1 /* $OpenBSD: rsa_sign.c,v 1.24 2015/07/19 18:29:31 miod 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 RSAerr(RSA_F_RSA_SIGN, 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 RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE); 101 return 0; 102 } 103 if (sig.algor->algorithm->length == 0) { 104 RSAerr(RSA_F_RSA_SIGN, 105 RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD); 106 return 0; 107 } 108 parameter.type = V_ASN1_NULL; 109 parameter.value.ptr = NULL; 110 sig.algor->parameter = ¶meter; 111 112 sig.digest = &digest; 113 sig.digest->data = (unsigned char *)m; /* TMP UGLY CAST */ 114 sig.digest->length = m_len; 115 116 i = i2d_X509_SIG(&sig, NULL); 117 } 118 j = RSA_size(rsa); 119 if (i > j - RSA_PKCS1_PADDING_SIZE) { 120 RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY); 121 return 0; 122 } 123 if (type != NID_md5_sha1) { 124 tmps = malloc(j + 1); 125 if (tmps == NULL) { 126 RSAerr(RSA_F_RSA_SIGN, ERR_R_MALLOC_FAILURE); 127 return 0; 128 } 129 p = tmps; 130 i2d_X509_SIG(&sig, &p); 131 s = tmps; 132 } 133 i = RSA_private_encrypt(i, s, sigret, rsa, RSA_PKCS1_PADDING); 134 if (i <= 0) 135 ret = 0; 136 else 137 *siglen = i; 138 139 if (type != NID_md5_sha1) { 140 explicit_bzero(tmps, (unsigned int)j + 1); 141 free(tmps); 142 } 143 return (ret); 144 } 145 146 int 147 int_rsa_verify(int dtype, const unsigned char *m, unsigned int m_len, 148 unsigned char *rm, size_t *prm_len, const unsigned char *sigbuf, 149 size_t siglen, RSA *rsa) 150 { 151 int i, ret = 0, sigtype; 152 unsigned char *s; 153 X509_SIG *sig = NULL; 154 155 if (siglen != (unsigned int)RSA_size(rsa)) { 156 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH); 157 return 0; 158 } 159 160 if ((dtype == NID_md5_sha1) && rm) { 161 i = RSA_public_decrypt((int)siglen, sigbuf, rm, rsa, 162 RSA_PKCS1_PADDING); 163 if (i <= 0) 164 return 0; 165 *prm_len = i; 166 return 1; 167 } 168 169 s = malloc(siglen); 170 if (s == NULL) { 171 RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE); 172 goto err; 173 } 174 if (dtype == NID_md5_sha1 && m_len != SSL_SIG_LENGTH) { 175 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH); 176 goto err; 177 } 178 i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING); 179 180 if (i <= 0) 181 goto err; 182 183 /* Special case: SSL signature */ 184 if (dtype == NID_md5_sha1) { 185 if (i != SSL_SIG_LENGTH || memcmp(s, m, SSL_SIG_LENGTH)) 186 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 187 else 188 ret = 1; 189 } else { 190 const unsigned char *p = s; 191 192 sig = d2i_X509_SIG(NULL, &p, (long)i); 193 194 if (sig == NULL) 195 goto err; 196 197 /* Excess data can be used to create forgeries */ 198 if (p != s + i) { 199 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 200 goto err; 201 } 202 203 /* Parameters to the signature algorithm can also be used to 204 create forgeries */ 205 if (sig->algor->parameter && 206 ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) { 207 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 208 goto err; 209 } 210 211 sigtype = OBJ_obj2nid(sig->algor->algorithm); 212 213 if (sigtype != dtype) { 214 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_ALGORITHM_MISMATCH); 215 goto err; 216 } 217 if (rm) { 218 const EVP_MD *md; 219 220 md = EVP_get_digestbynid(dtype); 221 if (md && (EVP_MD_size(md) != sig->digest->length)) 222 RSAerr(RSA_F_INT_RSA_VERIFY, 223 RSA_R_INVALID_DIGEST_LENGTH); 224 else { 225 memcpy(rm, sig->digest->data, 226 sig->digest->length); 227 *prm_len = sig->digest->length; 228 ret = 1; 229 } 230 } else if ((unsigned int)sig->digest->length != m_len || 231 memcmp(m, sig->digest->data, m_len) != 0) { 232 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 233 } else 234 ret = 1; 235 } 236 err: 237 if (sig != NULL) 238 X509_SIG_free(sig); 239 if (s != NULL) { 240 explicit_bzero(s, (unsigned int)siglen); 241 free(s); 242 } 243 return ret; 244 } 245 246 int 247 RSA_verify(int dtype, const unsigned char *m, unsigned int m_len, 248 const unsigned char *sigbuf, unsigned int siglen, RSA *rsa) 249 { 250 if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify) 251 return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen, 252 rsa); 253 254 return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa); 255 } 256