1 /* $OpenBSD: rsa_pss.c,v 1.10 2014/07/13 12:53:46 miod Exp $ */ 2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL 3 * project 2005. 4 */ 5 /* ==================================================================== 6 * Copyright (c) 2005 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * licensing@OpenSSL.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay@cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh@cryptsoft.com). 56 * 57 */ 58 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 63 #include <openssl/bn.h> 64 #include <openssl/err.h> 65 #include <openssl/evp.h> 66 #include <openssl/rsa.h> 67 #include <openssl/sha.h> 68 69 static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 }; 70 71 int 72 RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash, const EVP_MD *Hash, 73 const unsigned char *EM, int sLen) 74 { 75 return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen); 76 } 77 78 int 79 RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash, 80 const EVP_MD *Hash, const EVP_MD *mgf1Hash, const unsigned char *EM, 81 int sLen) 82 { 83 int i; 84 int ret = 0; 85 int hLen, maskedDBLen, MSBits, emLen; 86 const unsigned char *H; 87 unsigned char *DB = NULL; 88 EVP_MD_CTX ctx; 89 unsigned char H_[EVP_MAX_MD_SIZE]; 90 91 EVP_MD_CTX_init(&ctx); 92 93 if (mgf1Hash == NULL) 94 mgf1Hash = Hash; 95 96 hLen = EVP_MD_size(Hash); 97 if (hLen < 0) 98 goto err; 99 /* 100 * Negative sLen has special meanings: 101 * -1 sLen == hLen 102 * -2 salt length is autorecovered from signature 103 * -N reserved 104 */ 105 if (sLen == -1) 106 sLen = hLen; 107 else if (sLen == -2) 108 sLen = -2; 109 else if (sLen < -2) { 110 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, 111 RSA_R_SLEN_CHECK_FAILED); 112 goto err; 113 } 114 115 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 116 emLen = RSA_size(rsa); 117 if (EM[0] & (0xFF << MSBits)) { 118 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, 119 RSA_R_FIRST_OCTET_INVALID); 120 goto err; 121 } 122 if (MSBits == 0) { 123 EM++; 124 emLen--; 125 } 126 if (emLen < (hLen + sLen + 2)) { 127 /* sLen can be small negative */ 128 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE); 129 goto err; 130 } 131 if (EM[emLen - 1] != 0xbc) { 132 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, 133 RSA_R_LAST_OCTET_INVALID); 134 goto err; 135 } 136 maskedDBLen = emLen - hLen - 1; 137 H = EM + maskedDBLen; 138 DB = malloc(maskedDBLen); 139 if (!DB) { 140 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, ERR_R_MALLOC_FAILURE); 141 goto err; 142 } 143 if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) 144 goto err; 145 for (i = 0; i < maskedDBLen; i++) 146 DB[i] ^= EM[i]; 147 if (MSBits) 148 DB[0] &= 0xFF >> (8 - MSBits); 149 for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) 150 ; 151 if (DB[i++] != 0x1) { 152 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, 153 RSA_R_SLEN_RECOVERY_FAILED); 154 goto err; 155 } 156 if (sLen >= 0 && (maskedDBLen - i) != sLen) { 157 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, 158 RSA_R_SLEN_CHECK_FAILED); 159 goto err; 160 } 161 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 162 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 163 !EVP_DigestUpdate(&ctx, mHash, hLen)) 164 goto err; 165 if (maskedDBLen - i) { 166 if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) 167 goto err; 168 } 169 if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) 170 goto err; 171 if (memcmp(H_, H, hLen)) { 172 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_BAD_SIGNATURE); 173 ret = 0; 174 } else 175 ret = 1; 176 177 err: 178 free(DB); 179 EVP_MD_CTX_cleanup(&ctx); 180 181 return ret; 182 } 183 184 int 185 RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM, 186 const unsigned char *mHash, const EVP_MD *Hash, int sLen) 187 { 188 return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen); 189 } 190 191 int 192 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, 193 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, 194 int sLen) 195 { 196 int i; 197 int ret = 0; 198 int hLen, maskedDBLen, MSBits, emLen; 199 unsigned char *H, *salt = NULL, *p; 200 EVP_MD_CTX ctx; 201 202 EVP_MD_CTX_init(&ctx); 203 204 if (mgf1Hash == NULL) 205 mgf1Hash = Hash; 206 207 hLen = EVP_MD_size(Hash); 208 if (hLen < 0) 209 goto err; 210 /* 211 * Negative sLen has special meanings: 212 * -1 sLen == hLen 213 * -2 salt length is maximized 214 * -N reserved 215 */ 216 if (sLen == -1) 217 sLen = hLen; 218 else if (sLen == -2) 219 sLen = -2; 220 else if (sLen < -2) { 221 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1, 222 RSA_R_SLEN_CHECK_FAILED); 223 goto err; 224 } 225 226 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 227 emLen = RSA_size(rsa); 228 if (MSBits == 0) { 229 *EM++ = 0; 230 emLen--; 231 } 232 if (sLen == -2) 233 sLen = emLen - hLen - 2; 234 else if (emLen < (hLen + sLen + 2)) { 235 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1, 236 RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 237 goto err; 238 } 239 if (sLen > 0) { 240 salt = malloc(sLen); 241 if (!salt) { 242 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1, 243 ERR_R_MALLOC_FAILURE); 244 goto err; 245 } 246 arc4random_buf(salt, sLen); 247 } 248 maskedDBLen = emLen - hLen - 1; 249 H = EM + maskedDBLen; 250 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 251 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 252 !EVP_DigestUpdate(&ctx, mHash, hLen)) 253 goto err; 254 if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) 255 goto err; 256 if (!EVP_DigestFinal_ex(&ctx, H, NULL)) 257 goto err; 258 259 /* Generate dbMask in place then perform XOR on it */ 260 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) 261 goto err; 262 263 p = EM; 264 265 /* 266 * Initial PS XORs with all zeroes which is a NOP so just update 267 * pointer. Note from a test above this value is guaranteed to 268 * be non-negative. 269 */ 270 p += emLen - sLen - hLen - 2; 271 *p++ ^= 0x1; 272 if (sLen > 0) { 273 for (i = 0; i < sLen; i++) 274 *p++ ^= salt[i]; 275 } 276 if (MSBits) 277 EM[0] &= 0xFF >> (8 - MSBits); 278 279 /* H is already in place so just set final 0xbc */ 280 EM[emLen - 1] = 0xbc; 281 282 ret = 1; 283 284 err: 285 free(salt); 286 EVP_MD_CTX_cleanup(&ctx); 287 288 return ret; 289 } 290