/* 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 <string.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include <openssl/sha.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, unsigned tlen,
const uint8_t *from, unsigned flen) {
unsigned j;
uint8_t *p;
if (tlen < RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
if (flen > tlen - RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
p = (uint8_t *)to;
*(p++) = 0;
*(p++) = 1; /* Private Key BT (Block Type) */
/* pad out with 0xff data */
j = tlen - 3 - flen;
memset(p, 0xff, j);
p += j;
*(p++) = 0;
memcpy(p, from, (unsigned int)flen);
return 1;
}
int RSA_padding_check_PKCS1_type_1(uint8_t *to, unsigned tlen,
const uint8_t *from, unsigned flen) {
unsigned i, j;
const uint8_t *p;
if (flen < 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 = flen - 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 > tlen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);
return -1;
}
memcpy(to, p, j);
return j;
}
int RSA_padding_add_PKCS1_type_2(uint8_t *to, unsigned tlen,
const uint8_t *from, unsigned flen) {
unsigned i, j;
uint8_t *p;
if (tlen < RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
if (flen > tlen - RSA_PKCS1_PADDING_SIZE) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
p = (unsigned char *)to;
*(p++) = 0;
*(p++) = 2; /* Public Key BT (Block Type) */
/* pad out with non-zero random data */
j = tlen - 3 - flen;
if (!RAND_bytes(p, j)) {
return 0;
}
for (i = 0; i < j; i++) {
while (*p == 0) {
if (!RAND_bytes(p, 1)) {
return 0;
}
}
p++;
}
*(p++) = 0;
memcpy(p, from, (unsigned int)flen);
return 1;
}
/* constant_time_byte_eq returns 1 if |x| == |y| and 0 otherwise. */
static int constant_time_byte_eq(unsigned char a, unsigned char b) {
unsigned char z = ~(a ^ b);
z &= z >> 4;
z &= z >> 2;
z &= z >> 1;
return z;
}
/* constant_time_select returns |x| if |v| is 1 and |y| if |v| is 0.
* Its behavior is undefined if |v| takes any other value. */
static int constant_time_select(int v, int x, int y) {
return ((~(v - 1)) & x) | ((v - 1) & y);
}
/* constant_time_le returns 1 if |x| <= |y| and 0 otherwise.
* |x| and |y| must be positive. */
static int constant_time_le(int x, int y) {
return ((x - y - 1) >> (sizeof(int) * 8 - 1)) & 1;
}
int RSA_message_index_PKCS1_type_2(const uint8_t *from, size_t from_len,
size_t *out_index) {
size_t i;
int first_byte_is_zero, second_byte_is_two, looking_for_index;
int valid_index, zero_index = 0;
/* 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. */
*out_index = 0;
return 0;
}
first_byte_is_zero = constant_time_byte_eq(from[0], 0);
second_byte_is_two = constant_time_byte_eq(from[1], 2);
looking_for_index = 1;
for (i = 2; i < from_len; i++) {
int equals0 = constant_time_byte_eq(from[i], 0);
zero_index =
constant_time_select(looking_for_index & equals0, i, zero_index);
looking_for_index = constant_time_select(equals0, 0, looking_for_index);
}
/* The input must begin with 00 02. */
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_le(2 + 8, zero_index);
/* Skip the zero byte. */
zero_index++;
*out_index = constant_time_select(valid_index, zero_index, 0);
return valid_index;
}
int RSA_padding_check_PKCS1_type_2(uint8_t *to, unsigned tlen,
const uint8_t *from, unsigned flen) {
size_t msg_index, msg_len;
if (flen == 0) {
OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY);
return -1;
}
/* NOTE: Although |RSA_message_index_PKCS1_type_2| itself is constant time,
* the API contracts of this function and |RSA_decrypt| with
* |RSA_PKCS1_PADDING| make it impossible to completely avoid Bleichenbacher's
* attack. */
if (!RSA_message_index_PKCS1_type_2(from, flen, &msg_index)) {
OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR);
return -1;
}
msg_len = flen - msg_index;
if (msg_len > tlen) {
/* This shouldn't happen because this function is always called with |tlen|
* the key size and |flen| is bounded by the key size. */
OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR);
return -1;
}
memcpy(to, &from[msg_index], msg_len);
return msg_len;
}
int RSA_padding_add_none(uint8_t *to, unsigned tlen, const uint8_t *from, unsigned flen) {
if (flen > tlen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
return 0;
}
if (flen < tlen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL_FOR_KEY_SIZE);
return 0;
}
memcpy(to, from, (unsigned int)flen);
return 1;
}
int PKCS1_MGF1(uint8_t *mask, unsigned len, const uint8_t *seed,
unsigned seedlen, const EVP_MD *dgst) {
unsigned outlen = 0;
uint32_t i;
uint8_t cnt[4];
EVP_MD_CTX c;
uint8_t md[EVP_MAX_MD_SIZE];
unsigned mdlen;
int ret = -1;
EVP_MD_CTX_init(&c);
mdlen = EVP_MD_size(dgst);
for (i = 0; outlen < len; i++) {
cnt[0] = (uint8_t)((i >> 24) & 255);
cnt[1] = (uint8_t)((i >> 16) & 255);
cnt[2] = (uint8_t)((i >> 8)) & 255;
cnt[3] = (uint8_t)(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;
}
}
ret = 0;
err:
EVP_MD_CTX_cleanup(&c);
return ret;
}
int RSA_padding_add_PKCS1_OAEP_mgf1(uint8_t *to, unsigned tlen,
const uint8_t *from, unsigned flen,
const uint8_t *param, unsigned plen,
const EVP_MD *md, const EVP_MD *mgf1md) {
unsigned i, emlen, mdlen;
uint8_t *db, *seed;
uint8_t *dbmask = NULL, seedmask[EVP_MAX_MD_SIZE];
int ret = 0;
if (md == NULL) {
md = EVP_sha1();
}
if (mgf1md == NULL) {
mgf1md = md;
}
mdlen = EVP_MD_size(md);
if (tlen < 2 * mdlen + 2) {
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
emlen = tlen - 1;
if (flen > 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;
seed = to + 1;
db = to + mdlen + 1;
if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL)) {
return 0;
}
memset(db + mdlen, 0, emlen - flen - 2 * mdlen - 1);
db[emlen - flen - mdlen - 1] = 0x01;
memcpy(db + emlen - flen - mdlen, from, flen);
if (!RAND_bytes(seed, mdlen)) {
return 0;
}
dbmask = OPENSSL_malloc(emlen - mdlen);
if (dbmask == NULL) {
OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
return 0;
}
if (PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md) < 0) {
goto out;
}
for (i = 0; i < emlen - mdlen; i++) {
db[i] ^= dbmask[i];
}
if (PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md) < 0) {
goto out;
}
for (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 tlen,
const uint8_t *from, unsigned flen,
const uint8_t *param, unsigned plen,
const EVP_MD *md, const EVP_MD *mgf1md) {
unsigned i, dblen, mlen = -1, mdlen;
const uint8_t *maskeddb, *maskedseed;
uint8_t *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
int bad, looking_for_one_byte, one_index = 0;
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 (flen < 1 + 2*mdlen + 1) {
/* 'flen' is the length of the modulus, i.e. does not depend on the
* particular ciphertext. */
goto decoding_err;
}
dblen = flen - 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((void *)param, plen, phash, NULL, md, NULL)) {
goto err;
}
bad = CRYPTO_memcmp(db, phash, mdlen);
bad |= from[0];
looking_for_one_byte = 1;
for (i = mdlen; i < dblen; i++) {
int equals1 = constant_time_byte_eq(db[i], 1);
int equals0 = constant_time_byte_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 (tlen < mlen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);
mlen = -1;
} else {
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 unsigned char zeroes[] = {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 + 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) < 0) {
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, zeroes, sizeof zeroes) ||
!EVP_DigestUpdate(&ctx, mHash, hLen)) {
goto err;
}
if (maskedDBLen - i) {
if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i)) {
goto err;
}
}
if (!EVP_DigestFinal_ex(&ctx, H_, NULL)) {
goto err;
}
if (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 sLen) {
int i;
int ret = 0;
size_t maskedDBLen, MSBits, emLen;
size_t hLen;
unsigned char *H, *salt = NULL, *p;
EVP_MD_CTX ctx;
if (mgf1Hash == NULL) {
mgf1Hash = Hash;
}
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) {
OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);
goto err;
}
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 (sLen == -2) {
if (emLen < hLen + 2) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
goto err;
}
sLen = emLen - hLen - 2;
} else if (emLen < hLen + sLen + 2) {
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_init(&ctx);
if (!EVP_DigestInit_ex(&ctx, Hash, NULL) ||
!EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) ||
!EVP_DigestUpdate(&ctx, mHash, hLen)) {
goto err;
}
if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen)) {
goto err;
}
if (!EVP_DigestFinal_ex(&ctx, H, NULL)) {
goto err;
}
EVP_MD_CTX_cleanup(&ctx);
/* 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 (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;
}
