1 /* $OpenBSD: rsa_pss.c,v 1.18 2024/02/18 15:45:42 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_local.h" 70 #include "rsa_local.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 LCRYPTO_ALIAS(RSA_verify_PKCS1_PSS); 81 82 int 83 RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash, 84 const EVP_MD *Hash, const EVP_MD *mgf1Hash, const unsigned char *EM, 85 int sLen) 86 { 87 int i; 88 int ret = 0; 89 int hLen, maskedDBLen, MSBits, emLen; 90 const unsigned char *H; 91 unsigned char *DB = NULL; 92 EVP_MD_CTX ctx; 93 unsigned char H_[EVP_MAX_MD_SIZE]; 94 95 EVP_MD_CTX_legacy_clear(&ctx); 96 97 if (mgf1Hash == NULL) 98 mgf1Hash = Hash; 99 100 hLen = EVP_MD_size(Hash); 101 if (hLen < 0) 102 goto err; 103 /* 104 * Negative sLen has special meanings: 105 * -1 sLen == hLen 106 * -2 salt length is autorecovered from signature 107 * -N reserved 108 */ 109 if (sLen == -1) 110 sLen = hLen; 111 else if (sLen == -2) 112 sLen = -2; 113 else if (sLen < -2) { 114 RSAerror(RSA_R_SLEN_CHECK_FAILED); 115 goto err; 116 } 117 118 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 119 emLen = RSA_size(rsa); 120 if (EM[0] & (0xFF << MSBits)) { 121 RSAerror(RSA_R_FIRST_OCTET_INVALID); 122 goto err; 123 } 124 if (MSBits == 0) { 125 EM++; 126 emLen--; 127 } 128 if (emLen < (hLen + sLen + 2)) { 129 /* sLen can be small negative */ 130 RSAerror(RSA_R_DATA_TOO_LARGE); 131 goto err; 132 } 133 if (EM[emLen - 1] != 0xbc) { 134 RSAerror(RSA_R_LAST_OCTET_INVALID); 135 goto err; 136 } 137 maskedDBLen = emLen - hLen - 1; 138 H = EM + maskedDBLen; 139 DB = malloc(maskedDBLen); 140 if (!DB) { 141 RSAerror(ERR_R_MALLOC_FAILURE); 142 goto err; 143 } 144 if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) 145 goto err; 146 for (i = 0; i < maskedDBLen; i++) 147 DB[i] ^= EM[i]; 148 if (MSBits) 149 DB[0] &= 0xFF >> (8 - MSBits); 150 for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) 151 ; 152 if (DB[i++] != 0x1) { 153 RSAerror(RSA_R_SLEN_RECOVERY_FAILED); 154 goto err; 155 } 156 if (sLen >= 0 && (maskedDBLen - i) != sLen) { 157 RSAerror(RSA_R_SLEN_CHECK_FAILED); 158 goto err; 159 } 160 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 161 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 162 !EVP_DigestUpdate(&ctx, mHash, hLen)) 163 goto err; 164 if (maskedDBLen - i) { 165 if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) 166 goto err; 167 } 168 if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) 169 goto err; 170 if (timingsafe_bcmp(H_, H, hLen)) { 171 RSAerror(RSA_R_BAD_SIGNATURE); 172 ret = 0; 173 } else 174 ret = 1; 175 176 err: 177 free(DB); 178 EVP_MD_CTX_cleanup(&ctx); 179 180 return ret; 181 } 182 LCRYPTO_ALIAS(RSA_verify_PKCS1_PSS_mgf1); 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 LCRYPTO_ALIAS(RSA_padding_add_PKCS1_PSS); 191 192 int 193 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, 194 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, 195 int sLen) 196 { 197 int i; 198 int ret = 0; 199 int hLen, maskedDBLen, MSBits, emLen; 200 unsigned char *H, *salt = NULL, *p; 201 EVP_MD_CTX ctx; 202 203 EVP_MD_CTX_legacy_clear(&ctx); 204 205 if (mgf1Hash == NULL) 206 mgf1Hash = Hash; 207 208 hLen = EVP_MD_size(Hash); 209 if (hLen < 0) 210 goto err; 211 /* 212 * Negative sLen has special meanings: 213 * -1 sLen == hLen 214 * -2 salt length is maximized 215 * -N reserved 216 */ 217 if (sLen == -1) 218 sLen = hLen; 219 else if (sLen == -2) 220 sLen = -2; 221 else if (sLen < -2) { 222 RSAerror(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 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 236 goto err; 237 } 238 if (sLen > 0) { 239 salt = malloc(sLen); 240 if (!salt) { 241 RSAerror(ERR_R_MALLOC_FAILURE); 242 goto err; 243 } 244 arc4random_buf(salt, sLen); 245 } 246 maskedDBLen = emLen - hLen - 1; 247 H = EM + maskedDBLen; 248 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 249 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 250 !EVP_DigestUpdate(&ctx, mHash, hLen)) 251 goto err; 252 if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) 253 goto err; 254 if (!EVP_DigestFinal_ex(&ctx, H, NULL)) 255 goto err; 256 257 /* Generate dbMask in place then perform XOR on it */ 258 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) 259 goto err; 260 261 p = EM; 262 263 /* 264 * Initial PS XORs with all zeroes which is a NOP so just update 265 * pointer. Note from a test above this value is guaranteed to 266 * be non-negative. 267 */ 268 p += emLen - sLen - hLen - 2; 269 *p++ ^= 0x1; 270 if (sLen > 0) { 271 for (i = 0; i < sLen; i++) 272 *p++ ^= salt[i]; 273 } 274 if (MSBits) 275 EM[0] &= 0xFF >> (8 - MSBits); 276 277 /* H is already in place so just set final 0xbc */ 278 EM[emLen - 1] = 0xbc; 279 280 ret = 1; 281 282 err: 283 free(salt); 284 EVP_MD_CTX_cleanup(&ctx); 285 286 return ret; 287 } 288 LCRYPTO_ALIAS(RSA_padding_add_PKCS1_PSS_mgf1); 289