add fixme: enforce 8 byte length of Kc

Change-Id: I57efb0a24cb71b365189eccb5088b130fad15093
diff --git a/src/gsm/gsm0808_utils.c b/src/gsm/gsm0808_utils.c
index b5b8431..78cbe92 100644
--- a/src/gsm/gsm0808_utils.c
+++ b/src/gsm/gsm0808_utils.c
@@ -721,6 +721,8 @@
 	}
 
 	msgb_put_u8(msg, perm_algo);
+	/* FIXME: 48.008 3.2.2.10 Encryption Information says:
+	 * "When present, the key shall be 8 octets long." */
 	ptr = msgb_put(msg, ei->key_len);
 	memcpy(ptr, ei->key, ei->key_len);
 
@@ -760,6 +762,8 @@
 	}
 	ei->perm_algo_len = perm_algo_len;
 
+	/* FIXME: 48.008 3.2.2.10 Encryption Information says:
+	 * "When present, the key shall be 8 octets long." */
 	ei->key_len = len - 1;
 	memcpy(ei->key, elem, ei->key_len);
 	elem+=ei->key_len;