/*
 * SPDX-License-Identifier: LicenseRef-CSSL-1.0
 */

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "aes_128_cbc_cmac.h"

#include "common/utils/assertions.h"
#include <openssl/cmac.h>

#if OPENSSL_VERSION_MAJOR >= 3
// code for version 3.0 or greater
#include <openssl/core_names.h>

cbc_cmac_ctx_t init_aes_128_cbc_cmac(const uint8_t key[16])
{
  DevAssert(key != NULL);

  /* Fetch the CMAC implementation */
  EVP_MAC *mac_implementation = EVP_MAC_fetch(NULL, "CMAC", NULL);
  DevAssert(mac_implementation != NULL);

  /* Create a context for the CMAC operation */
  EVP_MAC_CTX* mac_context = EVP_MAC_CTX_new(mac_implementation);
  DevAssert(mac_context != NULL);

  cbc_cmac_ctx_t ctx = { .mac_implementation = mac_implementation, .mac_context = mac_context };
  memcpy(ctx.key, key, 16);

  // The underlying cipher to be used
  char cipher_name[] = "aes128";

  OSSL_PARAM params[2] = {0};
  params[0] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_CIPHER, cipher_name,
                                               sizeof(cipher_name));
  params[1] = OSSL_PARAM_construct_end();

  /* Initialise the CMAC operation */
  int rc = EVP_MAC_init(mac_context, key, 16, params);
  DevAssert(rc != 0);

  return ctx;
}

void cipher_aes_128_cbc_cmac(cbc_cmac_ctx_t const* ctx, const aes_128_t* k_iv, byte_array_t msg, size_t len_out, uint8_t out[len_out])
{
  DevAssert(ctx != NULL);
  DevAssert(k_iv != NULL);

  /* reset the CMAC */
  /* There is a bug with version <= 3.0.2 of OpenSSL for which we must
   * pass the key to reset. (Some Ubuntu version provide this version.)
   * Passing the key has some impact on performance.
   * todo: drop support for old versions of openssl.
   */
#if OPENSSL_VERSION_NUMBER <= 0x30000020
  /* todo: when/if we remove this code, don't forget to check use of k_iv->key
   * somewhere else in the codebase.
   * If not used, remove from aes_128_t*
   */
  int rc = EVP_MAC_init(ctx->mac_context, k_iv->key, 16, NULL);
#else
  int rc = EVP_MAC_init(ctx->mac_context, NULL, 0, NULL);
#endif
  DevAssert(rc != 0);

  size_t sz_iv = 0;
  uint8_t* iv = NULL;
  if(k_iv->type == AES_INITIALIZATION_VECTOR_8){
    sz_iv = 8;
    iv = (uint8_t*)k_iv->iv8.iv;
  } else if(k_iv->type == AES_INITIALIZATION_VECTOR_16) {
    sz_iv = 16;
    iv = (uint8_t*)k_iv->iv16.iv;
  } else {
    DevAssert(0!=0 && "Unknwon Initialization vector");
  }

  /* Make one or more calls to process the data to be authenticated */
  rc = EVP_MAC_update(ctx->mac_context, iv, sz_iv);
  DevAssert(rc != 0);

  /* Make one or more calls to process the data to be authenticated */
  rc = EVP_MAC_update(ctx->mac_context, msg.buf, msg.len);
  DevAssert(rc != 0);

  /* Make a call to the final with a NULL buffer to get the length of the MAC */
  size_t out_len = 0;
  rc = EVP_MAC_final(ctx->mac_context, out, &out_len, len_out);
  DevAssert(rc != 0);
}

void free_aes_128_cbc_cmac(cbc_cmac_ctx_t const* ctx)
{
  DevAssert(ctx != NULL);
  EVP_MAC_CTX_free(ctx->mac_context);
  EVP_MAC_free(ctx->mac_implementation);
}

#else
// code for 1.1.x or lower

cbc_cmac_ctx_t init_aes_128_cbc_cmac(const uint8_t key[16])
{
  DevAssert(key != NULL);
  cbc_cmac_ctx_t ctx = {.mac_implementation = NULL, .mac_context = NULL };

  ctx.mac_context = CMAC_CTX_new();
  DevAssert(ctx.mac_context != NULL);

  //assert(16 == sizeof(ctx.key));
  memcpy(ctx.key, key, 16); //sizeof(ctx.key));

  CMAC_Init(ctx.mac_context, ctx.key, 16, EVP_aes_128_cbc(), NULL);
  return ctx;
}

void cipher_aes_128_cbc_cmac(cbc_cmac_ctx_t const* ctx, const aes_128_t* k_iv, byte_array_t msg, size_t len_out, uint8_t out[len_out])
{
  DevAssert(ctx != NULL);
  DevAssert(k_iv != NULL);

  //From https://man.openbsd.org/CMAC_Init.3
  //If ctx is already initialized, CMAC_Init() can be called again with key,
  //cipher, and impl all set to NULL and key_len set to 0. In that case, any
  //data already processed is discarded and ctx is re-initialized to start
  //reading data anew.
  CMAC_Init(ctx->mac_context, NULL, 0, NULL, NULL);

  size_t sz_iv = 0;
  uint8_t* iv = NULL;
  if(k_iv->type == AES_INITIALIZATION_VECTOR_8){
    sz_iv = 8;
    iv = (uint8_t*)k_iv->iv8.iv;
  } else if(k_iv->type == AES_INITIALIZATION_VECTOR_16) {
    sz_iv = 16;
    iv = (uint8_t*)k_iv->iv16.iv;
  } else {
    AssertFatal(0 != 0, "Unknwon Initialization vector");
  }

  CMAC_Update(ctx->mac_context, iv, sz_iv);

  CMAC_Update(ctx->mac_context, msg.buf, msg.len);
  size_t len_res = 0;
  CMAC_Final(ctx->mac_context, out, &len_res);
  DevAssert(len_res <= len_out);
}

void free_aes_128_cbc_cmac(cbc_cmac_ctx_t const* ctx)
{
  DevAssert(ctx != NULL);
  CMAC_CTX_free(ctx->mac_context);
}

#endif
