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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 "crypto/s2n_fips.h"
#include "tls/s2n_cipher_suites.h"
#include "tls/s2n_tls_parameters.h"
#include "utils/s2n_result.h"
/* FIPS requires at least 112 bits of security.
* https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-107r1.pdf */
const s2n_hash_algorithm fips_hash_algs[] = {
S2N_HASH_SHA224,
S2N_HASH_SHA256,
S2N_HASH_SHA384,
S2N_HASH_SHA512,
};
S2N_RESULT s2n_fips_validate_hash_algorithm(s2n_hash_algorithm hash_alg, bool *valid)
{
RESULT_ENSURE_REF(valid);
*valid = false;
for (size_t i = 0; i < s2n_array_len(fips_hash_algs); i++) {
if (fips_hash_algs[i] == hash_alg) {
*valid = true;
return S2N_RESULT_OK;
}
}
return S2N_RESULT_OK;
}
/* https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-52r2.pdf */
const uint8_t fips_cipher_suite_ianas[][2] = {
/* 3.3.1.1.1 Cipher Suites for ECDSA Certificates */
{ TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 },
{ TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 },
{ TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 },
{ TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 },
{ TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA },
{ TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA },
/* 3.3.1.1.2 Cipher Suites for RSA Certificates */
{ TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 },
{ TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 },
{ TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 },
{ TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 },
{ TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 },
{ TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 },
{ TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 },
{ TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 },
{ TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA },
{ TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA },
{ TLS_DHE_RSA_WITH_AES_128_CBC_SHA },
{ TLS_DHE_RSA_WITH_AES_256_CBC_SHA },
/* 3.3.1.2 Cipher Suites for TLS 1.3 */
{ TLS_AES_128_GCM_SHA256 },
{ TLS_AES_256_GCM_SHA384 },
};
S2N_RESULT s2n_fips_validate_cipher_suite(const struct s2n_cipher_suite *cipher_suite, bool *valid)
{
RESULT_ENSURE_REF(cipher_suite);
RESULT_ENSURE_REF(valid);
*valid = false;
for (size_t i = 0; i < s2n_array_len(fips_cipher_suite_ianas); i++) {
if (fips_cipher_suite_ianas[i][0] != cipher_suite->iana_value[0]) {
continue;
}
if (fips_cipher_suite_ianas[i][1] != cipher_suite->iana_value[1]) {
continue;
}
*valid = true;
return S2N_RESULT_OK;
}
return S2N_RESULT_OK;
}
S2N_RESULT s2n_fips_validate_signature_scheme(const struct s2n_signature_scheme *sig_alg, bool *valid)
{
RESULT_ENSURE_REF(sig_alg);
RESULT_GUARD(s2n_fips_validate_hash_algorithm(sig_alg->hash_alg, valid));
return S2N_RESULT_OK;
}
/* https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Ar3.pdf */
const struct s2n_ecc_named_curve *fips_curves[] = {
&s2n_ecc_curve_secp256r1,
&s2n_ecc_curve_secp384r1,
&s2n_ecc_curve_secp521r1,
};
S2N_RESULT s2n_fips_validate_curve(const struct s2n_ecc_named_curve *curve, bool *valid)
{
RESULT_ENSURE_REF(curve);
RESULT_ENSURE_REF(valid);
*valid = false;
for (size_t i = 0; i < s2n_array_len(fips_curves); i++) {
if (fips_curves[i] == curve) {
*valid = true;
return S2N_RESULT_OK;
}
}
return S2N_RESULT_OK;
}
/* https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf */
const struct s2n_kem *fips_kems[] = {
&s2n_mlkem_768,
&s2n_mlkem_1024
};
S2N_RESULT s2n_fips_validate_kem(const struct s2n_kem *kem, bool *valid)
{
RESULT_ENSURE_REF(kem);
RESULT_ENSURE_REF(valid);
*valid = false;
for (size_t i = 0; i < s2n_array_len(fips_kems); i++) {
if (fips_kems[i] == kem) {
*valid = true;
return S2N_RESULT_OK;
}
}
return S2N_RESULT_OK;
}
S2N_RESULT s2n_fips_validate_hybrid_group(const struct s2n_kem_group *hybrid_group, bool *valid)
{
RESULT_ENSURE_REF(hybrid_group);
RESULT_ENSURE_REF(valid);
*valid = false;
/* The first share in a Hybrid Group must be FIPS-approved, see page 33 of NIST 800-56Cr2.
*
* "Recommendation is expanded to permit the use of “hybrid” shared secrets of the form Z' = Z || T,
* which is a concatenation consisting of a “standard” shared secret Z that was generated during the
* execution of a key-establishment scheme as currently specified in [SP 800-56A] or [SP 800-56B],
* followed by an auxiliary shared secret T that has been generated using some other method."
*
* https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Cr2.pdf
*/
if (hybrid_group->send_kem_first) {
RESULT_GUARD(s2n_fips_validate_kem(hybrid_group->kem, valid));
} else {
RESULT_GUARD(s2n_fips_validate_curve(hybrid_group->curve, valid));
}
return S2N_RESULT_OK;
}
S2N_RESULT s2n_fips_validate_version(uint8_t version, bool *valid)
{
RESULT_ENSURE_REF(valid);
/* Technically FIPS 140-3 still allows TLS1.0 and TLS1.1 for some use cases,
* but for simplicity s2n-tls does not.
*/
*valid = (version >= S2N_TLS12);
return S2N_RESULT_OK;
}
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