1 /* $OpenBSD: rsa_pss.c,v 1.14 2021/12/12 21:30:14 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 71 static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 }; 72 73 int 74 RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash, const EVP_MD *Hash, 75 const unsigned char *EM, int sLen) 76 { 77 return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen); 78 } 79 80 int 81 RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash, 82 const EVP_MD *Hash, const EVP_MD *mgf1Hash, const unsigned char *EM, 83 int sLen) 84 { 85 int i; 86 int ret = 0; 87 int hLen, maskedDBLen, MSBits, emLen; 88 const unsigned char *H; 89 unsigned char *DB = NULL; 90 EVP_MD_CTX ctx; 91 unsigned char H_[EVP_MAX_MD_SIZE]; 92 93 EVP_MD_CTX_init(&ctx); 94 95 if (mgf1Hash == NULL) 96 mgf1Hash = Hash; 97 98 hLen = EVP_MD_size(Hash); 99 if (hLen < 0) 100 goto err; 101 /* 102 * Negative sLen has special meanings: 103 * -1 sLen == hLen 104 * -2 salt length is autorecovered from signature 105 * -N reserved 106 */ 107 if (sLen == -1) 108 sLen = hLen; 109 else if (sLen == -2) 110 sLen = -2; 111 else if (sLen < -2) { 112 RSAerror(RSA_R_SLEN_CHECK_FAILED); 113 goto err; 114 } 115 116 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 117 emLen = RSA_size(rsa); 118 if (EM[0] & (0xFF << MSBits)) { 119 RSAerror(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 RSAerror(RSA_R_DATA_TOO_LARGE); 129 goto err; 130 } 131 if (EM[emLen - 1] != 0xbc) { 132 RSAerror(RSA_R_LAST_OCTET_INVALID); 133 goto err; 134 } 135 maskedDBLen = emLen - hLen - 1; 136 H = EM + maskedDBLen; 137 DB = malloc(maskedDBLen); 138 if (!DB) { 139 RSAerror(ERR_R_MALLOC_FAILURE); 140 goto err; 141 } 142 if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) 143 goto err; 144 for (i = 0; i < maskedDBLen; i++) 145 DB[i] ^= EM[i]; 146 if (MSBits) 147 DB[0] &= 0xFF >> (8 - MSBits); 148 for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) 149 ; 150 if (DB[i++] != 0x1) { 151 RSAerror(RSA_R_SLEN_RECOVERY_FAILED); 152 goto err; 153 } 154 if (sLen >= 0 && (maskedDBLen - i) != sLen) { 155 RSAerror(RSA_R_SLEN_CHECK_FAILED); 156 goto err; 157 } 158 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 159 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 160 !EVP_DigestUpdate(&ctx, mHash, hLen)) 161 goto err; 162 if (maskedDBLen - i) { 163 if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) 164 goto err; 165 } 166 if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) 167 goto err; 168 if (timingsafe_bcmp(H_, H, hLen)) { 169 RSAerror(RSA_R_BAD_SIGNATURE); 170 ret = 0; 171 } else 172 ret = 1; 173 174 err: 175 free(DB); 176 EVP_MD_CTX_cleanup(&ctx); 177 178 return ret; 179 } 180 181 int 182 RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM, 183 const unsigned char *mHash, const EVP_MD *Hash, int sLen) 184 { 185 return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen); 186 } 187 188 int 189 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, 190 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, 191 int sLen) 192 { 193 int i; 194 int ret = 0; 195 int hLen, maskedDBLen, MSBits, emLen; 196 unsigned char *H, *salt = NULL, *p; 197 EVP_MD_CTX ctx; 198 199 EVP_MD_CTX_init(&ctx); 200 201 if (mgf1Hash == NULL) 202 mgf1Hash = Hash; 203 204 hLen = EVP_MD_size(Hash); 205 if (hLen < 0) 206 goto err; 207 /* 208 * Negative sLen has special meanings: 209 * -1 sLen == hLen 210 * -2 salt length is maximized 211 * -N reserved 212 */ 213 if (sLen == -1) 214 sLen = hLen; 215 else if (sLen == -2) 216 sLen = -2; 217 else if (sLen < -2) { 218 RSAerror(RSA_R_SLEN_CHECK_FAILED); 219 goto err; 220 } 221 222 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 223 emLen = RSA_size(rsa); 224 if (MSBits == 0) { 225 *EM++ = 0; 226 emLen--; 227 } 228 if (sLen == -2) 229 sLen = emLen - hLen - 2; 230 else if (emLen < (hLen + sLen + 2)) { 231 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 232 goto err; 233 } 234 if (sLen > 0) { 235 salt = malloc(sLen); 236 if (!salt) { 237 RSAerror(ERR_R_MALLOC_FAILURE); 238 goto err; 239 } 240 arc4random_buf(salt, sLen); 241 } 242 maskedDBLen = emLen - hLen - 1; 243 H = EM + maskedDBLen; 244 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) || 245 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) || 246 !EVP_DigestUpdate(&ctx, mHash, hLen)) 247 goto err; 248 if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) 249 goto err; 250 if (!EVP_DigestFinal_ex(&ctx, H, NULL)) 251 goto err; 252 253 /* Generate dbMask in place then perform XOR on it */ 254 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) 255 goto err; 256 257 p = EM; 258 259 /* 260 * Initial PS XORs with all zeroes which is a NOP so just update 261 * pointer. Note from a test above this value is guaranteed to 262 * be non-negative. 263 */ 264 p += emLen - sLen - hLen - 2; 265 *p++ ^= 0x1; 266 if (sLen > 0) { 267 for (i = 0; i < sLen; i++) 268 *p++ ^= salt[i]; 269 } 270 if (MSBits) 271 EM[0] &= 0xFF >> (8 - MSBits); 272 273 /* H is already in place so just set final 0xbc */ 274 EM[emLen - 1] = 0xbc; 275 276 ret = 1; 277 278 err: 279 free(salt); 280 EVP_MD_CTX_cleanup(&ctx); 281 282 return ret; 283 } 284