ref: 94f2907dc40a6415a10c252cb9ba3971f1f7e838
dir: /third_party/boringssl/src/crypto/rsa_extra/rsa_crypt.c/
/* Copyright (C) 1995-1998 Eric Young ([email protected])
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young ([email protected]).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson ([email protected]).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* 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 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 acknowledgement:
* "This product includes cryptographic software written by
* Eric Young ([email protected])"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson ([email protected])"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS 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 AUTHOR OR 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.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/base.h>
#include <limits.h>
#include <openssl/err.h>
#include <openssl/rsa.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/mem.h>
#include <openssl/evp.h>
#include "../fipsmodule/bn/internal.h"
#include "../fipsmodule/rsa/internal.h"
#include "../internal.h"
#include "internal.h"
static void rand_nonzero(uint8_t *out, size_t len) {
RAND_bytes(out, len);
for (size_t i = 0; i < len; i++) {
// Zero values are replaced, and the distribution of zero and non-zero bytes
// is public, so leaking this is safe.
while (constant_time_declassify_int(out[i] == 0)) {
RAND_bytes(out + i, 1);
}
}
}
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;
uint8_t *dbmask = NULL;
int ret = 0;
if (!EVP_Digest(param, param_len, db, NULL, md, NULL)) {
goto out;
}
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)) {
goto out;
}
dbmask = OPENSSL_malloc(emlen - mdlen);
if (dbmask == NULL) {
goto out;
}
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 *out, size_t *out_len,
size_t max_out, const uint8_t *from,
size_t from_len, const uint8_t *param,
size_t param_len, const EVP_MD *md,
const EVP_MD *mgf1md) {
uint8_t *db = NULL;
if (md == NULL) {
md = EVP_sha1();
}
if (mgf1md == NULL) {
mgf1md = md;
}
size_t 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;
}
size_t dblen = from_len - mdlen - 1;
db = OPENSSL_malloc(dblen);
if (db == NULL) {
goto err;
}
const uint8_t *maskedseed = from + 1;
const uint8_t *maskeddb = from + 1 + mdlen;
uint8_t seed[EVP_MAX_MD_SIZE];
if (!PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md)) {
goto err;
}
for (size_t i = 0; i < mdlen; i++) {
seed[i] ^= maskedseed[i];
}
if (!PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md)) {
goto err;
}
for (size_t i = 0; i < dblen; i++) {
db[i] ^= maskeddb[i];
}
uint8_t phash[EVP_MAX_MD_SIZE];
if (!EVP_Digest(param, param_len, phash, NULL, md, NULL)) {
goto err;
}
crypto_word_t bad = ~constant_time_is_zero_w(CRYPTO_memcmp(db, phash, mdlen));
bad |= ~constant_time_is_zero_w(from[0]);
crypto_word_t looking_for_one_byte = CONSTTIME_TRUE_W;
size_t one_index = 0;
for (size_t i = mdlen; i < dblen; i++) {
crypto_word_t equals1 = constant_time_eq_w(db[i], 1);
crypto_word_t equals0 = constant_time_eq_w(db[i], 0);
one_index =
constant_time_select_w(looking_for_one_byte & equals1, i, one_index);
looking_for_one_byte =
constant_time_select_w(equals1, 0, looking_for_one_byte);
bad |= looking_for_one_byte & ~equals0;
}
bad |= looking_for_one_byte;
// Whether the overall padding was valid or not in OAEP is public.
if (constant_time_declassify_w(bad)) {
goto decoding_err;
}
// Once the padding is known to be valid, the output length is also public.
static_assert(sizeof(size_t) <= sizeof(crypto_word_t),
"size_t does not fit in crypto_word_t");
one_index = constant_time_declassify_w(one_index);
one_index++;
size_t mlen = dblen - one_index;
if (max_out < mlen) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);
goto err;
}
OPENSSL_memcpy(out, db + one_index, mlen);
*out_len = mlen;
OPENSSL_free(db);
return 1;
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 0;
}
static 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;
rand_nonzero(to + 2, padding_len);
to[2 + padding_len] = 0;
OPENSSL_memcpy(to + to_len - from_len, from, from_len);
return 1;
}
static int rsa_padding_check_PKCS1_type_2(uint8_t *out, size_t *out_len,
size_t max_out, const uint8_t *from,
size_t from_len) {
if (from_len == 0) {
OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY);
return 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.
OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);
return 0;
}
crypto_word_t first_byte_is_zero = constant_time_eq_w(from[0], 0);
crypto_word_t second_byte_is_two = constant_time_eq_w(from[1], 2);
crypto_word_t zero_index = 0, looking_for_index = CONSTTIME_TRUE_W;
for (size_t i = 2; i < from_len; i++) {
crypto_word_t equals0 = constant_time_is_zero_w(from[i]);
zero_index =
constant_time_select_w(looking_for_index & equals0, i, zero_index);
looking_for_index = constant_time_select_w(equals0, 0, looking_for_index);
}
// The input must begin with 00 02.
crypto_word_t 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_w(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_PADDING_NONE| and perform the padding check in constant-time
// combined with a swap to a random session key or other mitigation.
CONSTTIME_DECLASSIFY(&valid_index, sizeof(valid_index));
CONSTTIME_DECLASSIFY(&zero_index, sizeof(zero_index));
if (!valid_index) {
OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR);
return 0;
}
const size_t msg_len = from_len - zero_index;
if (msg_len > max_out) {
// This shouldn't happen because this function is always called with
// |max_out| as the key size and |from_len| is bounded by the key size.
OPENSSL_PUT_ERROR(RSA, RSA_R_PKCS_DECODING_ERROR);
return 0;
}
OPENSSL_memcpy(out, &from[zero_index], msg_len);
*out_len = msg_len;
return 1;
}
int RSA_public_encrypt(size_t flen, const uint8_t *from, uint8_t *to, RSA *rsa,
int padding) {
size_t out_len;
if (!RSA_encrypt(rsa, &out_len, to, RSA_size(rsa), from, flen, padding)) {
return -1;
}
if (out_len > INT_MAX) {
OPENSSL_PUT_ERROR(RSA, ERR_R_OVERFLOW);
return -1;
}
return (int)out_len;
}
int RSA_private_encrypt(size_t flen, const uint8_t *from, uint8_t *to, RSA *rsa,
int padding) {
size_t out_len;
if (!RSA_sign_raw(rsa, &out_len, to, RSA_size(rsa), from, flen, padding)) {
return -1;
}
if (out_len > INT_MAX) {
OPENSSL_PUT_ERROR(RSA, ERR_R_OVERFLOW);
return -1;
}
return (int)out_len;
}
int RSA_encrypt(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out,
const uint8_t *in, size_t in_len, int padding) {
if (rsa->n == NULL || rsa->e == NULL) {
OPENSSL_PUT_ERROR(RSA, RSA_R_VALUE_MISSING);
return 0;
}
if (!rsa_check_public_key(rsa)) {
return 0;
}
const unsigned rsa_size = RSA_size(rsa);
BIGNUM *f, *result;
uint8_t *buf = NULL;
BN_CTX *ctx = NULL;
int i, ret = 0;
if (max_out < rsa_size) {
OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL);
return 0;
}
ctx = BN_CTX_new();
if (ctx == NULL) {
goto err;
}
BN_CTX_start(ctx);
f = BN_CTX_get(ctx);
result = BN_CTX_get(ctx);
buf = OPENSSL_malloc(rsa_size);
if (!f || !result || !buf) {
goto err;
}
switch (padding) {
case RSA_PKCS1_PADDING:
i = rsa_padding_add_PKCS1_type_2(buf, rsa_size, in, in_len);
break;
case RSA_PKCS1_OAEP_PADDING:
// Use the default parameters: SHA-1 for both hashes and no label.
i = RSA_padding_add_PKCS1_OAEP_mgf1(buf, rsa_size, in, in_len, NULL, 0,
NULL, NULL);
break;
case RSA_NO_PADDING:
i = RSA_padding_add_none(buf, rsa_size, in, in_len);
break;
default:
OPENSSL_PUT_ERROR(RSA, RSA_R_UNKNOWN_PADDING_TYPE);
goto err;
}
if (i <= 0) {
goto err;
}
if (BN_bin2bn(buf, rsa_size, f) == NULL) {
goto err;
}
if (BN_ucmp(f, rsa->n) >= 0) {
// usually the padding functions would catch this
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
goto err;
}
if (!BN_MONT_CTX_set_locked(&rsa->mont_n, &rsa->lock, rsa->n, ctx) ||
!BN_mod_exp_mont(result, f, rsa->e, &rsa->mont_n->N, ctx, rsa->mont_n)) {
goto err;
}
// put in leading 0 bytes if the number is less than the length of the
// modulus
if (!BN_bn2bin_padded(out, rsa_size, result)) {
OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
goto err;
}
*out_len = rsa_size;
ret = 1;
err:
if (ctx != NULL) {
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}
OPENSSL_free(buf);
return ret;
}
static int rsa_default_decrypt(RSA *rsa, size_t *out_len, uint8_t *out,
size_t max_out, const uint8_t *in, size_t in_len,
int padding) {
const unsigned rsa_size = RSA_size(rsa);
uint8_t *buf = NULL;
int ret = 0;
if (max_out < rsa_size) {
OPENSSL_PUT_ERROR(RSA, RSA_R_OUTPUT_BUFFER_TOO_SMALL);
return 0;
}
if (padding == RSA_NO_PADDING) {
buf = out;
} else {
// Allocate a temporary buffer to hold the padded plaintext.
buf = OPENSSL_malloc(rsa_size);
if (buf == NULL) {
goto err;
}
}
if (in_len != rsa_size) {
OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_LEN_NOT_EQUAL_TO_MOD_LEN);
goto err;
}
if (!rsa_private_transform(rsa, buf, in, rsa_size)) {
goto err;
}
switch (padding) {
case RSA_PKCS1_PADDING:
ret =
rsa_padding_check_PKCS1_type_2(out, out_len, rsa_size, buf, rsa_size);
break;
case RSA_PKCS1_OAEP_PADDING:
// Use the default parameters: SHA-1 for both hashes and no label.
ret = RSA_padding_check_PKCS1_OAEP_mgf1(out, out_len, rsa_size, buf,
rsa_size, NULL, 0, NULL, NULL);
break;
case RSA_NO_PADDING:
*out_len = rsa_size;
ret = 1;
break;
default:
OPENSSL_PUT_ERROR(RSA, RSA_R_UNKNOWN_PADDING_TYPE);
goto err;
}
CONSTTIME_DECLASSIFY(&ret, sizeof(ret));
if (!ret) {
OPENSSL_PUT_ERROR(RSA, RSA_R_PADDING_CHECK_FAILED);
} else {
CONSTTIME_DECLASSIFY(out, *out_len);
}
err:
if (padding != RSA_NO_PADDING) {
OPENSSL_free(buf);
}
return ret;
}
int RSA_decrypt(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out,
const uint8_t *in, size_t in_len, int padding) {
if (rsa->meth->decrypt) {
return rsa->meth->decrypt(rsa, out_len, out, max_out, in, in_len, padding);
}
return rsa_default_decrypt(rsa, out_len, out, max_out, in, in_len, padding);
}
int RSA_private_decrypt(size_t flen, const uint8_t *from, uint8_t *to, RSA *rsa,
int padding) {
size_t out_len;
if (!RSA_decrypt(rsa, &out_len, to, RSA_size(rsa), from, flen, padding)) {
return -1;
}
if (out_len > INT_MAX) {
OPENSSL_PUT_ERROR(RSA, ERR_R_OVERFLOW);
return -1;
}
return (int)out_len;
}
int RSA_public_decrypt(size_t flen, const uint8_t *from, uint8_t *to, RSA *rsa,
int padding) {
size_t out_len;
if (!RSA_verify_raw(rsa, &out_len, to, RSA_size(rsa), from, flen, padding)) {
return -1;
}
if (out_len > INT_MAX) {
OPENSSL_PUT_ERROR(RSA, ERR_R_OVERFLOW);
return -1;
}
return (int)out_len;
}