1 /* $OpenBSD: rsa_sign.c,v 1.26 2017/01/29 17:49:23 beck 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 = ¶meter; 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 explicit_bzero(tmps, (unsigned int)j + 1); 140 free(tmps); 141 } 142 return (ret); 143 } 144 145 int 146 int_rsa_verify(int dtype, const unsigned char *m, unsigned int m_len, 147 unsigned char *rm, size_t *prm_len, const unsigned char *sigbuf, 148 size_t siglen, RSA *rsa) 149 { 150 int i, ret = 0, sigtype; 151 unsigned char *s; 152 X509_SIG *sig = NULL; 153 154 if (siglen != (unsigned int)RSA_size(rsa)) { 155 RSAerror(RSA_R_WRONG_SIGNATURE_LENGTH); 156 return 0; 157 } 158 159 if ((dtype == NID_md5_sha1) && rm) { 160 i = RSA_public_decrypt((int)siglen, sigbuf, rm, rsa, 161 RSA_PKCS1_PADDING); 162 if (i <= 0) 163 return 0; 164 *prm_len = i; 165 return 1; 166 } 167 168 s = malloc(siglen); 169 if (s == NULL) { 170 RSAerror(ERR_R_MALLOC_FAILURE); 171 goto err; 172 } 173 if (dtype == NID_md5_sha1 && m_len != SSL_SIG_LENGTH) { 174 RSAerror(RSA_R_INVALID_MESSAGE_LENGTH); 175 goto err; 176 } 177 i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING); 178 179 if (i <= 0) 180 goto err; 181 182 /* Special case: SSL signature */ 183 if (dtype == NID_md5_sha1) { 184 if (i != SSL_SIG_LENGTH || memcmp(s, m, SSL_SIG_LENGTH)) 185 RSAerror(RSA_R_BAD_SIGNATURE); 186 else 187 ret = 1; 188 } else { 189 const unsigned char *p = s; 190 191 sig = d2i_X509_SIG(NULL, &p, (long)i); 192 193 if (sig == NULL) 194 goto err; 195 196 /* Excess data can be used to create forgeries */ 197 if (p != s + i) { 198 RSAerror(RSA_R_BAD_SIGNATURE); 199 goto err; 200 } 201 202 /* Parameters to the signature algorithm can also be used to 203 create forgeries */ 204 if (sig->algor->parameter && 205 ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) { 206 RSAerror(RSA_R_BAD_SIGNATURE); 207 goto err; 208 } 209 210 sigtype = OBJ_obj2nid(sig->algor->algorithm); 211 212 if (sigtype != dtype) { 213 RSAerror(RSA_R_ALGORITHM_MISMATCH); 214 goto err; 215 } 216 if (rm) { 217 const EVP_MD *md; 218 219 md = EVP_get_digestbynid(dtype); 220 if (md && (EVP_MD_size(md) != sig->digest->length)) 221 RSAerror(RSA_R_INVALID_DIGEST_LENGTH); 222 else { 223 memcpy(rm, sig->digest->data, 224 sig->digest->length); 225 *prm_len = sig->digest->length; 226 ret = 1; 227 } 228 } else if ((unsigned int)sig->digest->length != m_len || 229 memcmp(m, sig->digest->data, m_len) != 0) { 230 RSAerror(RSA_R_BAD_SIGNATURE); 231 } else 232 ret = 1; 233 } 234 err: 235 if (sig != NULL) 236 X509_SIG_free(sig); 237 if (s != NULL) { 238 explicit_bzero(s, (unsigned int)siglen); 239 free(s); 240 } 241 return ret; 242 } 243 244 int 245 RSA_verify(int dtype, const unsigned char *m, unsigned int m_len, 246 const unsigned char *sigbuf, unsigned int siglen, RSA *rsa) 247 { 248 if ((rsa->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify) 249 return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen, 250 rsa); 251 252 return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa); 253 } 254