pineapple/externals/libressl/crypto/rsa/rsa_oaep.c
2022-04-24 22:29:35 +02:00

358 lines
11 KiB
C
Executable file

/* $OpenBSD: rsa_oaep.c,v 1.35 2022/02/20 19:16:34 tb Exp $ */
/*
* Copyright 1999-2018 The OpenSSL Project Authors. 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
* openssl-core@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).
*
*/
/* EME-OAEP as defined in RFC 2437 (PKCS #1 v2.0) */
/* See Victor Shoup, "OAEP reconsidered," Nov. 2000,
* <URL: http://www.shoup.net/papers/oaep.ps.Z>
* for problems with the security proof for the
* original OAEP scheme, which EME-OAEP is based on.
*
* A new proof can be found in E. Fujisaki, T. Okamoto,
* D. Pointcheval, J. Stern, "RSA-OEAP is Still Alive!",
* Dec. 2000, <URL: http://eprint.iacr.org/2000/061/>.
* The new proof has stronger requirements for the
* underlying permutation: "partial-one-wayness" instead
* of one-wayness. For the RSA function, this is
* an equivalent notion.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/sha.h>
#include "constant_time_locl.h"
#include "evp_locl.h"
#include "rsa_locl.h"
int
RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
const unsigned char *from, int flen, const unsigned char *param, int plen)
{
return RSA_padding_add_PKCS1_OAEP_mgf1(to, tlen, from, flen, param,
plen, NULL, NULL);
}
int
RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
const unsigned char *from, int flen, const unsigned char *param, int plen,
const EVP_MD *md, const EVP_MD *mgf1md)
{
int i, emlen = tlen - 1;
unsigned char *db, *seed;
unsigned char *dbmask = NULL;
unsigned char seedmask[EVP_MAX_MD_SIZE];
int mdlen, dbmask_len = 0;
int rv = 0;
if (md == NULL)
md = EVP_sha1();
if (mgf1md == NULL)
mgf1md = md;
if ((mdlen = EVP_MD_size(md)) <= 0)
goto err;
if (flen > emlen - 2 * mdlen - 1) {
RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
goto err;
}
if (emlen < 2 * mdlen + 1) {
RSAerror(RSA_R_KEY_SIZE_TOO_SMALL);
goto err;
}
to[0] = 0;
seed = to + 1;
db = to + mdlen + 1;
if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL))
goto err;
memset(db + mdlen, 0, emlen - flen - 2 * mdlen - 1);
db[emlen - flen - mdlen - 1] = 0x01;
memcpy(db + emlen - flen - mdlen, from, flen);
arc4random_buf(seed, mdlen);
dbmask_len = emlen - mdlen;
if ((dbmask = malloc(dbmask_len)) == NULL) {
RSAerror(ERR_R_MALLOC_FAILURE);
goto err;
}
if (PKCS1_MGF1(dbmask, dbmask_len, seed, mdlen, mgf1md) < 0)
goto err;
for (i = 0; i < dbmask_len; i++)
db[i] ^= dbmask[i];
if (PKCS1_MGF1(seedmask, mdlen, db, dbmask_len, mgf1md) < 0)
goto err;
for (i = 0; i < mdlen; i++)
seed[i] ^= seedmask[i];
rv = 1;
err:
explicit_bzero(seedmask, sizeof(seedmask));
freezero(dbmask, dbmask_len);
return rv;
}
int
RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
const unsigned char *from, int flen, int num, const unsigned char *param,
int plen)
{
return RSA_padding_check_PKCS1_OAEP_mgf1(to, tlen, from, flen, num,
param, plen, NULL, NULL);
}
int
RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
const unsigned char *from, int flen, int num, const unsigned char *param,
int plen, const EVP_MD *md, const EVP_MD *mgf1md)
{
int i, dblen = 0, mlen = -1, one_index = 0, msg_index;
unsigned int good = 0, found_one_byte, mask;
const unsigned char *maskedseed, *maskeddb;
unsigned char seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
unsigned char *db = NULL, *em = NULL;
int mdlen;
if (md == NULL)
md = EVP_sha1();
if (mgf1md == NULL)
mgf1md = md;
if ((mdlen = EVP_MD_size(md)) <= 0)
return -1;
if (tlen <= 0 || flen <= 0)
return -1;
/*
* |num| is the length of the modulus; |flen| is the length of the
* encoded message. Therefore, for any |from| that was obtained by
* decrypting a ciphertext, we must have |flen| <= |num|. Similarly,
* |num| >= 2 * |mdlen| + 2 must hold for the modulus irrespective
* of the ciphertext, see PKCS #1 v2.2, section 7.1.2.
* This does not leak any side-channel information.
*/
if (num < flen || num < 2 * mdlen + 2) {
RSAerror(RSA_R_OAEP_DECODING_ERROR);
return -1;
}
dblen = num - mdlen - 1;
if ((db = malloc(dblen)) == NULL) {
RSAerror(ERR_R_MALLOC_FAILURE);
goto cleanup;
}
if ((em = malloc(num)) == NULL) {
RSAerror(ERR_R_MALLOC_FAILURE);
goto cleanup;
}
/*
* Caller is encouraged to pass zero-padded message created with
* BN_bn2binpad. Trouble is that since we can't read out of |from|'s
* bounds, it's impossible to have an invariant memory access pattern
* in case |from| was not zero-padded in advance.
*/
for (from += flen, em += num, i = 0; i < num; i++) {
mask = ~constant_time_is_zero(flen);
flen -= 1 & mask;
from -= 1 & mask;
*--em = *from & mask;
}
/*
* The first byte must be zero, however we must not leak if this is
* true. See James H. Manger, "A Chosen Ciphertext Attack on RSA
* Optimal Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001).
*/
good = constant_time_is_zero(em[0]);
maskedseed = em + 1;
maskeddb = em + 1 + mdlen;
if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))
goto cleanup;
for (i = 0; i < mdlen; i++)
seed[i] ^= maskedseed[i];
if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md))
goto cleanup;
for (i = 0; i < dblen; i++)
db[i] ^= maskeddb[i];
if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL))
goto cleanup;
good &= constant_time_is_zero(timingsafe_memcmp(db, phash, mdlen));
found_one_byte = 0;
for (i = mdlen; i < dblen; i++) {
/*
* Padding consists of a number of 0-bytes, followed by a 1.
*/
unsigned int equals1 = constant_time_eq(db[i], 1);
unsigned int equals0 = constant_time_is_zero(db[i]);
one_index = constant_time_select_int(~found_one_byte & equals1,
i, one_index);
found_one_byte |= equals1;
good &= (found_one_byte | equals0);
}
good &= found_one_byte;
/*
* At this point |good| is zero unless the plaintext was valid,
* so plaintext-awareness ensures timing side-channels are no longer a
* concern.
*/
msg_index = one_index + 1;
mlen = dblen - msg_index;
/*
* For good measure, do this check in constant time as well.
*/
good &= constant_time_ge(tlen, mlen);
/*
* Even though we can't fake result's length, we can pretend copying
* |tlen| bytes where |mlen| bytes would be real. The last |tlen| of
* |dblen| bytes are viewed as a circular buffer starting at |tlen|-|mlen'|,
* where |mlen'| is the "saturated" |mlen| value. Deducing information
* about failure or |mlen| would require an attacker to observe
* memory access patterns with byte granularity *as it occurs*. It
* should be noted that failure is indistinguishable from normal
* operation if |tlen| is fixed by protocol.
*/
tlen = constant_time_select_int(constant_time_lt(dblen - mdlen - 1, tlen),
dblen - mdlen - 1, tlen);
msg_index = constant_time_select_int(good, msg_index, dblen - tlen);
mlen = dblen - msg_index;
for (mask = good, i = 0; i < tlen; i++) {
unsigned int equals = constant_time_eq(msg_index, dblen);
msg_index -= tlen & equals; /* rewind at EOF */
mask &= ~equals; /* mask = 0 at EOF */
to[i] = constant_time_select_8(mask, db[msg_index++], to[i]);
}
/*
* To avoid chosen ciphertext attacks, the error message should not
* reveal which kind of decoding error happened.
*/
RSAerror(RSA_R_OAEP_DECODING_ERROR);
err_clear_last_constant_time(1 & good);
cleanup:
explicit_bzero(seed, sizeof(seed));
freezero(db, dblen);
freezero(em, num);
return constant_time_select_int(good, mlen, -1);
}
int
PKCS1_MGF1(unsigned char *mask, long len, const unsigned char *seed,
long seedlen, const EVP_MD *dgst)
{
long i, outlen = 0;
unsigned char cnt[4];
EVP_MD_CTX c;
unsigned char md[EVP_MAX_MD_SIZE];
int mdlen;
int rv = -1;
EVP_MD_CTX_init(&c);
mdlen = EVP_MD_size(dgst);
if (mdlen < 0)
goto err;
for (i = 0; outlen < len; i++) {
cnt[0] = (unsigned char)((i >> 24) & 255);
cnt[1] = (unsigned char)((i >> 16) & 255);
cnt[2] = (unsigned char)((i >> 8)) & 255;
cnt[3] = (unsigned char)(i & 255);
if (!EVP_DigestInit_ex(&c, dgst, NULL) ||
!EVP_DigestUpdate(&c, seed, seedlen) ||
!EVP_DigestUpdate(&c, cnt, 4))
goto err;
if (outlen + mdlen <= len) {
if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))
goto err;
outlen += mdlen;
} else {
if (!EVP_DigestFinal_ex(&c, md, NULL))
goto err;
memcpy(mask + outlen, md, len - outlen);
outlen = len;
}
}
rv = 0;
err:
EVP_MD_CTX_cleanup(&c);
return rv;
}