1 /* $OpenBSD: rsa_pss.c,v 1.19 2024/03/26 05:26:27 joshua 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 *md_ctx; 93 unsigned char H_[EVP_MAX_MD_SIZE]; 94 95 if ((md_ctx = EVP_MD_CTX_new()) == NULL) 96 goto err; 97 98 if (mgf1Hash == NULL) 99 mgf1Hash = Hash; 100 101 hLen = EVP_MD_size(Hash); 102 if (hLen < 0) 103 goto err; 104 /* 105 * Negative sLen has special meanings: 106 * -1 sLen == hLen 107 * -2 salt length is autorecovered from signature 108 * -N reserved 109 */ 110 if (sLen == -1) 111 sLen = hLen; 112 else if (sLen == -2) 113 sLen = -2; 114 else if (sLen < -2) { 115 RSAerror(RSA_R_SLEN_CHECK_FAILED); 116 goto err; 117 } 118 119 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 120 emLen = RSA_size(rsa); 121 if (EM[0] & (0xFF << MSBits)) { 122 RSAerror(RSA_R_FIRST_OCTET_INVALID); 123 goto err; 124 } 125 if (MSBits == 0) { 126 EM++; 127 emLen--; 128 } 129 if (emLen < (hLen + sLen + 2)) { 130 /* sLen can be small negative */ 131 RSAerror(RSA_R_DATA_TOO_LARGE); 132 goto err; 133 } 134 if (EM[emLen - 1] != 0xbc) { 135 RSAerror(RSA_R_LAST_OCTET_INVALID); 136 goto err; 137 } 138 maskedDBLen = emLen - hLen - 1; 139 H = EM + maskedDBLen; 140 DB = malloc(maskedDBLen); 141 if (!DB) { 142 RSAerror(ERR_R_MALLOC_FAILURE); 143 goto err; 144 } 145 if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0) 146 goto err; 147 for (i = 0; i < maskedDBLen; i++) 148 DB[i] ^= EM[i]; 149 if (MSBits) 150 DB[0] &= 0xFF >> (8 - MSBits); 151 for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) 152 ; 153 if (DB[i++] != 0x1) { 154 RSAerror(RSA_R_SLEN_RECOVERY_FAILED); 155 goto err; 156 } 157 if (sLen >= 0 && (maskedDBLen - i) != sLen) { 158 RSAerror(RSA_R_SLEN_CHECK_FAILED); 159 goto err; 160 } 161 if (!EVP_DigestInit_ex(md_ctx, Hash, NULL) || 162 !EVP_DigestUpdate(md_ctx, zeroes, sizeof zeroes) || 163 !EVP_DigestUpdate(md_ctx, mHash, hLen)) 164 goto err; 165 if (maskedDBLen - i) { 166 if (!EVP_DigestUpdate(md_ctx, DB + i, maskedDBLen - i)) 167 goto err; 168 } 169 if (!EVP_DigestFinal_ex(md_ctx, H_, NULL)) 170 goto err; 171 if (timingsafe_bcmp(H_, H, hLen)) { 172 RSAerror(RSA_R_BAD_SIGNATURE); 173 ret = 0; 174 } else { 175 ret = 1; 176 } 177 178 err: 179 free(DB); 180 EVP_MD_CTX_free(md_ctx); 181 182 return ret; 183 } 184 LCRYPTO_ALIAS(RSA_verify_PKCS1_PSS_mgf1); 185 186 int 187 RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM, 188 const unsigned char *mHash, const EVP_MD *Hash, int sLen) 189 { 190 return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen); 191 } 192 LCRYPTO_ALIAS(RSA_padding_add_PKCS1_PSS); 193 194 int 195 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM, 196 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash, 197 int sLen) 198 { 199 int i; 200 int ret = 0; 201 int hLen, maskedDBLen, MSBits, emLen; 202 unsigned char *H, *salt = NULL, *p; 203 EVP_MD_CTX *md_ctx; 204 205 if ((md_ctx = EVP_MD_CTX_new()) == NULL) 206 goto err; 207 208 if (mgf1Hash == NULL) 209 mgf1Hash = Hash; 210 211 hLen = EVP_MD_size(Hash); 212 if (hLen < 0) 213 goto err; 214 /* 215 * Negative sLen has special meanings: 216 * -1 sLen == hLen 217 * -2 salt length is maximized 218 * -N reserved 219 */ 220 if (sLen == -1) 221 sLen = hLen; 222 else if (sLen == -2) 223 sLen = -2; 224 else if (sLen < -2) { 225 RSAerror(RSA_R_SLEN_CHECK_FAILED); 226 goto err; 227 } 228 229 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7; 230 emLen = RSA_size(rsa); 231 if (MSBits == 0) { 232 *EM++ = 0; 233 emLen--; 234 } 235 if (sLen == -2) 236 sLen = emLen - hLen - 2; 237 else if (emLen < (hLen + sLen + 2)) { 238 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); 239 goto err; 240 } 241 if (sLen > 0) { 242 salt = malloc(sLen); 243 if (!salt) { 244 RSAerror(ERR_R_MALLOC_FAILURE); 245 goto err; 246 } 247 arc4random_buf(salt, sLen); 248 } 249 maskedDBLen = emLen - hLen - 1; 250 H = EM + maskedDBLen; 251 if (!EVP_DigestInit_ex(md_ctx, Hash, NULL) || 252 !EVP_DigestUpdate(md_ctx, zeroes, sizeof zeroes) || 253 !EVP_DigestUpdate(md_ctx, mHash, hLen)) 254 goto err; 255 if (sLen && !EVP_DigestUpdate(md_ctx, salt, sLen)) 256 goto err; 257 if (!EVP_DigestFinal_ex(md_ctx, H, NULL)) 258 goto err; 259 260 /* Generate dbMask in place then perform XOR on it */ 261 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) 262 goto err; 263 264 p = EM; 265 266 /* 267 * Initial PS XORs with all zeroes which is a NOP so just update 268 * pointer. Note from a test above this value is guaranteed to 269 * be non-negative. 270 */ 271 p += emLen - sLen - hLen - 2; 272 *p++ ^= 0x1; 273 if (sLen > 0) { 274 for (i = 0; i < sLen; i++) 275 *p++ ^= salt[i]; 276 } 277 if (MSBits) 278 EM[0] &= 0xFF >> (8 - MSBits); 279 280 /* H is already in place so just set final 0xbc */ 281 EM[emLen - 1] = 0xbc; 282 283 ret = 1; 284 285 err: 286 free(salt); 287 EVP_MD_CTX_free(md_ctx); 288 289 return ret; 290 } 291 LCRYPTO_ALIAS(RSA_padding_add_PKCS1_PSS_mgf1); 292