diff --git a/include/osmocom/crypt/gprs_cipher.h b/include/osmocom/crypt/gprs_cipher.h
index 940b07b..d6edefa 100644
--- a/include/osmocom/crypt/gprs_cipher.h
+++ b/include/osmocom/crypt/gprs_cipher.h
@@ -9,6 +9,7 @@
 	GPRS_ALGO_GEA1,
 	GPRS_ALGO_GEA2,
 	GPRS_ALGO_GEA3,
+	GPRS_ALGO_GEA4,
 	_GPRS_ALGO_NUM
 };
 
@@ -27,7 +28,7 @@
 	/* As specified in 04.64 Annex A.  Uses Kc, IV and direction
 	 * to generate the 1523 bytes cipher stream that need to be
 	 * XORed wit the plaintext for encrypt / ciphertext for decrypt */
-	int (*run)(uint8_t *out, uint16_t len, uint64_t kc, uint32_t iv,
+	int (*run)(uint8_t *out, uint16_t len, uint8_t *kc, uint32_t iv,
 		   enum gprs_cipher_direction direction);
 };
 
@@ -39,11 +40,14 @@
 
 /* function to be called by core code */
 int gprs_cipher_run(uint8_t *out, uint16_t len, enum gprs_ciph_algo algo,
-		    uint64_t kc, uint32_t iv, enum gprs_cipher_direction dir);
+		    uint8_t *kc, uint32_t iv, enum gprs_cipher_direction dir);
 
 /* Do we have an implementation for this cipher? */
 int gprs_cipher_supported(enum gprs_ciph_algo algo);
 
+/* Return key length for supported cipher, in bytes */
+unsigned gprs_cipher_key_length(enum gprs_ciph_algo algo);
+
 /* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
 uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc);