crypto/rsa/rsa_pss.c

   1 /*
   2  * Copyright 2005-2017 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/bn.h>
  13 #include <openssl/rsa.h>
  14 #include <openssl/evp.h>
  15 #include <openssl/rand.h>
  16 #include <openssl/sha.h>
  17 #include "rsa_locl.h"
  18
  19 static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
  20
  21 #if defined(_MSC_VER) && defined(_ARM_)
  22 # pragma optimize("g", off)
  23 #endif
  24
  25 int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,
  26                          const EVP_MD *Hash, const unsigned char *EM,
  27                          int sLen)
  28 {
  29     return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen);
  30 }
  31
  32 int RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash,
  33                               const EVP_MD *Hash, const EVP_MD *mgf1Hash,
  34                               const unsigned char *EM, int sLen)
  35 {
  36     int i;
  37     int ret = 0;
  38     int hLen, maskedDBLen, MSBits, emLen;
  39     const unsigned char *H;
  40     unsigned char *DB = NULL;
  41     EVP_MD_CTX *ctx = EVP_MD_CTX_new();
  42     unsigned char H_[EVP_MAX_MD_SIZE];
  43
  44     if (ctx == NULL)
  45         goto err;
  46
  47     if (mgf1Hash == NULL)
  48         mgf1Hash = Hash;
  49
  50     hLen = EVP_MD_size(Hash);
  51     if (hLen < 0)
  52         goto err;
  53     /*-
  54      * Negative sLen has special meanings:
  55      *      -1      sLen == hLen
  56      *      -2      salt length is autorecovered from signature
  57      *      -3      salt length is maximized
  58      *      -N      reserved
  59      */
  60     if (sLen == RSA_PSS_SALTLEN_DIGEST) {
  61         sLen = hLen;
  62     } else if (sLen < RSA_PSS_SALTLEN_MAX) {
  63         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);
  64         goto err;
  65     }
  66
  67     MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
  68     emLen = RSA_size(rsa);
  69     if (EM[0] & (0xFF << MSBits)) {
  70         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_FIRST_OCTET_INVALID);
  71         goto err;
  72     }
  73     if (MSBits == 0) {
  74         EM++;
  75         emLen--;
  76     }
  77     if (emLen < hLen + 2) {
  78         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);
  79         goto err;
  80     }
  81     if (sLen == RSA_PSS_SALTLEN_MAX) {
  82         sLen = emLen - hLen - 2;
  83     } else if (sLen > emLen - hLen - 2) { /* sLen can be small negative */
  84         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);
  85         goto err;
  86     }
  87     if (EM[emLen - 1] != 0xbc) {
  88         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_LAST_OCTET_INVALID);
  89         goto err;
  90     }
  91     maskedDBLen = emLen - hLen - 1;
  92     H = EM + maskedDBLen;
  93     DB = OPENSSL_malloc(maskedDBLen);
  94     if (DB == NULL) {
  95         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, ERR_R_MALLOC_FAILURE);
  96         goto err;
  97     }
  98     if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0)
  99         goto err;
 100     for (i = 0; i < maskedDBLen; i++)
 101         DB[i] ^= EM[i];
 102     if (MSBits)
 103         DB[0] &= 0xFF >> (8 - MSBits);
 104     for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) ;
 105     if (DB[i++] != 0x1) {
 106         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_RECOVERY_FAILED);
 107         goto err;
 108     }
 109     if (sLen != RSA_PSS_SALTLEN_AUTO && (maskedDBLen - i) != sLen) {
 110         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);
 111         goto err;
 112     }
 113     if (!EVP_DigestInit_ex(ctx, Hash, NULL)
 114         || !EVP_DigestUpdate(ctx, zeroes, sizeof(zeroes))
 115         || !EVP_DigestUpdate(ctx, mHash, hLen))
 116         goto err;
 117     if (maskedDBLen - i) {
 118         if (!EVP_DigestUpdate(ctx, DB + i, maskedDBLen - i))
 119             goto err;
 120     }
 121     if (!EVP_DigestFinal_ex(ctx, H_, NULL))
 122         goto err;
 123     if (memcmp(H_, H, hLen)) {
 124         RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_BAD_SIGNATURE);
 125         ret = 0;
 126     } else {
 127         ret = 1;
 128     }
 129
 130  err:
 131     OPENSSL_free(DB);
 132     EVP_MD_CTX_free(ctx);
 133
 134     return ret;
 135
 136 }
 137
 138 int RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,
 139                               const unsigned char *mHash,
 140                               const EVP_MD *Hash, int sLen)
 141 {
 142     return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen);
 143 }
 144
 145 int RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM,
 146                                    const unsigned char *mHash,
 147                                    const EVP_MD *Hash, const EVP_MD *mgf1Hash,
 148                                    int sLen)
 149 {
 150     int i;
 151     int ret = 0;
 152     int hLen, maskedDBLen, MSBits, emLen;
 153     unsigned char *H, *salt = NULL, *p;
 154     EVP_MD_CTX *ctx = NULL;
 155
 156     if (mgf1Hash == NULL)
 157         mgf1Hash = Hash;
 158
 159     hLen = EVP_MD_size(Hash);
 160     if (hLen < 0)
 161         goto err;
 162     /*-
 163      * Negative sLen has special meanings:
 164      *      -1      sLen == hLen
 165      *      -2      salt length is maximized
 166      *      -3      same as above (on signing)
 167      *      -N      reserved
 168      */
 169     if (sLen == RSA_PSS_SALTLEN_DIGEST) {
 170         sLen = hLen;
 171     } else if (sLen == RSA_PSS_SALTLEN_MAX_SIGN) {
 172         sLen = RSA_PSS_SALTLEN_MAX;
 173     } else if (sLen < RSA_PSS_SALTLEN_MAX) {
 174         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);
 175         goto err;
 176     }
 177
 178     MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
 179     emLen = RSA_size(rsa);
 180     if (MSBits == 0) {
 181         *EM++ = 0;
 182         emLen--;
 183     }
 184     if (emLen < hLen + 2) {
 185         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,
 186                RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
 187         goto err;
 188     }
 189     if (sLen == RSA_PSS_SALTLEN_MAX) {
 190         sLen = emLen - hLen - 2;
 191     } else if (sLen > emLen - hLen - 2) {
 192         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,
 193                RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
 194         goto err;
 195     }
 196     if (sLen > 0) {
 197         salt = OPENSSL_malloc(sLen);
 198         if (salt == NULL) {
 199             RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,
 200                    ERR_R_MALLOC_FAILURE);
 201             goto err;
 202         }
 203         if (RAND_bytes(salt, sLen) <= 0)
 204             goto err;
 205     }
 206     maskedDBLen = emLen - hLen - 1;
 207     H = EM + maskedDBLen;
 208     ctx = EVP_MD_CTX_new();
 209     if (ctx == NULL)
 210         goto err;
 211     if (!EVP_DigestInit_ex(ctx, Hash, NULL)
 212         || !EVP_DigestUpdate(ctx, zeroes, sizeof(zeroes))
 213         || !EVP_DigestUpdate(ctx, mHash, hLen))
 214         goto err;
 215     if (sLen && !EVP_DigestUpdate(ctx, salt, sLen))
 216         goto err;
 217     if (!EVP_DigestFinal_ex(ctx, H, NULL))
 218         goto err;
 219
 220     /* Generate dbMask in place then perform XOR on it */
 221     if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash))
 222         goto err;
 223
 224     p = EM;
 225
 226     /*
 227      * Initial PS XORs with all zeroes which is a NOP so just update pointer.
 228      * Note from a test above this value is guaranteed to be non-negative.
 229      */
 230     p += emLen - sLen - hLen - 2;
 231     *p++ ^= 0x1;
 232     if (sLen > 0) {
 233         for (i = 0; i < sLen; i++)
 234             *p++ ^= salt[i];
 235     }
 236     if (MSBits)
 237         EM[0] &= 0xFF >> (8 - MSBits);
 238
 239     /* H is already in place so just set final 0xbc */
 240
 241     EM[emLen - 1] = 0xbc;
 242
 243     ret = 1;
 244
 245  err:
 246     EVP_MD_CTX_free(ctx);
 247     OPENSSL_free(salt);
 248
 249     return ret;
 250
 251 }
 252
 253 #if defined(_MSC_VER)
 254 # pragma optimize("",on)
 255 #endif