/***************************************************************************
* Additional implementation of "BIKE: Bit Flipping Key Encapsulation". 
* Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Written by Nir Drucker and Shay Gueron
* AWS Cryptographic Algorithms Group
* (ndrucker@amazon.com, gueron@amazon.com)
*
* The license is detailed in the file LICENSE.md, and applies to this file.
* ***************************************************************************/

#pragma once

#include "cleanup.h"
#include <openssl/evp.h>

#define MAX_AES_INVOKATION (MASK(32))

#define AES256_KEY_SIZE (32ULL)
#define AES256_KEY_BITS (AES256_KEY_SIZE * 8)
#define AES256_BLOCK_SIZE (16ULL)
#define AES256_ROUNDS (14ULL)

typedef ALIGN(16) struct aes256_key_s {
        uint8_t raw[AES256_KEY_SIZE];
} aes256_key_t;

_INLINE_ void aes256_key_cleanup(aes256_key_t *o) 
{
    secure_clean(o->raw, sizeof(*o)); 
}

//Using OpenSSL structures
typedef EVP_CIPHER_CTX* aes256_ks_t;

_INLINE_ ret_t aes256_key_expansion(OUT aes256_ks_t *ks,
                                    IN const aes256_key_t *key)
{
    *ks = EVP_CIPHER_CTX_new();
    if(*ks == NULL)
    {
        BIKE_ERROR(EXTERNAL_LIB_ERROR_OPENSSL);
    }
    if(0 == EVP_EncryptInit_ex(*ks, EVP_aes_256_ecb(), NULL, key->raw, NULL))
    {
        EVP_CIPHER_CTX_free(*ks);
        BIKE_ERROR(EXTERNAL_LIB_ERROR_OPENSSL);
    }

    EVP_CIPHER_CTX_set_padding(*ks, 0);
    
    return SUCCESS;
}

_INLINE_ ret_t aes256_enc(OUT uint8_t *ct,
                          IN const uint8_t *pt,
                          IN const aes256_ks_t *ks)
{
    int outlen=0;
    if(0 == EVP_EncryptUpdate(*ks, ct, &outlen, pt, AES256_BLOCK_SIZE))
    {
        BIKE_ERROR(EXTERNAL_LIB_ERROR_OPENSSL);
    }
    return SUCCESS;
}


_INLINE_ void aes256_free_ks(OUT aes256_ks_t *ks)
{
    EVP_CIPHER_CTX_free(*ks);
    ks = NULL;
}