1 /* $OpenBSD: rsa_pss.c,v 1.13 2018/09/05 00:55:33 djm 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 RSAerror(RSA_R_SLEN_CHECK_FAILED); 111 goto err; 112 } 113 114 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 115 emLen = RSA_size(rsa); 116 if (EM[0] & (0xFF << MSBits)) { 117 RSAerror(RSA_R_FIRST_OCTET_INVALID); 118 goto err; 119 } 120 if (MSBits == 0) { 121 EM++; 122 emLen--; 123 } 124 if (emLen < (hLen + sLen + 2)) { 125 /* sLen can be small negative */ 126 RSAerror(RSA_R_DATA_TOO_LARGE); 127 goto err; 128 } 129 if (EM[emLen - 1] != 0xbc) { 130 RSAerror(RSA_R_LAST_OCTET_INVALID); 131 goto err; 132 } 133 maskedDBLen = emLen - hLen - 1; 134 H = EM + maskedDBLen; 135 DB = malloc(maskedDBLen); 136 if (!DB) { 137 RSAerror(ERR_R_MALLOC_FAILURE); 138 goto err; 139 } 140 if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) 141 goto err; 142 for (i = 0; i < maskedDBLen; i++) 143 DB[i] ^= EM[i]; 144 if (MSBits) 145 DB[0] &= 0xFF >> (8 - MSBits); 146 for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) 147 ; 148 if (DB[i++] != 0x1) { 149 RSAerror(RSA_R_SLEN_RECOVERY_FAILED); 150 goto err; 151 } 152 if (sLen >= 0 && (maskedDBLen - i) != sLen) { 153 RSAerror(RSA_R_SLEN_CHECK_FAILED); 154 goto err; 155 } 156 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 157 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 158 !EVP_DigestUpdate(&ctx, mHash, hLen)) 159 goto err; 160 if (maskedDBLen - i) { 161 if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) 162 goto err; 163 } 164 if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) 165 goto err; 166 if (timingsafe_bcmp(H_, H, hLen)) { 167 RSAerror(RSA_R_BAD_SIGNATURE); 168 ret = 0; 169 } else 170 ret = 1; 171 172 err: 173 free(DB); 174 EVP_MD_CTX_cleanup(&ctx); 175 176 return ret; 177 } 178 179 int 180 RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM, 181 const unsigned char *mHash, const EVP_MD *Hash, int sLen) 182 { 183 return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen); 184 } 185 186 int 187 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, 188 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, 189 int sLen) 190 { 191 int i; 192 int ret = 0; 193 int hLen, maskedDBLen, MSBits, emLen; 194 unsigned char *H, *salt = NULL, *p; 195 EVP_MD_CTX ctx; 196 197 EVP_MD_CTX_init(&ctx); 198 199 if (mgf1Hash == NULL) 200 mgf1Hash = Hash; 201 202 hLen = EVP_MD_size(Hash); 203 if (hLen < 0) 204 goto err; 205 /* 206 * Negative sLen has special meanings: 207 * -1 sLen == hLen 208 * -2 salt length is maximized 209 * -N reserved 210 */ 211 if (sLen == -1) 212 sLen = hLen; 213 else if (sLen == -2) 214 sLen = -2; 215 else if (sLen < -2) { 216 RSAerror(RSA_R_SLEN_CHECK_FAILED); 217 goto err; 218 } 219 220 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 221 emLen = RSA_size(rsa); 222 if (MSBits == 0) { 223 *EM++ = 0; 224 emLen--; 225 } 226 if (sLen == -2) 227 sLen = emLen - hLen - 2; 228 else if (emLen < (hLen + sLen + 2)) { 229 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 230 goto err; 231 } 232 if (sLen > 0) { 233 salt = malloc(sLen); 234 if (!salt) { 235 RSAerror(ERR_R_MALLOC_FAILURE); 236 goto err; 237 } 238 arc4random_buf(salt, sLen); 239 } 240 maskedDBLen = emLen - hLen - 1; 241 H = EM + maskedDBLen; 242 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 243 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 244 !EVP_DigestUpdate(&ctx, mHash, hLen)) 245 goto err; 246 if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) 247 goto err; 248 if (!EVP_DigestFinal_ex(&ctx, H, NULL)) 249 goto err; 250 251 /* Generate dbMask in place then perform XOR on it */ 252 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) 253 goto err; 254 255 p = EM; 256 257 /* 258 * Initial PS XORs with all zeroes which is a NOP so just update 259 * pointer. Note from a test above this value is guaranteed to 260 * be non-negative. 261 */ 262 p += emLen - sLen - hLen - 2; 263 *p++ ^= 0x1; 264 if (sLen > 0) { 265 for (i = 0; i < sLen; i++) 266 *p++ ^= salt[i]; 267 } 268 if (MSBits) 269 EM[0] &= 0xFF >> (8 - MSBits); 270 271 /* H is already in place so just set final 0xbc */ 272 EM[emLen - 1] = 0xbc; 273 274 ret = 1; 275 276 err: 277 free(salt); 278 EVP_MD_CTX_cleanup(&ctx); 279 280 return ret; 281 } 282