1/* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11#include "tomcrypt.h"
12
13/**
14  @file rsa_sign_hash.c
15  RSA PKCS #1 v1.5 and v2 PSS sign hash, Tom St Denis and Andreas Lange
16*/
17
18#ifdef MRSA
19
20/**
21  PKCS #1 pad then sign
22  @param in        The hash to sign
23  @param inlen     The length of the hash to sign (octets)
24  @param out       [out] The signature
25  @param outlen    [in/out] The max size and resulting size of the signature
26  @param padding   Type of padding (LTC_PKCS_1_PSS or LTC_PKCS_1_V1_5)
27  @param prng      An active PRNG state
28  @param prng_idx  The index of the PRNG desired
29  @param hash_idx  The index of the hash desired
30  @param saltlen   The length of the salt desired (octets)
31  @param key       The private RSA key to use
32  @return CRYPT_OK if successful
33*/
34int rsa_sign_hash_ex(const unsigned char *in,       unsigned long  inlen,
35                           unsigned char *out,      unsigned long *outlen,
36                           int            padding,
37                           prng_state    *prng,     int            prng_idx,
38                           int            hash_idx, unsigned long  saltlen,
39                           rsa_key *key)
40{
41   unsigned long modulus_bitlen, modulus_bytelen, x, y;
42   int           err;
43
44   LTC_ARGCHK(in       != NULL);
45   LTC_ARGCHK(out      != NULL);
46   LTC_ARGCHK(outlen   != NULL);
47   LTC_ARGCHK(key      != NULL);
48
49   /* valid padding? */
50   if ((padding != LTC_PKCS_1_V1_5) && (padding != LTC_PKCS_1_PSS)) {
51     return CRYPT_PK_INVALID_PADDING;
52   }
53
54   if (padding == LTC_PKCS_1_PSS) {
55     /* valid prng and hash ? */
56     if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
57        return err;
58     }
59     if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
60        return err;
61     }
62   }
63
64   /* get modulus len in bits */
65   modulus_bitlen = mp_count_bits((key->N));
66
67  /* outlen must be at least the size of the modulus */
68  modulus_bytelen = mp_unsigned_bin_size((key->N));
69  if (modulus_bytelen > *outlen) {
70     *outlen = modulus_bytelen;
71     return CRYPT_BUFFER_OVERFLOW;
72  }
73
74  if (padding == LTC_PKCS_1_PSS) {
75    /* PSS pad the key */
76    x = *outlen;
77    if ((err = pkcs_1_pss_encode(in, inlen, saltlen, prng, prng_idx,
78                                 hash_idx, modulus_bitlen, out, &x)) != CRYPT_OK) {
79       return err;
80    }
81  } else {
82    /* PKCS #1 v1.5 pad the hash */
83    unsigned char *tmpin;
84    ltc_asn1_list digestinfo[2], siginfo[2];
85
86    /* not all hashes have OIDs... so sad */
87    if (hash_descriptor[hash_idx].OIDlen == 0) {
88       return CRYPT_INVALID_ARG;
89    }
90
91    /* construct the SEQUENCE
92      SEQUENCE {
93         SEQUENCE {hashoid OID
94                   blah    NULL
95         }
96         hash    OCTET STRING
97      }
98   */
99    LTC_SET_ASN1(digestinfo, 0, LTC_ASN1_OBJECT_IDENTIFIER, hash_descriptor[hash_idx].OID, hash_descriptor[hash_idx].OIDlen);
100    LTC_SET_ASN1(digestinfo, 1, LTC_ASN1_NULL,              NULL,                          0);
101    LTC_SET_ASN1(siginfo,    0, LTC_ASN1_SEQUENCE,          digestinfo,                    2);
102    LTC_SET_ASN1(siginfo,    1, LTC_ASN1_OCTET_STRING,      in,                            inlen);
103
104    /* allocate memory for the encoding */
105    y = mp_unsigned_bin_size(key->N);
106    tmpin = XMALLOC(y);
107    if (tmpin == NULL) {
108       return CRYPT_MEM;
109    }
110
111    if ((err = der_encode_sequence(siginfo, 2, tmpin, &y)) != CRYPT_OK) {
112       XFREE(tmpin);
113       return err;
114    }
115
116    x = *outlen;
117    if ((err = pkcs_1_v1_5_encode(tmpin, y, LTC_PKCS_1_EMSA,
118                                  modulus_bitlen, NULL, 0,
119                                  out, &x)) != CRYPT_OK) {
120      XFREE(tmpin);
121      return err;
122    }
123    XFREE(tmpin);
124  }
125
126  /* RSA encode it */
127  return ltc_mp.rsa_me(out, x, out, outlen, PK_PRIVATE, key);
128}
129
130#endif /* MRSA */
131
132/* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_sign_hash.c,v $ */
133/* $Revision: 1.9 $ */
134/* $Date: 2006/11/09 23:15:39 $ */
135