lib/libcrypto/rsa/rsa_pss.c

   1 /* $OpenBSD: rsa_pss.c,v 1.12 2017/01/29 17:49:23 beck 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 (memcmp(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 }