1 /* 2 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include <stdio.h> 11 #include "internal/cryptlib.h" 12 #include <openssl/bn.h> 13 #include <openssl/rsa.h> 14 #include <openssl/objects.h> 15 #include <openssl/x509.h> 16 #include "crypto/x509.h" 17 #include "rsa_local.h" 18 19 /* Size of an SSL signature: MD5+SHA1 */ 20 #define SSL_SIG_LENGTH 36 21 22 /* 23 * encode_pkcs1 encodes a DigestInfo prefix of hash |type| and digest |m|, as 24 * described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This 25 * encodes the DigestInfo (T and tLen) but does not add the padding. 26 * 27 * On success, it returns one and sets |*out| to a newly allocated buffer 28 * containing the result and |*out_len| to its length. The caller must free 29 * |*out| with |OPENSSL_free|. Otherwise, it returns zero. 30 */ 31 static int encode_pkcs1(unsigned char **out, int *out_len, int type, 32 const unsigned char *m, unsigned int m_len) 33 { 34 X509_SIG sig; 35 X509_ALGOR algor; 36 ASN1_TYPE parameter; 37 ASN1_OCTET_STRING digest; 38 uint8_t *der = NULL; 39 int len; 40 41 sig.algor = &algor; 42 sig.algor->algorithm = OBJ_nid2obj(type); 43 if (sig.algor->algorithm == NULL) { 44 RSAerr(RSA_F_ENCODE_PKCS1, RSA_R_UNKNOWN_ALGORITHM_TYPE); 45 return 0; 46 } 47 if (OBJ_length(sig.algor->algorithm) == 0) { 48 RSAerr(RSA_F_ENCODE_PKCS1, 49 RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD); 50 return 0; 51 } 52 parameter.type = V_ASN1_NULL; 53 parameter.value.ptr = NULL; 54 sig.algor->parameter = ¶meter; 55 56 sig.digest = &digest; 57 sig.digest->data = (unsigned char *)m; 58 sig.digest->length = m_len; 59 60 len = i2d_X509_SIG(&sig, &der); 61 if (len < 0) 62 return 0; 63 64 *out = der; 65 *out_len = len; 66 return 1; 67 } 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 int encrypt_len, encoded_len = 0, ret = 0; 73 unsigned char *tmps = NULL; 74 const unsigned char *encoded = NULL; 75 76 if (rsa->meth->rsa_sign) { 77 return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa); 78 } 79 80 /* Compute the encoded digest. */ 81 if (type == NID_md5_sha1) { 82 /* 83 * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and 84 * earlier. It has no DigestInfo wrapper but otherwise is 85 * RSASSA-PKCS1-v1_5. 86 */ 87 if (m_len != SSL_SIG_LENGTH) { 88 RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH); 89 return 0; 90 } 91 encoded_len = SSL_SIG_LENGTH; 92 encoded = m; 93 } else { 94 if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len)) 95 goto err; 96 encoded = tmps; 97 } 98 99 if (encoded_len > RSA_size(rsa) - RSA_PKCS1_PADDING_SIZE) { 100 RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY); 101 goto err; 102 } 103 encrypt_len = RSA_private_encrypt(encoded_len, encoded, sigret, rsa, 104 RSA_PKCS1_PADDING); 105 if (encrypt_len <= 0) 106 goto err; 107 108 *siglen = encrypt_len; 109 ret = 1; 110 111 err: 112 OPENSSL_clear_free(tmps, (size_t)encoded_len); 113 return ret; 114 } 115 116 /* 117 * int_rsa_verify verifies an RSA signature in |sigbuf| using |rsa|. It may be 118 * called in two modes. If |rm| is NULL, it verifies the signature for digest 119 * |m|. Otherwise, it recovers the digest from the signature, writing the digest 120 * to |rm| and the length to |*prm_len|. |type| is the NID of the digest 121 * algorithm to use. It returns one on successful verification and zero 122 * otherwise. 123 */ 124 int int_rsa_verify(int type, const unsigned char *m, unsigned int m_len, 125 unsigned char *rm, size_t *prm_len, 126 const unsigned char *sigbuf, size_t siglen, RSA *rsa) 127 { 128 int decrypt_len, ret = 0, encoded_len = 0; 129 unsigned char *decrypt_buf = NULL, *encoded = NULL; 130 131 if (siglen != (size_t)RSA_size(rsa)) { 132 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH); 133 return 0; 134 } 135 136 /* Recover the encoded digest. */ 137 decrypt_buf = OPENSSL_malloc(siglen); 138 if (decrypt_buf == NULL) { 139 RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE); 140 goto err; 141 } 142 143 decrypt_len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa, 144 RSA_PKCS1_PADDING); 145 if (decrypt_len <= 0) 146 goto err; 147 148 if (type == NID_md5_sha1) { 149 /* 150 * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and 151 * earlier. It has no DigestInfo wrapper but otherwise is 152 * RSASSA-PKCS1-v1_5. 153 */ 154 if (decrypt_len != SSL_SIG_LENGTH) { 155 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 156 goto err; 157 } 158 159 if (rm != NULL) { 160 memcpy(rm, decrypt_buf, SSL_SIG_LENGTH); 161 *prm_len = SSL_SIG_LENGTH; 162 } else { 163 if (m_len != SSL_SIG_LENGTH) { 164 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH); 165 goto err; 166 } 167 168 if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) { 169 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 170 goto err; 171 } 172 } 173 } else if (type == NID_mdc2 && decrypt_len == 2 + 16 174 && decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) { 175 /* 176 * Oddball MDC2 case: signature can be OCTET STRING. check for correct 177 * tag and length octets. 178 */ 179 if (rm != NULL) { 180 memcpy(rm, decrypt_buf + 2, 16); 181 *prm_len = 16; 182 } else { 183 if (m_len != 16) { 184 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH); 185 goto err; 186 } 187 188 if (memcmp(m, decrypt_buf + 2, 16) != 0) { 189 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 190 goto err; 191 } 192 } 193 } else { 194 /* 195 * If recovering the digest, extract a digest-sized output from the end 196 * of |decrypt_buf| for |encode_pkcs1|, then compare the decryption 197 * output as in a standard verification. 198 */ 199 if (rm != NULL) { 200 const EVP_MD *md = EVP_get_digestbynid(type); 201 if (md == NULL) { 202 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_UNKNOWN_ALGORITHM_TYPE); 203 goto err; 204 } 205 206 m_len = EVP_MD_size(md); 207 if (m_len > (size_t)decrypt_len) { 208 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH); 209 goto err; 210 } 211 m = decrypt_buf + decrypt_len - m_len; 212 } 213 214 /* Construct the encoded digest and ensure it matches. */ 215 if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len)) 216 goto err; 217 218 if (encoded_len != decrypt_len 219 || memcmp(encoded, decrypt_buf, encoded_len) != 0) { 220 RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); 221 goto err; 222 } 223 224 /* Output the recovered digest. */ 225 if (rm != NULL) { 226 memcpy(rm, m, m_len); 227 *prm_len = m_len; 228 } 229 } 230 231 ret = 1; 232 233 err: 234 OPENSSL_clear_free(encoded, (size_t)encoded_len); 235 OPENSSL_clear_free(decrypt_buf, siglen); 236 return ret; 237 } 238 239 int RSA_verify(int type, const unsigned char *m, unsigned int m_len, 240 const unsigned char *sigbuf, unsigned int siglen, RSA *rsa) 241 { 242 243 if (rsa->meth->rsa_verify) { 244 return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa); 245 } 246 247 return int_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa); 248 } 249