pkcs1-rsa-md5.c 2.5 KB
Newer Older
Niels Möller's avatar
Niels Möller committed
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
/* pkcs1-rsa-md5.c
 *
 * PKCS stuff for rsa-md5.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2001, 2003 Niels Mller
 *  
 * 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., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#if HAVE_CONFIG_H
27
# include "config.h"
Niels Möller's avatar
Niels Möller committed
28
29
#endif

30
31
32
33
#include <assert.h>
#include <stdlib.h>
#include <string.h>

Niels Möller's avatar
Niels Möller committed
34
35
36
37
38
#include "rsa.h"

#include "bignum.h"
#include "pkcs1.h"

39
40
#include "nettle-internal.h"

Niels Möller's avatar
Niels Möller committed
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
/* From pkcs-1v2
 *
 *   md5 OBJECT IDENTIFIER ::=
 *     {iso(1) member-body(2) US(840) rsadsi(113549) digestAlgorithm(2) 5}
 *
 * The parameters part of the algorithm identifier is NULL:
 *
 *   md5Identifier ::= AlgorithmIdentifier {md5, NULL}
 */

static const uint8_t
md5_prefix[] =
{
  /* 18 octets prefix, 16 octets hash, 34 total. */
  0x30,       32, /* SEQUENCE */
    0x30,     12, /* SEQUENCE */
      0x06,    8, /* OBJECT IDENTIFIER */
  	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05,
      0x05,    0, /* NULL */
    0x04,     16  /* OCTET STRING */
      /* Here comes the raw hash value */
};

void
pkcs1_rsa_md5_encode(mpz_t m, unsigned length, struct md5_ctx *hash)
{
67
68
  TMP_DECL(em, uint8_t, NETTLE_MAX_BIGNUM_BITS / 8);
  TMP_ALLOC(em, length);
Niels Möller's avatar
Niels Möller committed
69
70
71
72
73
74
75
76
77
78
79
80
81

  assert(length >= MD5_DIGEST_SIZE);
  pkcs1_signature_prefix(length - MD5_DIGEST_SIZE, em,
			 sizeof(md5_prefix),
			 md5_prefix);
  
  md5_digest(hash, MD5_DIGEST_SIZE, em + length - MD5_DIGEST_SIZE);
  nettle_mpz_set_str_256_u(m, length, em);
}

void
pkcs1_rsa_md5_encode_digest(mpz_t m, unsigned length, const uint8_t *digest)
{
82
83
  TMP_DECL(em, uint8_t, NETTLE_MAX_BIGNUM_BITS / 8);
  TMP_ALLOC(em, length);
Niels Möller's avatar
Niels Möller committed
84
85
86
87
88
89
90
91
92

  assert(length >= MD5_DIGEST_SIZE);
  pkcs1_signature_prefix(length - MD5_DIGEST_SIZE, em,
			 sizeof(md5_prefix),
			 md5_prefix);

  memcpy(em + length - MD5_DIGEST_SIZE, digest, MD5_DIGEST_SIZE);
  nettle_mpz_set_str_256_u(m, length, em);
}