#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>

#include "secu_defs.h"

#include <openssl/aes.h>
#include <openssl/cmac.h>
#include <openssl/evp.h>

#include "assertions.h"
#include "conversions.h"

// #define SECU_DEBUG

/*!
 * @brief Create integrity cmac t for a given message.
 * @param[in] stream_cipher Structure containing various variables to setup encoding
 * @param[out] out For EIA2 the output string is 32 bits long
 */
int nas_stream_encrypt_eia2(nas_stream_cipher_t *stream_cipher, uint8_t out[4])
{
    uint8_t  *m;
    uint32_t local_count;
    size_t size = 4;

    uint8_t  data[16];

    CMAC_CTX *cmac_ctx;

    uint32_t zero_bit = 0;
    uint32_t m_length;

    DevAssert(stream_cipher != NULL);
    DevAssert(stream_cipher->key != NULL);
    DevAssert(out != NULL);

    memset(data, 0, 16);

    zero_bit = stream_cipher->blength & 0x7;

    m_length = stream_cipher->blength >> 3;
    if (zero_bit > 0)
        m_length += 1;

    local_count = hton_int32(stream_cipher->count);

    m = calloc(m_length + 8, sizeof(uint8_t));

    memcpy(&m[0], &local_count, 4);
    m[4] = ((stream_cipher->bearer & 0x1F) << 3) | ((stream_cipher->direction & 0x01) << 2);

    memcpy(&m[8], stream_cipher->message, m_length);

#if defined(SECU_DEBUG)
    {
        int i;
        printf("Byte length: %u, Zero bits: %u\nm: ", m_length + 8, zero_bit);
        for (i = 0; i < m_length + 8; i++)
            printf("%02x", m[i]);
        printf("\n");
    }
#endif

    cmac_ctx = CMAC_CTX_new();

    CMAC_Init(cmac_ctx, stream_cipher->key, stream_cipher->key_length, EVP_aes_128_cbc(), NULL);
    CMAC_Update(cmac_ctx, m, m_length + 8);

    CMAC_Final(cmac_ctx, data, &size);

    CMAC_CTX_free(cmac_ctx);

#if defined(SECU_DEBUG)
    {
        int i;
        printf("out: ");
        for (i = 0; i < 16; i++)
            printf("%02x", data[i]);
        printf("\n");
    }
#endif

    memcpy(out, data, 4);
    free(m);

    return 0;
}