Ox: Improve log messages.

ox.go

@@ -405,7 +405,7 @@ func oxGetPrivKey(jid string, passphrase string) (*crypto.Key, error) {
 	if passphrase != "" {
 		key, err = key.Unlock([]byte(passphrase))
 		if err != nil {
-			log.Fatal("Couldn't unlock private key.")
+			log.Fatal("Ox: couldn't unlock private key.")
 		}
 	}
 	isLocked, err := key.IsLocked()
@@ -413,10 +413,10 @@ func oxGetPrivKey(jid string, passphrase string) (*crypto.Key, error) {
 		return nil, err
 	}
 	if isLocked {
-		log.Fatal("Private key is locked.")
+		log.Fatal("Ox: private key is locked.")
 	}
 	if key.IsExpired() {
-		return nil, errors.New("Key is expired: " + key.GetFingerprint())
+		return nil, errors.New("Ox: private key is expired: " + key.GetFingerprint())
 	}
 	return key, nil
 }