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#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <nettle/nettle-meta.h>
#include <nettle/aes.h>
#include <nettle/ctr.h>
#include "assertions.h"
#include "conversions.h"
#include "secu_defs.h"
// #define SECU_DEBUG
int nas_stream_encrypt_eea2(nas_stream_cipher_t *stream_cipher, uint8_t **out)
{
uint8_t m[16];
uint32_t local_count;
void *ctx;
uint8_t *data;
uint32_t zero_bit = 0;
uint32_t byte_length;
DevAssert(stream_cipher != NULL);
DevAssert(out != NULL);
zero_bit = stream_cipher->blength & 0x7;
byte_length = stream_cipher->blength >> 3;
if (zero_bit > 0)
byte_length += 1;
ctx = malloc(nettle_aes128.context_size);
data = malloc(byte_length);
local_count = hton_int32(stream_cipher->count);
memset(m, 0, sizeof(m));
memcpy(&m[0], &local_count, 4);
m[4] = ((stream_cipher->bearer & 0x1F) << 3) |
((stream_cipher->direction & 0x01) << 2);
/* Other bits are 0 */
#if defined(SECU_DEBUG)
{
int i;
printf("Blength: %u, Zero bits: %u\n", stream_cipher->blength, zero_bit);
for (i = 0; i < sizeof(m); i++)
printf("0x%02x ", m[i]);
printf("\n");
}
#endif
nettle_aes128.set_encrypt_key(ctx, stream_cipher->key_length,
stream_cipher->key);
nettle_ctr_crypt(ctx, nettle_aes128.encrypt,
nettle_aes128.block_size, m,
byte_length, data, stream_cipher->message);
if (zero_bit > 0)
data[byte_length - 1] = data[byte_length - 1] & (uint8_t)(0xFF << (8 - zero_bit));
*out = data;
free(ctx);
return 0;
}