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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <stdint.h>
#include "error/s2n_errno.h"
#include "stuffer/s2n_stuffer.h"
#include "crypto/s2n_hash.h"
#include "crypto/s2n_openssl.h"
#include "crypto/s2n_rsa.h"
#include "crypto/s2n_rsa_pss.h"
#include "crypto/s2n_rsa_signing.h"
#include "crypto/s2n_pkey.h"
#include "utils/s2n_blob.h"
#include "utils/s2n_random.h"
#include "utils/s2n_safety.h"
#include "utils/s2n_blob.h"
/* Checks whether PSS Certs is supported */
int s2n_is_rsa_pss_certs_supported()
{
return RSA_PSS_CERTS_SUPPORTED;
}
#if RSA_PSS_CERTS_SUPPORTED
static int s2n_rsa_pss_size(const struct s2n_pkey *key)
{
notnull_check(key);
/* For more info, see: https://www.openssl.org/docs/man1.1.0/man3/EVP_PKEY_size.html */
return EVP_PKEY_size(key->pkey);
}
static int s2n_rsa_is_private_key(RSA *rsa_key)
{
const BIGNUM *d = NULL;
RSA_get0_key(rsa_key, NULL, NULL, &d);
if (d != NULL) {
return 1;
}
return 0;
}
int s2n_rsa_pss_key_sign(const struct s2n_pkey *priv, s2n_signature_algorithm sig_alg,
struct s2n_hash_state *digest, struct s2n_blob *signature_out)
{
notnull_check(priv);
sig_alg_check(sig_alg, S2N_SIGNATURE_RSA_PSS_PSS);
/* Not Possible to Sign with Public Key */
S2N_ERROR_IF(!s2n_rsa_is_private_key(priv->key.rsa_key.rsa), S2N_ERR_KEY_MISMATCH);
return s2n_rsa_pss_sign(priv, digest, signature_out);
}
int s2n_rsa_pss_key_verify(const struct s2n_pkey *pub, s2n_signature_algorithm sig_alg,
struct s2n_hash_state *digest, struct s2n_blob *signature_in)
{
notnull_check(pub);
sig_alg_check(sig_alg, S2N_SIGNATURE_RSA_PSS_PSS);
/* Using Private Key to Verify means the public/private keys were likely swapped, and likely indicates a bug. */
S2N_ERROR_IF(s2n_rsa_is_private_key(pub->key.rsa_key.rsa), S2N_ERR_KEY_MISMATCH);
return s2n_rsa_pss_verify(pub, digest, signature_in);
}
static int s2n_rsa_pss_validate_sign_verify_match(const struct s2n_pkey *pub, const struct s2n_pkey *priv)
{
/* Generate a random blob to sign and verify */
s2n_stack_blob(random_data, RSA_PSS_SIGN_VERIFY_RANDOM_BLOB_SIZE, RSA_PSS_SIGN_VERIFY_RANDOM_BLOB_SIZE);
GUARD_AS_POSIX(s2n_get_private_random_data(&random_data));
/* Sign/Verify API's only accept Hashes, so hash our Random Data */
DEFER_CLEANUP(struct s2n_hash_state sign_hash = {0}, s2n_hash_free);
DEFER_CLEANUP(struct s2n_hash_state verify_hash = {0}, s2n_hash_free);
GUARD(s2n_hash_new(&sign_hash));
GUARD(s2n_hash_new(&verify_hash));
GUARD(s2n_hash_init(&sign_hash, S2N_HASH_SHA256));
GUARD(s2n_hash_init(&verify_hash, S2N_HASH_SHA256));
GUARD(s2n_hash_update(&sign_hash, random_data.data, random_data.size));
GUARD(s2n_hash_update(&verify_hash, random_data.data, random_data.size));
/* Sign and Verify the Hash of the Random Blob */
s2n_stack_blob(signature_data, RSA_PSS_SIGN_VERIFY_SIGNATURE_SIZE, RSA_PSS_SIGN_VERIFY_SIGNATURE_SIZE);
GUARD(s2n_rsa_pss_key_sign(priv, S2N_SIGNATURE_RSA_PSS_PSS, &sign_hash, &signature_data));
GUARD(s2n_rsa_pss_key_verify(pub, S2N_SIGNATURE_RSA_PSS_PSS, &verify_hash, &signature_data));
return 0;
}
static int s2n_rsa_validate_params_equal(const RSA *pub, const RSA *priv)
{
const BIGNUM *pub_val_e = NULL;
const BIGNUM *pub_val_n = NULL;
RSA_get0_key(pub, &pub_val_n, &pub_val_e, NULL);
const BIGNUM *priv_val_e = NULL;
const BIGNUM *priv_val_n = NULL;
RSA_get0_key(priv, &priv_val_n, &priv_val_e, NULL);
if (pub_val_e == NULL || priv_val_e == NULL) {
S2N_ERROR(S2N_ERR_KEY_CHECK);
}
if (pub_val_n == NULL || priv_val_n == NULL) {
S2N_ERROR(S2N_ERR_KEY_CHECK);
}
S2N_ERROR_IF(BN_cmp(pub_val_e, priv_val_e) != 0, S2N_ERR_KEY_MISMATCH);
S2N_ERROR_IF(BN_cmp(pub_val_n, priv_val_n) != 0, S2N_ERR_KEY_MISMATCH);
return 0;
}
static int s2n_rsa_validate_params_match(const struct s2n_pkey *pub, const struct s2n_pkey *priv)
{
notnull_check(pub);
notnull_check(priv);
/* OpenSSL Documentation Links:
* - https://www.openssl.org/docs/manmaster/man3/EVP_PKEY_get0_RSA.html
* - https://www.openssl.org/docs/manmaster/man3/RSA_get0_key.html
*/
RSA *pub_rsa_key = pub->key.rsa_key.rsa;
RSA *priv_rsa_key = priv->key.rsa_key.rsa;
notnull_check(pub_rsa_key);
notnull_check(priv_rsa_key);
GUARD(s2n_rsa_validate_params_equal(pub_rsa_key, priv_rsa_key));
return 0;
}
static int s2n_rsa_pss_keys_match(const struct s2n_pkey *pub, const struct s2n_pkey *priv)
{
notnull_check(pub);
notnull_check(pub->pkey);
notnull_check(priv);
notnull_check(priv->pkey);
GUARD(s2n_rsa_validate_params_match(pub, priv));
/* Validate that verify(sign(message)) for a random message is verified correctly */
GUARD(s2n_rsa_pss_validate_sign_verify_match(pub, priv));
return 0;
}
static int s2n_rsa_pss_key_free(struct s2n_pkey *pkey)
{
/* This object does not own the reference to the key --
* s2n_pkey handles it. */
return 0;
}
int s2n_evp_pkey_to_rsa_pss_public_key(struct s2n_rsa_key *rsa_key, EVP_PKEY *pkey) {
RSA *pub_rsa_key = EVP_PKEY_get0_RSA(pkey);
S2N_ERROR_IF(s2n_rsa_is_private_key(pub_rsa_key), S2N_ERR_KEY_MISMATCH);
rsa_key->rsa = pub_rsa_key;
return 0;
}
int s2n_evp_pkey_to_rsa_pss_private_key(struct s2n_rsa_key *rsa_key, EVP_PKEY *pkey)
{
RSA *priv_rsa_key = EVP_PKEY_get0_RSA(pkey);
notnull_check(priv_rsa_key);
/* Documentation: https://www.openssl.org/docs/man1.1.1/man3/RSA_check_key.html */
S2N_ERROR_IF(!s2n_rsa_is_private_key(priv_rsa_key), S2N_ERR_KEY_MISMATCH);
/* Check that the mandatory properties of a RSA Private Key are valid.
* - Documentation: https://www.openssl.org/docs/man1.1.1/man3/RSA_check_key.html
*/
GUARD_OSSL(RSA_check_key(priv_rsa_key), S2N_ERR_KEY_CHECK);
rsa_key->rsa = priv_rsa_key;
return 0;
}
int s2n_rsa_pss_pkey_init(struct s2n_pkey *pkey)
{
GUARD(s2n_rsa_pkey_init(pkey));
pkey->size = &s2n_rsa_pss_size;
pkey->sign = &s2n_rsa_pss_key_sign;
pkey->verify = &s2n_rsa_pss_key_verify;
/* RSA PSS only supports Sign and Verify.
* RSA PSS should never be used for Key Exchange. ECDHE should be used instead since it provides Forward Secrecy. */
pkey->encrypt = NULL; /* No function for encryption */
pkey->decrypt = NULL; /* No function for decryption */
pkey->match = &s2n_rsa_pss_keys_match;
pkey->free = &s2n_rsa_pss_key_free;
return 0;
}
#else
int s2n_evp_pkey_to_rsa_pss_public_key(struct s2n_rsa_key *rsa_pss_key, EVP_PKEY *pkey)
{
S2N_ERROR(S2N_RSA_PSS_NOT_SUPPORTED);
}
int s2n_evp_pkey_to_rsa_pss_private_key(struct s2n_rsa_key *rsa_pss_key, EVP_PKEY *pkey)
{
S2N_ERROR(S2N_RSA_PSS_NOT_SUPPORTED);
}
int s2n_rsa_pss_pkey_init(struct s2n_pkey *pkey)
{
S2N_ERROR(S2N_RSA_PSS_NOT_SUPPORTED);
}
#endif
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