lib/libcrypto/rsa/rsa_sign.c

   1 /* $OpenBSD: rsa_sign.c,v 1.29 2017/05/02 03:59:45 deraadt Exp $ */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include <stdio.h>
  60 #include <string.h>
  61
  62 #include <openssl/bn.h>
  63 #include <openssl/err.h>
  64 #include <openssl/objects.h>
  65 #include <openssl/rsa.h>
  66 #include <openssl/x509.h>
  67
  68 #include "rsa_locl.h"
  69
  70 /* Size of an SSL signature: MD5+SHA1 */
  71 #define SSL_SIG_LENGTH  36
  72
  73 int
  74 RSA_sign(int type, const unsigned char *m, unsigned int m_len,
  75     unsigned char *sigret, unsigned int *siglen, RSA *rsa)
  76 {
  77         X509_SIG sig;
  78         ASN1_TYPE parameter;
  79         int i, j, ret = 1;
  80         unsigned char *p, *tmps = NULL;
  81         const unsigned char *s = NULL;
  82         X509_ALGOR algor;
  83         ASN1_OCTET_STRING digest;
  84
  85         if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_sign)
  86                 return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
  87
  88         /* Special case: SSL signature, just check the length */
  89         if (type == NID_md5_sha1) {
  90                 if (m_len != SSL_SIG_LENGTH) {
  91                         RSAerror(RSA_R_INVALID_MESSAGE_LENGTH);
  92                         return 0;
  93                 }
  94                 i = SSL_SIG_LENGTH;
  95                 s = m;
  96         } else {
  97                 sig.algor = &algor;
  98                 sig.algor->algorithm = OBJ_nid2obj(type);
  99                 if (sig.algor->algorithm == NULL) {
 100                         RSAerror(RSA_R_UNKNOWN_ALGORITHM_TYPE);
 101                         return 0;
 102                 }
 103                 if (sig.algor->algorithm->length == 0) {
 104                         RSAerror(RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
 105                         return 0;
 106                 }
 107                 parameter.type = V_ASN1_NULL;
 108                 parameter.value.ptr = NULL;
 109                 sig.algor->parameter = &parameter;
 110
 111                 sig.digest = &digest;
 112                 sig.digest->data = (unsigned char *)m; /* TMP UGLY CAST */
 113                 sig.digest->length = m_len;
 114
 115                 i = i2d_X509_SIG(&sig, NULL);
 116         }
 117         j = RSA_size(rsa);
 118         if (i > j - RSA_PKCS1_PADDING_SIZE) {
 119                 RSAerror(RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
 120                 return 0;
 121         }
 122         if (type != NID_md5_sha1) {
 123                 tmps = malloc(j + 1);
 124                 if (tmps == NULL) {
 125                         RSAerror(ERR_R_MALLOC_FAILURE);
 126                         return 0;
 127                 }
 128                 p = tmps;
 129                 i2d_X509_SIG(&sig, &p);
 130                 s = tmps;
 131         }
 132         i = RSA_private_encrypt(i, s, sigret, rsa, RSA_PKCS1_PADDING);
 133         if (i <= 0)
 134                 ret = 0;
 135         else
 136                 *siglen = i;
 137
 138         if (type != NID_md5_sha1)
 139                 freezero(tmps, (unsigned int)j + 1);
 140         return (ret);
 141 }
 142
 143 int
 144 int_rsa_verify(int dtype, const unsigned char *m, unsigned int m_len,
 145     unsigned char *rm, size_t *prm_len, const unsigned char *sigbuf,
 146     size_t siglen, RSA *rsa)
 147 {
 148         int i, ret = 0, sigtype;
 149         unsigned char *s;
 150         X509_SIG *sig = NULL;
 151
 152         if (siglen != (unsigned int)RSA_size(rsa)) {
 153                 RSAerror(RSA_R_WRONG_SIGNATURE_LENGTH);
 154                 return 0;
 155         }
 156
 157         if ((dtype == NID_md5_sha1) && rm) {
 158                 i = RSA_public_decrypt((int)siglen, sigbuf, rm, rsa,
 159                     RSA_PKCS1_PADDING);
 160                 if (i <= 0)
 161                         return 0;
 162                 *prm_len = i;
 163                 return 1;
 164         }
 165
 166         s = malloc(siglen);
 167         if (s == NULL) {
 168                 RSAerror(ERR_R_MALLOC_FAILURE);
 169                 goto err;
 170         }
 171         if (dtype == NID_md5_sha1 && m_len != SSL_SIG_LENGTH) {
 172                 RSAerror(RSA_R_INVALID_MESSAGE_LENGTH);
 173                 goto err;
 174         }
 175         i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING);
 176
 177         if (i <= 0)
 178                 goto err;
 179
 180         /* Special case: SSL signature */
 181         if (dtype == NID_md5_sha1) {
 182                 if (i != SSL_SIG_LENGTH || memcmp(s, m, SSL_SIG_LENGTH))
 183                         RSAerror(RSA_R_BAD_SIGNATURE);
 184                 else
 185                         ret = 1;
 186         } else {
 187                 const unsigned char *p = s;
 188
 189                 sig = d2i_X509_SIG(NULL, &p, (long)i);
 190
 191                 if (sig == NULL)
 192                         goto err;
 193
 194                 /* Excess data can be used to create forgeries */
 195                 if (p != s + i) {
 196                         RSAerror(RSA_R_BAD_SIGNATURE);
 197                         goto err;
 198                 }
 199
 200                 /* Parameters to the signature algorithm can also be used to
 201                    create forgeries */
 202                 if (sig->algor->parameter &&
 203                     ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) {
 204                         RSAerror(RSA_R_BAD_SIGNATURE);
 205                         goto err;
 206                 }
 207
 208                 sigtype = OBJ_obj2nid(sig->algor->algorithm);
 209
 210                 if (sigtype != dtype) {
 211                         RSAerror(RSA_R_ALGORITHM_MISMATCH);
 212                         goto err;
 213                 }
 214                 if (rm) {
 215                         const EVP_MD *md;
 216
 217                         md = EVP_get_digestbynid(dtype);
 218                         if (md && (EVP_MD_size(md) != sig->digest->length))
 219                                 RSAerror(RSA_R_INVALID_DIGEST_LENGTH);
 220                         else {
 221                                 memcpy(rm, sig->digest->data,
 222                                     sig->digest->length);
 223                                 *prm_len = sig->digest->length;
 224                                 ret = 1;
 225                         }
 226                 } else if ((unsigned int)sig->digest->length != m_len ||
 227                     memcmp(m, sig->digest->data, m_len) != 0) {
 228                         RSAerror(RSA_R_BAD_SIGNATURE);
 229                 } else
 230                         ret = 1;
 231         }
 232 err:
 233         X509_SIG_free(sig);
 234         freezero(s, (unsigned int)siglen);
 235         return ret;
 236 }
 237
 238 int
 239 RSA_verify(int dtype, const unsigned char *m, unsigned int m_len,
 240     const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
 241 {
 242         if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify)
 243                 return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen,
 244                     rsa);
 245
 246         return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
 247 }