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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/aes.h>
#include "crypto/s2n_cipher.h"
#include "crypto/s2n_openssl.h"
#include "error/s2n_errno.h"
#include "utils/s2n_blob.h"
#include "utils/s2n_safety.h"
static uint8_t s2n_cbc_cipher_aes128_available()
{
return (EVP_aes_128_cbc() ? 1 : 0);
}
static uint8_t s2n_cbc_cipher_aes256_available()
{
return (EVP_aes_256_cbc() ? 1 : 0);
}
static int s2n_cbc_cipher_aes_encrypt(struct s2n_session_key *key, struct s2n_blob *iv, struct s2n_blob *in, struct s2n_blob *out)
{
POSIX_ENSURE_GTE(out->size, in->size);
POSIX_GUARD_OSSL(EVP_EncryptInit_ex(key->evp_cipher_ctx, NULL, NULL, NULL, iv->data), S2N_ERR_KEY_INIT);
/* len is set by EVP_EncryptUpdate and checked post operation */
int len = 0;
POSIX_GUARD_OSSL(EVP_EncryptUpdate(key->evp_cipher_ctx, out->data, &len, in->data, in->size), S2N_ERR_ENCRYPT);
POSIX_ENSURE((int64_t) len == (int64_t) in->size, S2N_ERR_ENCRYPT);
return 0;
}
int s2n_cbc_cipher_aes_decrypt(struct s2n_session_key *key, struct s2n_blob *iv, struct s2n_blob *in, struct s2n_blob *out)
{
POSIX_ENSURE_GTE(out->size, in->size);
POSIX_GUARD_OSSL(EVP_DecryptInit_ex(key->evp_cipher_ctx, NULL, NULL, NULL, iv->data), S2N_ERR_KEY_INIT);
/* len is set by EVP_DecryptUpdate. It is not checked here but padding is manually removed and therefore
* the decryption operation is validated. */
int len = 0;
POSIX_GUARD_OSSL(EVP_DecryptUpdate(key->evp_cipher_ctx, out->data, &len, in->data, in->size), S2N_ERR_DECRYPT);
return 0;
}
int s2n_cbc_cipher_aes128_set_decryption_key(struct s2n_session_key *key, struct s2n_blob *in)
{
POSIX_ENSURE_EQ(in->size, 128 / 8);
/* Always returns 1 */
EVP_CIPHER_CTX_set_padding(key->evp_cipher_ctx, 0);
POSIX_GUARD_OSSL(EVP_DecryptInit_ex(key->evp_cipher_ctx, EVP_aes_128_cbc(), NULL, in->data, NULL), S2N_ERR_KEY_INIT);
return 0;
}
static int s2n_cbc_cipher_aes128_set_encryption_key(struct s2n_session_key *key, struct s2n_blob *in)
{
POSIX_ENSURE_EQ(in->size, 128 / 8);
EVP_CIPHER_CTX_set_padding(key->evp_cipher_ctx, 0);
POSIX_GUARD_OSSL(EVP_EncryptInit_ex(key->evp_cipher_ctx, EVP_aes_128_cbc(), NULL, in->data, NULL), S2N_ERR_KEY_INIT);
return 0;
}
static int s2n_cbc_cipher_aes256_set_decryption_key(struct s2n_session_key *key, struct s2n_blob *in)
{
POSIX_ENSURE_EQ(in->size, 256 / 8);
EVP_CIPHER_CTX_set_padding(key->evp_cipher_ctx, 0);
POSIX_GUARD_OSSL(EVP_DecryptInit_ex(key->evp_cipher_ctx, EVP_aes_256_cbc(), NULL, in->data, NULL), S2N_ERR_KEY_INIT);
return 0;
}
int s2n_cbc_cipher_aes256_set_encryption_key(struct s2n_session_key *key, struct s2n_blob *in)
{
POSIX_ENSURE_EQ(in->size, 256 / 8);
EVP_CIPHER_CTX_set_padding(key->evp_cipher_ctx, 0);
POSIX_GUARD_OSSL(EVP_EncryptInit_ex(key->evp_cipher_ctx, EVP_aes_256_cbc(), NULL, in->data, NULL), S2N_ERR_KEY_INIT);
return 0;
}
static int s2n_cbc_cipher_aes_init(struct s2n_session_key *key)
{
s2n_evp_ctx_init(key->evp_cipher_ctx);
return 0;
}
static int s2n_cbc_cipher_aes_destroy_key(struct s2n_session_key *key)
{
EVP_CIPHER_CTX_cleanup(key->evp_cipher_ctx);
return 0;
}
const struct s2n_cipher s2n_aes128 = {
.key_material_size = 16,
.type = S2N_CBC,
.io.cbc = {
.block_size = 16,
.record_iv_size = 16,
.decrypt = s2n_cbc_cipher_aes_decrypt,
.encrypt = s2n_cbc_cipher_aes_encrypt },
.is_available = s2n_cbc_cipher_aes128_available,
.init = s2n_cbc_cipher_aes_init,
.set_decryption_key = s2n_cbc_cipher_aes128_set_decryption_key,
.set_encryption_key = s2n_cbc_cipher_aes128_set_encryption_key,
.destroy_key = s2n_cbc_cipher_aes_destroy_key,
};
const struct s2n_cipher s2n_aes256 = {
.key_material_size = 32,
.type = S2N_CBC,
.io.cbc = {
.block_size = 16,
.record_iv_size = 16,
.decrypt = s2n_cbc_cipher_aes_decrypt,
.encrypt = s2n_cbc_cipher_aes_encrypt },
.is_available = s2n_cbc_cipher_aes256_available,
.init = s2n_cbc_cipher_aes_init,
.set_decryption_key = s2n_cbc_cipher_aes256_set_decryption_key,
.set_encryption_key = s2n_cbc_cipher_aes256_set_encryption_key,
.destroy_key = s2n_cbc_cipher_aes_destroy_key,
};
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