/* Written by Dr Stephen N Henson (steve@openssl.org) 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 <openssl/rsa.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include <openssl/sha.h>
#include "internal.h"
#include "../internal.h"
/* TODO(fork): don't the check functions have to be constant time? */
int RSA_padding_add_PKCS1_type_1(uint8_t *to, size_t to_len,
const uint8_t *from, size_t from_len) {
/* See RFC 8017, section 9.2. */
if (to_len < RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
if (from_len > to_len - RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
to[0] = 0;
to[1] = 1;
OPENSSL_memset(to + 2, 0xff, to_len - 3 - from_len);
to[to_len - from_len - 1] = 0;
OPENSSL_memcpy(to + to_len - from_len, from, from_len);
return 1;
}
int RSA_padding_check_PKCS1_type_1(uint8_t *to, unsigned to_len,
const uint8_t *from, unsigned from_len) {
unsigned i, j;
const uint8_t *p;
if (from_len < 2) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL);
return -1;
}
p = from;
if ((*(p++) != 0) || (*(p++) != 1)) {
OPENSSL_PUT_ERROR(RSA, RSA_R_BLOCK_TYPE_IS_NOT_01);
return -1;
}
/* scan over padding data */
j = from_len - 2; /* one for leading 00, one for type. */
for (i = 0; i < j; i++) {
/* should decrypt to 0xff */
if (*p != 0xff) {
if (*p == 0) {
p++;
break;
} else {
OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_FIXED_HEADER_DECRYPT);
return -1;
}
}
p++;
}
if (i == j) {
OPENSSL_PUT_ERROR(RSA, RSA_R_NULL_BEFORE_BLOCK_MISSING);
return -1;
}
if (i < 8) {
OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_PAD_BYTE_COUNT);
return -1;
}
i++; /* Skip over the '\0' */
j -= i;
if (j > to_len) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);
return -1;
}
OPENSSL_memcpy(to, p, j);
return j;
}
static int rand_nonzero(uint8_t *out, size_t len) {
if (!RAND_bytes(out, len)) {
return 0;
}
for (size_t i = 0; i < len; i++) {
while (out[i] == 0) {
if (!RAND_bytes(out + i, 1)) {
return 0;
}
}
}
return 1;
}
int RSA_padding_add_PKCS1_type_2(uint8_t *to, size_t to_len,
const uint8_t *from, size_t from_len) {
/* See RFC 8017, section 7.2.1. */
if (to_len < RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
if (from_len > to_len - RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
to[0] = 0;
to[1] = 2;
size_t padding_len = to_len - 3 - from_len;
if (!rand_nonzero(to + 2, padding_len)) {
return 0;
}
to[2 + padding_len] = 0;
OPENSSL_memcpy(to + to_len - from_len, from, from_len);
return 1;
}
int RSA_padding_check_PKCS1_type_2(uint8_t *to, unsigned to_len,
const uint8_t *from, unsigned from_len) {
if (from_len == 0) {
OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY);
return -1;
}
/* PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography
* Standard", section 7.2.2. */
if (from_len < RSA_PKCS1_PADDING_SIZE) {
/* |from| is zero-padded to the size of the RSA modulus, a public value, so
* this can be rejected in non-constant time. */
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return -1;
}
unsigned first_byte_is_zero = constant_time_eq(from[0], 0);
unsigned second_byte_is_two = constant_time_eq(from[1], 2);
unsigned i, zero_index = 0, looking_for_index = ~0u;
for (i = 2; i < from_len; i++) {
unsigned equals0 = constant_time_is_zero(from[i]);
zero_index = constant_time_select(looking_for_index & equals0, (unsigned)i,
zero_index);
looking_for_index = constant_time_select(equals0, 0, looking_for_index);
}
/* The input must begin with 00 02. */
unsigned valid_index = first_byte_is_zero;
valid_index &= second_byte_is_two;
/* We must have found the end of PS. */
valid_index &= ~looking_for_index;
/* PS must be at least 8 bytes long, and it starts two bytes into |from|. */
valid_index &= constant_time_ge(zero_index, 2 + 8);
/* Skip the zero byte. */
zero_index++;
/* NOTE: Although this logic attempts to be constant time, the API contracts
* of this function and |RSA_decrypt| with |RSA_PKCS1_PADDING| make it
* impossible to completely avoid Bleichenbacher's attack. Consumers should
* use |RSA_unpad_key_pkcs1|. */
if (!valid_index) {
OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR);
return -1;
}
const unsigned msg_len = from_len - zero_index;
if (msg_len > to_len) {
/* This shouldn't happen because this function is always called with
* |to_len| as the key size and |from_len| is bounded by the key size. */
OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR);
return -1;
}
if (msg_len > INT_MAX) {
OPENSSL_PUT_ERROR(RSA, ERR_R_OVERFLOW);
return -1;
}
OPENSSL_memcpy(to, &from[zero_index], msg_len);
return (int)msg_len;
}
int RSA_padding_add_none(uint8_t *to, size_t to_len, const uint8_t *from,
size_t from_len) {
if (from_len > to_len) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
if (from_len < to_len) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL_FOR_KEY_SIZE);
return 0;
}
OPENSSL_memcpy(to, from, from_len);
return 1;
}
static int PKCS1_MGF1(uint8_t *out, size_t len, const uint8_t *seed,
size_t seed_len, const EVP_MD *md) {
int ret = 0;
EVP_MD_CTX ctx;
EVP_MD_CTX_init(&ctx);
size_t md_len = EVP_MD_size(md);
for (uint32_t i = 0; len > 0; i++) {
uint8_t counter[4];
counter[0] = (uint8_t)(i >> 24);
counter[1] = (uint8_t)(i >> 16);
counter[2] = (uint8_t)(i >> 8);
counter[3] = (uint8_t)i;
if (!EVP_DigestInit_ex(&ctx, md, NULL) ||
!EVP_DigestUpdate(&ctx, seed, seed_len) ||
!EVP_DigestUpdate(&ctx, counter, sizeof(counter))) {
goto err;
}
if (md_len <= len) {
if (!EVP_DigestFinal_ex(&ctx, out, NULL)) {
goto err;
}
out += md_len;
len -= md_len;
} else {
uint8_t digest[EVP_MAX_MD_SIZE];
if (!EVP_DigestFinal_ex(&ctx, digest, NULL)) {
goto err;
}
OPENSSL_memcpy(out, digest, len);
len = 0;
}
}
ret = 1;
err:
EVP_MD_CTX_cleanup(&ctx);
return ret;
}
int RSA_padding_add_PKCS1_OAEP_mgf1(uint8_t *to, size_t to_len,
const uint8_t *from, size_t from_len,
const uint8_t *param, size_t param_len,
const EVP_MD *md, const EVP_MD *mgf1md) {
if (md == NULL) {
md = EVP_sha1();
}
if (mgf1md == NULL) {
mgf1md = md;
}
size_t mdlen = EVP_MD_size(md);
if (to_len < 2 * mdlen + 2) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
size_t emlen = to_len - 1;
if (from_len > emlen - 2 * mdlen - 1) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
if (emlen < 2 * mdlen + 1) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
to[0] = 0;
uint8_t *seed = to + 1;
uint8_t *db = to + mdlen + 1;
if (!EVP_Digest(param, param_len, db, NULL, md, NULL)) {
return 0;
}
OPENSSL_memset(db + mdlen, 0, emlen - from_len - 2 * mdlen - 1);
db[emlen - from_len - mdlen - 1] = 0x01;
OPENSSL_memcpy(db + emlen - from_len - mdlen, from, from_len);
if (!RAND_bytes(seed, mdlen)) {
return 0;
}
uint8_t *dbmask = OPENSSL_malloc(emlen - mdlen);
if (dbmask == NULL) {
OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
return 0;
}
int ret = 0;
if (!PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md)) {
goto out;
}
for (size_t i = 0; i < emlen - mdlen; i++) {
db[i] ^= dbmask[i];
}
uint8_t seedmask[EVP_MAX_MD_SIZE];
if (!PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md)) {
goto out;
}
for (size_t i = 0; i < mdlen; i++) {
seed[i] ^= seedmask[i];
}
ret = 1;
out:
OPENSSL_free(dbmask);
return ret;
}
int RSA_padding_check_PKCS1_OAEP_mgf1(uint8_t *to, unsigned to_len,
const uint8_t *from, unsigned from_len,
const uint8_t *param, unsigned param_len,
const EVP_MD *md, const EVP_MD *mgf1md) {
unsigned i, dblen, mlen = -1, mdlen, bad, looking_for_one_byte, one_index = 0;
const uint8_t *maskeddb, *maskedseed;
uint8_t *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
if (md == NULL) {
md = EVP_sha1();
}
if (mgf1md == NULL) {
mgf1md = md;
}
mdlen = EVP_MD_size(md);
/* The encoded message is one byte smaller than the modulus to ensure that it
* doesn't end up greater than the modulus. Thus there's an extra "+1" here
* compared to https://tools.ietf.org/html/rfc2437#section-9.1.1.2. */
if (from_len < 1 + 2*mdlen + 1) {
/* 'from_len' is the length of the modulus, i.e. does not depend on the
* particular ciphertext. */
goto decoding_err;
}
dblen = from_len - mdlen - 1;
db = OPENSSL_malloc(dblen);
if (db == NULL) {
OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
goto err;
}
maskedseed = from + 1;
maskeddb = from + 1 + mdlen;
if (!PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md)) {
goto err;
}
for (i = 0; i < mdlen; i++) {
seed[i] ^= maskedseed[i];
}
if (!PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md)) {
goto err;
}
for (i = 0; i < dblen; i++) {
db[i] ^= maskeddb[i];
}
if (!EVP_Digest(param, param_len, phash, NULL, md, NULL)) {
goto err;
}
bad = ~constant_time_is_zero(CRYPTO_memcmp(db, phash, mdlen));
bad |= ~constant_time_is_zero(from[0]);
looking_for_one_byte = ~0u;
for (i = mdlen; i < dblen; i++) {
unsigned equals1 = constant_time_eq(db[i], 1);
unsigned equals0 = constant_time_eq(db[i], 0);
one_index = constant_time_select(looking_for_one_byte & equals1, i,
one_index);
looking_for_one_byte =
constant_time_select(equals1, 0, looking_for_one_byte);
bad |= looking_for_one_byte & ~equals0;
}
bad |= looking_for_one_byte;
if (bad) {
goto decoding_err;
}
one_index++;
mlen = dblen - one_index;
if (to_len < mlen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);
mlen = -1;
} else {
OPENSSL_memcpy(to, db + one_index, mlen);
}
OPENSSL_free(db);
return mlen;
decoding_err:
/* to avoid chosen ciphertext attacks, the error message should not reveal
* which kind of decoding error happened */
OPENSSL_PUT_ERROR(RSA, RSA_R_OAEP_DECODING_ERROR);
err:
OPENSSL_free(db);
return -1;
}
static const uint8_t kPSSZeroes[] = {0, 0, 0, 0, 0, 0, 0, 0};
int RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const uint8_t *mHash,
const EVP_MD *Hash, const EVP_MD *mgf1Hash,
const uint8_t *EM, int sLen) {
int i;
int ret = 0;
int maskedDBLen, MSBits, emLen;
size_t hLen;
const uint8_t *H;
uint8_t *DB = NULL;
EVP_MD_CTX ctx;
uint8_t H_[EVP_MAX_MD_SIZE];
EVP_MD_CTX_init(&ctx);
if (mgf1Hash == NULL) {
mgf1Hash = Hash;
}
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) {
OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);
goto err;
}
MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
emLen = RSA_size(rsa);
if (EM[0] & (0xFF << MSBits)) {
OPENSSL_PUT_ERROR(RSA, RSA_R_FIRST_OCTET_INVALID);
goto err;
}
if (MSBits == 0) {
EM++;
emLen--;
}
if (emLen < (int)hLen + 2 || emLen < ((int)hLen + sLen + 2)) {
/* sLen can be small negative */
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);
goto err;
}
if (EM[emLen - 1] != 0xbc) {
OPENSSL_PUT_ERROR(RSA, RSA_R_LAST_OCTET_INVALID);
goto err;
}
maskedDBLen = emLen - hLen - 1;
H = EM + maskedDBLen;
DB = OPENSSL_malloc(maskedDBLen);
if (!DB) {
OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash)) {
goto err;
}
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) {
OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_RECOVERY_FAILED);
goto err;
}
if (sLen >= 0 && (maskedDBLen - i) != sLen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);
goto err;
}
if (!EVP_DigestInit_ex(&ctx, Hash, NULL) ||
!EVP_DigestUpdate(&ctx, kPSSZeroes, sizeof(kPSSZeroes)) ||
!EVP_DigestUpdate(&ctx, mHash, hLen) ||
!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i) ||
!EVP_DigestFinal_ex(&ctx, H_, NULL)) {
goto err;
}
if (OPENSSL_memcmp(H_, H, hLen)) {
OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_SIGNATURE);
ret = 0;
} else {
ret = 1;
}
err:
OPENSSL_free(DB);
EVP_MD_CTX_cleanup(&ctx);
return ret;
}
int RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM,
const unsigned char *mHash,
const EVP_MD *Hash, const EVP_MD *mgf1Hash,
int sLenRequested) {
int ret = 0;
size_t maskedDBLen, MSBits, emLen;
size_t hLen;
unsigned char *H, *salt = NULL, *p;
if (mgf1Hash == NULL) {
mgf1Hash = Hash;
}
hLen = EVP_MD_size(Hash);
if (BN_is_zero(rsa->n)) {
OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY);
goto err;
}
MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
emLen = RSA_size(rsa);
if (MSBits == 0) {
assert(emLen >= 1);
*EM++ = 0;
emLen--;
}
if (emLen < hLen + 2) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
goto err;
}
/* Negative sLenRequested has special meanings:
* -1 sLen == hLen
* -2 salt length is maximized
* -N reserved */
size_t sLen;
if (sLenRequested == -1) {
sLen = hLen;
} else if (sLenRequested == -2) {
sLen = emLen - hLen - 2;
} else if (sLenRequested < 0) {
OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);
goto err;
} else {
sLen = (size_t)sLenRequested;
}
if (emLen - hLen - 2 < sLen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
goto err;
}
if (sLen > 0) {
salt = OPENSSL_malloc(sLen);
if (!salt) {
OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!RAND_bytes(salt, sLen)) {
goto err;
}
}
maskedDBLen = emLen - hLen - 1;
H = EM + maskedDBLen;
EVP_MD_CTX ctx;
EVP_MD_CTX_init(&ctx);
int digest_ok = EVP_DigestInit_ex(&ctx, Hash, NULL) &&
EVP_DigestUpdate(&ctx, kPSSZeroes, sizeof(kPSSZeroes)) &&
EVP_DigestUpdate(&ctx, mHash, hLen) &&
EVP_DigestUpdate(&ctx, salt, sLen) &&
EVP_DigestFinal_ex(&ctx, H, NULL);
EVP_MD_CTX_cleanup(&ctx);
if (!digest_ok) {
goto err;
}
/* Generate dbMask in place then perform XOR on it */
if (!PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) {
goto err;
}
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 (size_t 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:
OPENSSL_free(salt);
return ret;
}