* @param key_bits 128, 192 or 256
* @param decrypt 0 for encryption, 1 for decryption
*/
-int av_aes_init(struct AVAES *a, uint8_t *key, int key_bits, int decrypt);
+int av_aes_init(struct AVAES *a, const uint8_t *key, int key_bits, int decrypt);
/**
* encrypts / decrypts.