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/* rsa_pss.c */
/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
* project 2005.
*/
/* ====================================================================
* Copyright (c) 2005 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* licensing@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#include <stdio.h>
#include "cryptlib.h"
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/sha.h>
const static unsigned char zeroes[] = {0,0,0,0,0,0,0,0};
int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,
const EVP_MD *Hash, const unsigned char *EM, int sLen)
{
int i;
int ret = 0;
int hLen, maskedDBLen, MSBits, emLen;
const unsigned char *H;
unsigned char *DB = NULL;
EVP_MD_CTX ctx;
unsigned char H_[EVP_MAX_MD_SIZE];
hLen = EVP_MD_size(Hash);
/*
* Negative sLen has special meanings:
* -1 sLen == hLen
* -2 salt length is autorecovered from signature
* -N reserved
*/
if (sLen == -1) sLen = hLen;
else if (sLen == -2) sLen = -2;
else if (sLen < -2)
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
goto err;
}
MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
emLen = RSA_size(rsa);
if (EM[0] & (0xFF << MSBits))
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_FIRST_OCTET_INVALID);
goto err;
}
if (MSBits == 0)
{
EM++;
emLen--;
}
if (emLen < (hLen + sLen + 2)) /* sLen can be small negative */
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_DATA_TOO_LARGE);
goto err;
}
if (EM[emLen - 1] != 0xbc)
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_LAST_OCTET_INVALID);
goto err;
}
maskedDBLen = emLen - hLen - 1;
H = EM + maskedDBLen;
DB = OPENSSL_malloc(maskedDBLen);
if (!DB)
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, ERR_R_MALLOC_FAILURE);
goto err;
}
PKCS1_MGF1(DB, maskedDBLen, H, hLen, Hash);
for (i = 0; i < maskedDBLen; i++)
DB[i] ^= EM[i];
if (MSBits)
DB[0] &= 0xFF >> (8 - MSBits);
for (i = 0; DB[i] == 0 && i < (maskedDBLen-1); i++) ;
if (DB[i++] != 0x1)
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_RECOVERY_FAILED);
goto err;
}
if (sLen >= 0 && (maskedDBLen - i) != sLen)
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
goto err;
}
EVP_MD_CTX_init(&ctx);
EVP_DigestInit_ex(&ctx, Hash, NULL);
EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);
EVP_DigestUpdate(&ctx, mHash, hLen);
if (maskedDBLen - i)
EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i);
EVP_DigestFinal(&ctx, H_, NULL);
EVP_MD_CTX_cleanup(&ctx);
if (memcmp(H_, H, hLen))
{
RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_BAD_SIGNATURE);
ret = 0;
}
else
ret = 1;
err:
if (DB)
OPENSSL_free(DB);
return ret;
}
int RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,
const unsigned char *mHash,
const EVP_MD *Hash, int sLen)
{
int i;
int ret = 0;
int hLen, maskedDBLen, MSBits, emLen;
unsigned char *H, *salt = NULL, *p;
EVP_MD_CTX ctx;
hLen = EVP_MD_size(Hash);
/*
* Negative sLen has special meanings:
* -1 sLen == hLen
* -2 salt length is maximized
* -N reserved
*/
if (sLen == -1) sLen = hLen;
else if (sLen == -2) sLen = -2;
else if (sLen < -2)
{
RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
goto err;
}
MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
emLen = RSA_size(rsa);
if (MSBits == 0)
{
*EM++ = 0;
emLen--;
}
if (sLen == -2)
{
sLen = emLen - hLen - 2;
}
else if (emLen < (hLen + sLen + 2))
{
RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,
RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
goto err;
}
if (sLen > 0)
{
salt = OPENSSL_malloc(sLen);
if (!salt)
{
RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,
ERR_R_MALLOC_FAILURE);
goto err;
}
if (!RAND_bytes(salt, sLen))
goto err;
}
maskedDBLen = emLen - hLen - 1;
H = EM + maskedDBLen;
EVP_MD_CTX_init(&ctx);
EVP_DigestInit_ex(&ctx, Hash, NULL);
EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);
EVP_DigestUpdate(&ctx, mHash, hLen);
if (sLen)
EVP_DigestUpdate(&ctx, salt, sLen);
EVP_DigestFinal(&ctx, H, NULL);
EVP_MD_CTX_cleanup(&ctx);
/* Generate dbMask in place then perform XOR on it */
PKCS1_MGF1(EM, maskedDBLen, H, hLen, Hash);
p = EM;
/* Initial PS XORs with all zeroes which is a NOP so just update
* pointer. Note from a test above this value is guaranteed to
* be non-negative.
*/
p += emLen - sLen - hLen - 2;
*p++ ^= 0x1;
if (sLen > 0)
{
for (i = 0; i < sLen; i++)
*p++ ^= salt[i];
}
if (MSBits)
EM[0] &= 0xFF >> (8 - MSBits);
/* H is already in place so just set final 0xbc */
EM[emLen - 1] = 0xbc;
ret = 1;
err:
if (salt)
OPENSSL_free(salt);
return ret;
}
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