+/** \fn void aes_init(const void* key, uint16_t keysize_b, aes_genctx_t* ctx)
+ * \brief initialize the keyschedule
+ *
+ * This function computes the keyschedule from a given key with a given length
+ * and stores it in the context variable
+ * \param key pointer to the key material
+ * \param keysize_b length of the key in bits (valid are 128, 192 and 256)
+ * \param ctx pointer to the context where the keyschedule should be stored
+ */