crypto/rsa/rsa_sign.c

   1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   2  * All rights reserved.
   3  *
   4  * This package is an SSL implementation written
   5  * by Eric Young (eay@cryptsoft.com).
   6  * The implementation was written so as to conform with Netscapes SSL.
   7  *
   8  * This library is free for commercial and non-commercial use as long as
   9  * the following conditions are aheared to.  The following conditions
  10  * apply to all code found in this distribution, be it the RC4, RSA,
  11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  12  * included with this distribution is covered by the same copyright terms
  13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  14  *
  15  * Copyright remains Eric Young's, and as such any Copyright notices in
  16  * the code are not to be removed.
  17  * If this package is used in a product, Eric Young should be given attribution
  18  * as the author of the parts of the library used.
  19  * This can be in the form of a textual message at program startup or
  20  * in documentation (online or textual) provided with the package.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  * 3. All advertising materials mentioning features or use of this software
  31  *    must display the following acknowledgement:
  32  *    "This product includes cryptographic software written by
  33  *     Eric Young (eay@cryptsoft.com)"
  34  *    The word 'cryptographic' can be left out if the rouines from the library
  35  *    being used are not cryptographic related :-).
  36  * 4. If you include any Windows specific code (or a derivative thereof) from
  37  *    the apps directory (application code) you must include an acknowledgement:
  38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50  * SUCH DAMAGE.
  51  *
  52  * The licence and distribution terms for any publically available version or
  53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  54  * copied and put under another distribution licence
  55  * [including the GNU Public Licence.]
  56  */
  57
  58 #include <stdio.h>
  59 #include "internal/cryptlib.h"
  60 #include <openssl/bn.h>
  61 #include <openssl/rsa.h>
  62 #include <openssl/objects.h>
  63 #include <openssl/x509.h>
  64 #include "rsa_locl.h"
  65
  66 /* Size of an SSL signature: MD5+SHA1 */
  67 #define SSL_SIG_LENGTH  36
  68
  69 int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
  70              unsigned char *sigret, unsigned int *siglen, RSA *rsa)
  71 {
  72     X509_SIG sig;
  73     ASN1_TYPE parameter;
  74     int i, j, ret = 1;
  75     unsigned char *p, *tmps = NULL;
  76     const unsigned char *s = NULL;
  77     X509_ALGOR algor;
  78     ASN1_OCTET_STRING digest;
  79     if (rsa->meth->rsa_sign) {
  80         return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
  81     }
  82     /* Special case: SSL signature, just check the length */
  83     if (type == NID_md5_sha1) {
  84         if (m_len != SSL_SIG_LENGTH) {
  85             RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);
  86             return (0);
  87         }
  88         i = SSL_SIG_LENGTH;
  89         s = m;
  90     } else {
  91         sig.algor = &algor;
  92         sig.algor->algorithm = OBJ_nid2obj(type);
  93         if (sig.algor->algorithm == NULL) {
  94             RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
  95             return (0);
  96         }
  97         if (OBJ_length(sig.algor->algorithm) == 0) {
  98             RSAerr(RSA_F_RSA_SIGN,
  99                    RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
 100             return (0);
 101         }
 102         parameter.type = V_ASN1_NULL;
 103         parameter.value.ptr = NULL;
 104         sig.algor->parameter = &parameter;
 105
 106         sig.digest = &digest;
 107         sig.digest->data = (unsigned char *)m; /* TMP UGLY CAST */
 108         sig.digest->length = m_len;
 109
 110         i = i2d_X509_SIG(&sig, NULL);
 111     }
 112     j = RSA_size(rsa);
 113     if (i > (j - RSA_PKCS1_PADDING_SIZE)) {
 114         RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
 115         return (0);
 116     }
 117     if (type != NID_md5_sha1) {
 118         tmps = OPENSSL_malloc((unsigned int)j + 1);
 119         if (tmps == NULL) {
 120             RSAerr(RSA_F_RSA_SIGN, ERR_R_MALLOC_FAILURE);
 121             return (0);
 122         }
 123         p = tmps;
 124         i2d_X509_SIG(&sig, &p);
 125         s = tmps;
 126     }
 127     i = RSA_private_encrypt(i, s, sigret, rsa, RSA_PKCS1_PADDING);
 128     if (i <= 0)
 129         ret = 0;
 130     else
 131         *siglen = i;
 132
 133     if (type != NID_md5_sha1)
 134         OPENSSL_clear_free(tmps, (unsigned int)j + 1);
 135     return (ret);
 136 }
 137
 138 /*
 139  * Check DigestInfo structure does not contain extraneous data by reencoding
 140  * using DER and checking encoding against original.
 141  */
 142 static int rsa_check_digestinfo(X509_SIG *sig, const unsigned char *dinfo,
 143                                 int dinfolen)
 144 {
 145     unsigned char *der = NULL;
 146     int derlen;
 147     int ret = 0;
 148     derlen = i2d_X509_SIG(sig, &der);
 149     if (derlen <= 0)
 150         return 0;
 151     if (derlen == dinfolen && !memcmp(dinfo, der, derlen))
 152         ret = 1;
 153     OPENSSL_clear_free(der, derlen);
 154     return ret;
 155 }
 156
 157 int int_rsa_verify(int dtype, const unsigned char *m,
 158                    unsigned int m_len,
 159                    unsigned char *rm, size_t *prm_len,
 160                    const unsigned char *sigbuf, size_t siglen, RSA *rsa)
 161 {
 162     int i, ret = 0, sigtype;
 163     unsigned char *s;
 164     X509_SIG *sig = NULL;
 165
 166     if (siglen != (unsigned int)RSA_size(rsa)) {
 167         RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH);
 168         return (0);
 169     }
 170
 171     if ((dtype == NID_md5_sha1) && rm) {
 172         i = RSA_public_decrypt((int)siglen,
 173                                sigbuf, rm, rsa, RSA_PKCS1_PADDING);
 174         if (i <= 0)
 175             return 0;
 176         *prm_len = i;
 177         return 1;
 178     }
 179
 180     s = OPENSSL_malloc((unsigned int)siglen);
 181     if (s == NULL) {
 182         RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE);
 183         goto err;
 184     }
 185     if ((dtype == NID_md5_sha1) && (m_len != SSL_SIG_LENGTH)) {
 186         RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
 187         goto err;
 188     }
 189     i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING);
 190
 191     if (i <= 0)
 192         goto err;
 193     /*
 194      * Oddball MDC2 case: signature can be OCTET STRING. check for correct
 195      * tag and length octets.
 196      */
 197     if (dtype == NID_mdc2 && i == 18 && s[0] == 0x04 && s[1] == 0x10) {
 198         if (rm) {
 199             memcpy(rm, s + 2, 16);
 200             *prm_len = 16;
 201             ret = 1;
 202         } else if (memcmp(m, s + 2, 16)) {
 203             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 204         } else {
 205             ret = 1;
 206         }
 207     } else if (dtype == NID_md5_sha1) {
 208         /* Special case: SSL signature */
 209         if ((i != SSL_SIG_LENGTH) || memcmp(s, m, SSL_SIG_LENGTH))
 210             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 211         else
 212             ret = 1;
 213     } else {
 214         const unsigned char *p = s;
 215         sig = d2i_X509_SIG(NULL, &p, (long)i);
 216
 217         if (sig == NULL)
 218             goto err;
 219
 220         /* Excess data can be used to create forgeries */
 221         if (p != s + i || !rsa_check_digestinfo(sig, s, i)) {
 222             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 223             goto err;
 224         }
 225
 226         /*
 227          * Parameters to the signature algorithm can also be used to create
 228          * forgeries
 229          */
 230         if (sig->algor->parameter
 231             && ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) {
 232             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 233             goto err;
 234         }
 235
 236         sigtype = OBJ_obj2nid(sig->algor->algorithm);
 237
 238 #ifdef RSA_DEBUG
 239         /* put a backward compatibility flag in EAY */
 240         fprintf(stderr, "in(%s) expect(%s)\n", OBJ_nid2ln(sigtype),
 241                 OBJ_nid2ln(dtype));
 242 #endif
 243         if (sigtype != dtype) {
 244             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_ALGORITHM_MISMATCH);
 245             goto err;
 246         }
 247         if (rm) {
 248             const EVP_MD *md;
 249             md = EVP_get_digestbynid(dtype);
 250             if (md && (EVP_MD_size(md) != sig->digest->length))
 251                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH);
 252             else {
 253                 memcpy(rm, sig->digest->data, sig->digest->length);
 254                 *prm_len = sig->digest->length;
 255                 ret = 1;
 256             }
 257         } else if (((unsigned int)sig->digest->length != m_len) ||
 258                    (memcmp(m, sig->digest->data, m_len) != 0)) {
 259             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 260         } else
 261             ret = 1;
 262     }
 263  err:
 264     X509_SIG_free(sig);
 265     OPENSSL_clear_free(s, (unsigned int)siglen);
 266     return (ret);
 267 }
 268
 269 int RSA_verify(int dtype, const unsigned char *m, unsigned int m_len,
 270                const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
 271 {
 272
 273     if (rsa->meth->rsa_verify) {
 274         return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen, rsa);
 275     }
 276
 277     return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
 278 }