1 /* $OpenBSD: rsa_pss.c,v 1.15 2022/01/07 09:55:32 tb 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 #include "evp_locl.h" 70 #include "rsa_locl.h" 71 72 static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 }; 73 74 int 75 RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash, const EVP_MD *Hash, 76 const unsigned char *EM, int sLen) 77 { 78 return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen); 79 } 80 81 int 82 RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash, 83 const EVP_MD *Hash, const EVP_MD *mgf1Hash, const unsigned char *EM, 84 int sLen) 85 { 86 int i; 87 int ret = 0; 88 int hLen, maskedDBLen, MSBits, emLen; 89 const unsigned char *H; 90 unsigned char *DB = NULL; 91 EVP_MD_CTX ctx; 92 unsigned char H_[EVP_MAX_MD_SIZE]; 93 94 EVP_MD_CTX_init(&ctx); 95 96 if (mgf1Hash == NULL) 97 mgf1Hash = Hash; 98 99 hLen = EVP_MD_size(Hash); 100 if (hLen < 0) 101 goto err; 102 /* 103 * Negative sLen has special meanings: 104 * -1 sLen == hLen 105 * -2 salt length is autorecovered from signature 106 * -N reserved 107 */ 108 if (sLen == -1) 109 sLen = hLen; 110 else if (sLen == -2) 111 sLen = -2; 112 else if (sLen < -2) { 113 RSAerror(RSA_R_SLEN_CHECK_FAILED); 114 goto err; 115 } 116 117 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 118 emLen = RSA_size(rsa); 119 if (EM[0] & (0xFF << MSBits)) { 120 RSAerror(RSA_R_FIRST_OCTET_INVALID); 121 goto err; 122 } 123 if (MSBits == 0) { 124 EM++; 125 emLen--; 126 } 127 if (emLen < (hLen + sLen + 2)) { 128 /* sLen can be small negative */ 129 RSAerror(RSA_R_DATA_TOO_LARGE); 130 goto err; 131 } 132 if (EM[emLen - 1] != 0xbc) { 133 RSAerror(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 RSAerror(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 RSAerror(RSA_R_SLEN_RECOVERY_FAILED); 153 goto err; 154 } 155 if (sLen >= 0 && (maskedDBLen - i) != sLen) { 156 RSAerror(RSA_R_SLEN_CHECK_FAILED); 157 goto err; 158 } 159 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 160 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 161 !EVP_DigestUpdate(&ctx, mHash, hLen)) 162 goto err; 163 if (maskedDBLen - i) { 164 if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) 165 goto err; 166 } 167 if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) 168 goto err; 169 if (timingsafe_bcmp(H_, H, hLen)) { 170 RSAerror(RSA_R_BAD_SIGNATURE); 171 ret = 0; 172 } else 173 ret = 1; 174 175 err: 176 free(DB); 177 EVP_MD_CTX_cleanup(&ctx); 178 179 return ret; 180 } 181 182 int 183 RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM, 184 const unsigned char *mHash, const EVP_MD *Hash, int sLen) 185 { 186 return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen); 187 } 188 189 int 190 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, 191 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, 192 int sLen) 193 { 194 int i; 195 int ret = 0; 196 int hLen, maskedDBLen, MSBits, emLen; 197 unsigned char *H, *salt = NULL, *p; 198 EVP_MD_CTX ctx; 199 200 EVP_MD_CTX_init(&ctx); 201 202 if (mgf1Hash == NULL) 203 mgf1Hash = Hash; 204 205 hLen = EVP_MD_size(Hash); 206 if (hLen < 0) 207 goto err; 208 /* 209 * Negative sLen has special meanings: 210 * -1 sLen == hLen 211 * -2 salt length is maximized 212 * -N reserved 213 */ 214 if (sLen == -1) 215 sLen = hLen; 216 else if (sLen == -2) 217 sLen = -2; 218 else if (sLen < -2) { 219 RSAerror(RSA_R_SLEN_CHECK_FAILED); 220 goto err; 221 } 222 223 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 224 emLen = RSA_size(rsa); 225 if (MSBits == 0) { 226 *EM++ = 0; 227 emLen--; 228 } 229 if (sLen == -2) 230 sLen = emLen - hLen - 2; 231 else if (emLen < (hLen + sLen + 2)) { 232 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 233 goto err; 234 } 235 if (sLen > 0) { 236 salt = malloc(sLen); 237 if (!salt) { 238 RSAerror(ERR_R_MALLOC_FAILURE); 239 goto err; 240 } 241 arc4random_buf(salt, sLen); 242 } 243 maskedDBLen = emLen - hLen - 1; 244 H = EM + maskedDBLen; 245 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 246 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 247 !EVP_DigestUpdate(&ctx, mHash, hLen)) 248 goto err; 249 if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) 250 goto err; 251 if (!EVP_DigestFinal_ex(&ctx, H, NULL)) 252 goto err; 253 254 /* Generate dbMask in place then perform XOR on it */ 255 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) 256 goto err; 257 258 p = EM; 259 260 /* 261 * Initial PS XORs with all zeroes which is a NOP so just update 262 * pointer. Note from a test above this value is guaranteed to 263 * be non-negative. 264 */ 265 p += emLen - sLen - hLen - 2; 266 *p++ ^= 0x1; 267 if (sLen > 0) { 268 for (i = 0; i < sLen; i++) 269 *p++ ^= salt[i]; 270 } 271 if (MSBits) 272 EM[0] &= 0xFF >> (8 - MSBits); 273 274 /* H is already in place so just set final 0xbc */ 275 EM[emLen - 1] = 0xbc; 276 277 ret = 1; 278 279 err: 280 free(salt); 281 EVP_MD_CTX_cleanup(&ctx); 282 283 return ret; 284 } 285