j];
            r[j] = pd1[j+32];
      }

      for (i=0;i<16;i++) {
            char er[48];
            char erk[48];
            char b[8][6];
            char cb[32];
            char pcb[32];
            char r2[32];

            permute(er, r, perm4, 48);

            xor(erk, er, ki[forw ? i : 15 - i], 48);

            for (j=0;j<8;j++)
                  for (k=0;k<6;k++)
                        b[j][k] = erk[j*6 + k];

            for (j=0;j<8;j++) {
                  int m, n;
                  m = (b[j][0]<<1) | b[j][5];

                  n = (b[j][1]<<3) | (b[j][2]<<2) | (b[j][3]<<1) | b[j][4]; 

                  for (k=0;k<4;k++) 
                        b[j][k] = (sbox[j][m][n] & (1<<(3-k)))?1:0; 
            }

            for (j=0;j<8;j++)
                  for (k=0;k<4;k++)
                        cb[j*4+k] = b[j][k];
            permute(pcb, cb, perm5, 32);

            xor(r2, l, pcb, 32);

            for (j=0;j<32;j++)
                  l[j] = r[j];

            for (j=0;j<32;j++)
                  r[j] = r2[j];
      }

      concat(rl, r, l, 32, 32);

      permute(out, rl, perm6, 64);
}

static void str_to_key(const unsigned char *str,unsigned char *key)
{
      int i;

      key[0] = str[0]>>1;
      key[1] = ((str[0]&0x01)<<6) | (str[1]>>2);
      key[2] = ((str[1]&0x03)<<5) | (str[2]>>3);
      key[3] = ((str[2]&0x07)<<4) | (str[3]>>4);
      key[4] = ((str[3]&0x0F)<<3) | (str[4]>>5);
      key[5] = ((str[4]&0x1F)<<2) | (str[5]>>6);
      key[6] = ((str[5]&0x3F)<<1) | (str[6]>>7);
      key[7] = str[6]&0x7F;
      for (i=0;i<8;i++) {
            key[i] = (key[i]<<1);
      }
}


void crypt_des_ecb(unsigned char *out, const unsigned char *in, const unsigned char *key, int forw)
{
      int i;
      char outb[64];
      char inb[64];
      char keyb[64];
      unsigned char key2[8];

      str_to_key(key, key2);

      for (i=0;i<64;i++) {
            inb[i] = (in[i/8] & (1<<(7-(i%8)))) ? 1 : 0;
            keyb[i] = (key2[i/8] & (1<<(7-(i%8)))) ? 1 : 0;
            outb[i] = 0;
      }

      dohash(outb, inb, keyb, forw);

      for (i=0;i<8;i++) {
            out[i] = 0;
      }

      for (i=0;i<64;i++) {
            if (outb[i])
                  out[i/8] |= (1<<(7-(i%8)));
      }
}


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