themis_status_t secure_session_wrap(secure_session_t *session_ctx, const void *message, size_t message_length, void *wrapped_message, size_t *wrapped_message_length)
{
uint32_t *session_id = (uint32_t *)wrapped_message;
uint8_t *iv = (uint8_t *)(session_id + 1);
uint32_t *length = (uint32_t *)(iv + CIPHER_MAX_BLOCK_SIZE);
uint32_t *seq = length + 1;
uint8_t *ts = (uint8_t *)(seq + 1);
uint64_t curr_time;
themis_status_t res;
if ((NULL == session_ctx) || (NULL == message) || (0 == message_length) || (NULL == wrapped_message_length))
{
return THEMIS_INVALID_PARAMETER;
}
if ((NULL == wrapped_message) || (WRAPPED_SIZE(message_length) > *wrapped_message_length))
{
*wrapped_message_length = WRAPPED_SIZE(message_length);
return THEMIS_BUFFER_TOO_SMALL;
}
curr_time = time(NULL);
if (-1 == curr_time)
{
return THEMIS_FAIL;
}
*((uint64_t *)ts) = htobe64(curr_time);
*wrapped_message_length = WRAPPED_SIZE(message_length);
memmove(ts + 8, message, message_length);
*seq = htonl(session_ctx->out_seq);
*length = htonl(message_length + sizeof(uint32_t) + sizeof(uint64_t));
res = soter_rand(iv, CIPHER_MAX_BLOCK_SIZE);
if (THEMIS_SUCCESS != res)
{
return res;
}
res = encrypt_gcm(session_ctx->out_cipher_key, sizeof(session_ctx->out_cipher_key), iv, CIPHER_MAX_BLOCK_SIZE, length, message_length + sizeof(uint32_t) + sizeof(uint64_t) + sizeof(uint32_t), length, message_length + sizeof(uint32_t) + sizeof(uint64_t) + sizeof(uint32_t) + CIPHER_AUTH_TAG_SIZE);
if (THEMIS_SUCCESS != res)
{
return res;
}
*session_id = htonl(session_ctx->session_id);
session_ctx->out_seq++;
return THEMIS_SUCCESS;
}
void encrypt_box(uint8_t *keys, box *outer, size_t len) {
box *inner = (box *) outer->data;
uint8_t *outer_key = keys;
uint8_t *inner_key = keys + BOX_KEY_LEN;
randombytes(outer->iv, BOX_IV_LEN);
randombytes(inner->iv, BOX_IV_LEN);
uint8_t *data = inner->tag;
size_t inner_len = len + crypto_secretbox_ZEROBYTES;
memset(data, 0, crypto_secretbox_ZEROBYTES);
assert(crypto_secretbox(data, data, inner_len, inner->iv, inner_key) == 0);
encrypt_gcm(outer_key, outer->iv, outer->data, sizeof(box) + len, outer->tag);
}
