summaryrefslogtreecommitdiff
path: root/des-compat.c
blob: a74386a5f449c47cb5e9d009497c030fbd33d1d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
/* des-compat.h
 *
 * The des block cipher, libdes/openssl-style interface.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2001 Niels Möller
 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library 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 Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <string.h>
#include <assert.h>

#include "des-compat.h"

#include "cbc.h"
#include "macros.h"
#include "memxor.h"

struct des_compat_des3 { const struct des_ctx *keys[3]; }; 

static void
des_compat_des3_encrypt(struct des_compat_des3 *ctx,
			uint32_t length, uint8_t *dst, const uint8_t *src)
{
  nettle_des_encrypt(ctx->keys[0], length, dst, src);
  nettle_des_decrypt(ctx->keys[1], length, dst, dst);
  nettle_des_encrypt(ctx->keys[2], length, dst, dst);
}

static void
des_compat_des3_decrypt(struct des_compat_des3 *ctx,
			uint32_t length, uint8_t *dst, const uint8_t *src)
{
  nettle_des_decrypt(ctx->keys[2], length, dst, src);
  nettle_des_encrypt(ctx->keys[1], length, dst, dst);
  nettle_des_decrypt(ctx->keys[0], length, dst, dst);
}

void
des_ecb3_encrypt(const_des_cblock *src, des_cblock *dst,
		 des_key_schedule k1,
		 des_key_schedule k2,
		 des_key_schedule k3, int enc)
{
  struct des_compat_des3 keys;
  keys.keys[0] = k1;
  keys.keys[1] = k2;
  keys.keys[2] = k3;

  ((enc == DES_ENCRYPT) ? des_compat_des3_encrypt : des_compat_des3_decrypt)
    (&keys, DES_BLOCK_SIZE, *dst, *src);
}

/* If input is not a integral number of blocks, the final block is
   padded with zeros, no length field or anything like that. That's
   pretty broken, since it means that "$100" and "$100\0" always have
   the same checksum, but I think that's how it's supposed to work. */
uint32_t
des_cbc_cksum(const uint8_t *src, des_cblock *dst,
	      long length, des_key_schedule ctx,
	      const_des_cblock *iv)
{
  /* FIXME: I'm not entirely sure how this function is supposed to
   * work, in particular what it should return, and if iv can be
   * modified. */
  uint8_t block[DES_BLOCK_SIZE];

  memcpy(block, *iv, DES_BLOCK_SIZE);

  while (length >= DES_BLOCK_SIZE)
    {
      memxor(block, src, DES_BLOCK_SIZE);
      nettle_des_encrypt(ctx, DES_BLOCK_SIZE, block, block);

      src += DES_BLOCK_SIZE;
      length -= DES_BLOCK_SIZE;	  
    }
  if (length > 0)
    {
      memxor(block, src, length);
      nettle_des_encrypt(ctx, DES_BLOCK_SIZE, block, block);	  
    }
  memcpy(*dst, block, DES_BLOCK_SIZE);

  return LE_READ_UINT32(block + 4);
}

void
des_ncbc_encrypt(const_des_cblock *src, des_cblock *dst, long length,
                 des_key_schedule ctx, des_cblock *iv,
                 int enc)
{
  switch (enc)
    {
    case DES_ENCRYPT:
      nettle_cbc_encrypt(ctx, (nettle_crypt_func *) des_encrypt,
			 DES_BLOCK_SIZE, *iv,
			 length, *dst, *src);
      break;
    case DES_DECRYPT:
      nettle_cbc_decrypt(ctx,
			 (nettle_crypt_func *) des_decrypt,
			 DES_BLOCK_SIZE, *iv,
			 length, *dst, *src);
      break;
    default:
      abort();
    }
}

void
des_cbc_encrypt(const_des_cblock *src, des_cblock *dst, long length,
		des_key_schedule ctx, const_des_cblock *civ,
		int enc)
{
  des_cblock iv;

  memcpy(iv, civ, DES_BLOCK_SIZE);

  des_ncbc_encrypt(src, dst, length, ctx, &iv, enc);
}


void
des_ecb_encrypt(const_des_cblock *src, des_cblock *dst,
		des_key_schedule ctx,
		int enc)
{
  ((enc == DES_ENCRYPT) ? nettle_des_encrypt : nettle_des_decrypt)
    (ctx, DES_BLOCK_SIZE, *dst, *src);
}

void
des_ede3_cbc_encrypt(const_des_cblock *src, des_cblock *dst, long length,
		     des_key_schedule k1,
		     des_key_schedule k2,
		     des_key_schedule k3,
		     des_cblock *iv,
		     int enc)
{
  struct des_compat_des3 keys;
  keys.keys[0] = k1;
  keys.keys[1] = k2;
  keys.keys[2] = k3;

  switch (enc)
    {
    case DES_ENCRYPT:
      nettle_cbc_encrypt(&keys, (nettle_crypt_func *) des_compat_des3_encrypt,
			 DES_BLOCK_SIZE, *iv,
			 length, *dst, *src);
      break;
    case DES_DECRYPT:
      nettle_cbc_decrypt(&keys, (nettle_crypt_func *) des_compat_des3_decrypt,
			 DES_BLOCK_SIZE, *iv,
			 length, *dst, *src);
      break;
    default:
      abort();
    }
}

int
des_set_odd_parity(des_cblock *key)
{
  nettle_des_fix_parity(DES_KEY_SIZE, *key, *key);

  /* FIXME: What to return? */
  return 0;
}


/* If des_check_key is non-zero, returns
 *
 *   0 for ok, -1 for bad parity, and -2 for weak keys.
 *
 * If des_check_key is zero (the default), always returns zero.
 */

int des_check_key = 0;

int
des_key_sched(const_des_cblock *key, des_key_schedule ctx)
{
  if (des_check_key && !des_check_parity (DES_KEY_SIZE, *key))
    /* Bad parity */
    return -1;
  
  if (!nettle_des_set_key(ctx, *key) && des_check_key)
    /* Weak key */
    return -2;

  return 0;
}

int
des_is_weak_key(const_des_cblock *key)
{
  struct des_ctx ctx;

  return !nettle_des_set_key(&ctx, *key);
}