crypto/rsa/rsa_sign.c

   1 /* crypto/rsa/rsa_sign.c */
   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 "internal/cryptlib.h"
  61 #include <openssl/bn.h>
  62 #include <openssl/rsa.h>
  63 #include <openssl/objects.h>
  64 #include <openssl/x509.h>
  65 #include "rsa_locl.h"
  66
  67 /* Size of an SSL signature: MD5+SHA1 */
  68 #define SSL_SIG_LENGTH  36
  69
  70 int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
  71              unsigned char *sigret, unsigned int *siglen, RSA *rsa)
  72 {
  73     X509_SIG sig;
  74     ASN1_TYPE parameter;
  75     int i, j, ret = 1;
  76     unsigned char *p, *tmps = NULL;
  77     const unsigned char *s = NULL;
  78     X509_ALGOR algor;
  79     ASN1_OCTET_STRING digest;
  80     if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_sign) {
  81         return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
  82     }
  83     /* Special case: SSL signature, just check the length */
  84     if (type == NID_md5_sha1) {
  85         if (m_len != SSL_SIG_LENGTH) {
  86             RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);
  87             return (0);
  88         }
  89         i = SSL_SIG_LENGTH;
  90         s = m;
  91     } else {
  92         sig.algor = &algor;
  93         sig.algor->algorithm = OBJ_nid2obj(type);
  94         if (sig.algor->algorithm == NULL) {
  95             RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
  96             return (0);
  97         }
  98         if (OBJ_length(sig.algor->algorithm) == 0) {
  99             RSAerr(RSA_F_RSA_SIGN,
 100                    RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
 101             return (0);
 102         }
 103         parameter.type = V_ASN1_NULL;
 104         parameter.value.ptr = NULL;
 105         sig.algor->parameter = &parameter;
 106
 107         sig.digest = &digest;
 108         sig.digest->data = (unsigned char *)m; /* TMP UGLY CAST */
 109         sig.digest->length = m_len;
 110
 111         i = i2d_X509_SIG(&sig, NULL);
 112     }
 113     j = RSA_size(rsa);
 114     if (i > (j - RSA_PKCS1_PADDING_SIZE)) {
 115         RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
 116         return (0);
 117     }
 118     if (type != NID_md5_sha1) {
 119         tmps = OPENSSL_malloc((unsigned int)j + 1);
 120         if (tmps == NULL) {
 121             RSAerr(RSA_F_RSA_SIGN, ERR_R_MALLOC_FAILURE);
 122             return (0);
 123         }
 124         p = tmps;
 125         i2d_X509_SIG(&sig, &p);
 126         s = tmps;
 127     }
 128     i = RSA_private_encrypt(i, s, sigret, rsa, RSA_PKCS1_PADDING);
 129     if (i <= 0)
 130         ret = 0;
 131     else
 132         *siglen = i;
 133
 134     if (type != NID_md5_sha1)
 135         OPENSSL_clear_free(tmps, (unsigned int)j + 1);
 136     return (ret);
 137 }
 138
 139 /*
 140  * Check DigestInfo structure does not contain extraneous data by reencoding
 141  * using DER and checking encoding against original.
 142  */
 143 static int rsa_check_digestinfo(X509_SIG *sig, const unsigned char *dinfo,
 144                                 int dinfolen)
 145 {
 146     unsigned char *der = NULL;
 147     int derlen;
 148     int ret = 0;
 149     derlen = i2d_X509_SIG(sig, &der);
 150     if (derlen <= 0)
 151         return 0;
 152     if (derlen == dinfolen && !memcmp(dinfo, der, derlen))
 153         ret = 1;
 154     OPENSSL_clear_free(der, derlen);
 155     return ret;
 156 }
 157
 158 int int_rsa_verify(int dtype, const unsigned char *m,
 159                    unsigned int m_len,
 160                    unsigned char *rm, size_t *prm_len,
 161                    const unsigned char *sigbuf, size_t siglen, RSA *rsa)
 162 {
 163     int i, ret = 0, sigtype;
 164     unsigned char *s;
 165     X509_SIG *sig = NULL;
 166
 167     if (siglen != (unsigned int)RSA_size(rsa)) {
 168         RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH);
 169         return (0);
 170     }
 171
 172     if ((dtype == NID_md5_sha1) && rm) {
 173         i = RSA_public_decrypt((int)siglen,
 174                                sigbuf, rm, rsa, RSA_PKCS1_PADDING);
 175         if (i <= 0)
 176             return 0;
 177         *prm_len = i;
 178         return 1;
 179     }
 180
 181     s = OPENSSL_malloc((unsigned int)siglen);
 182     if (s == NULL) {
 183         RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE);
 184         goto err;
 185     }
 186     if ((dtype == NID_md5_sha1) && (m_len != SSL_SIG_LENGTH)) {
 187         RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
 188         goto err;
 189     }
 190     i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING);
 191
 192     if (i <= 0)
 193         goto err;
 194     /*
 195      * Oddball MDC2 case: signature can be OCTET STRING. check for correct
 196      * tag and length octets.
 197      */
 198     if (dtype == NID_mdc2 && i == 18 && s[0] == 0x04 && s[1] == 0x10) {
 199         if (rm) {
 200             memcpy(rm, s + 2, 16);
 201             *prm_len = 16;
 202             ret = 1;
 203         } else if (memcmp(m, s + 2, 16)) {
 204             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 205         } else {
 206             ret = 1;
 207         }
 208     } else if (dtype == NID_md5_sha1) {
 209         /* Special case: SSL signature */
 210         if ((i != SSL_SIG_LENGTH) || memcmp(s, m, SSL_SIG_LENGTH))
 211             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 212         else
 213             ret = 1;
 214     } else {
 215         const unsigned char *p = s;
 216         sig = d2i_X509_SIG(NULL, &p, (long)i);
 217
 218         if (sig == NULL)
 219             goto err;
 220
 221         /* Excess data can be used to create forgeries */
 222         if (p != s + i || !rsa_check_digestinfo(sig, s, i)) {
 223             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 224             goto err;
 225         }
 226
 227         /*
 228          * Parameters to the signature algorithm can also be used to create
 229          * forgeries
 230          */
 231         if (sig->algor->parameter
 232             && ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) {
 233             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 234             goto err;
 235         }
 236
 237         sigtype = OBJ_obj2nid(sig->algor->algorithm);
 238
 239 #ifdef RSA_DEBUG
 240         /* put a backward compatibility flag in EAY */
 241         fprintf(stderr, "in(%s) expect(%s)\n", OBJ_nid2ln(sigtype),
 242                 OBJ_nid2ln(dtype));
 243 #endif
 244         if (sigtype != dtype) {
 245             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_ALGORITHM_MISMATCH);
 246             goto err;
 247         }
 248         if (rm) {
 249             const EVP_MD *md;
 250             md = EVP_get_digestbynid(dtype);
 251             if (md && (EVP_MD_size(md) != sig->digest->length))
 252                 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH);
 253             else {
 254                 memcpy(rm, sig->digest->data, sig->digest->length);
 255                 *prm_len = sig->digest->length;
 256                 ret = 1;
 257             }
 258         } else if (((unsigned int)sig->digest->length != m_len) ||
 259                    (memcmp(m, sig->digest->data, m_len) != 0)) {
 260             RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
 261         } else
 262             ret = 1;
 263     }
 264  err:
 265     X509_SIG_free(sig);
 266     OPENSSL_clear_free(s, (unsigned int)siglen);
 267     return (ret);
 268 }
 269
 270 int RSA_verify(int dtype, const unsigned char *m, unsigned int m_len,
 271                const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
 272 {
 273
 274     if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify) {
 275         return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen, rsa);
 276     }
 277
 278     return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
 279 }