diff --git a/proxy/shadowsocks2022/method_aes128gcm.go b/proxy/shadowsocks2022/method_aes128gcm.go
index 5d2d8c8d070..17b0d9904f0 100644
--- a/proxy/shadowsocks2022/method_aes128gcm.go
+++ b/proxy/shadowsocks2022/method_aes128gcm.go
@@ -62,6 +62,9 @@ func (a AES128GCMMethod) GetUDPClientProcessor(ipsk [][]byte, psk []byte, deriva
 		}
 		return aead
 	}
+	if len(ipsk) == 0 {
+		return NewAESUDPClientPacketProcessor(reqSeparateHeaderCipher, respSeparateHeaderCipher, getPacketAEAD, nil), nil
+	}
 	eihGenerator := newAESEIHGeneratorContainer(len(ipsk), psk, ipsk)
 	getEIH := func(mask []byte) ExtensibleIdentityHeaders {
 		eih, err := eihGenerator.GenerateEIHUDP(derivation, a, mask)
diff --git a/proxy/shadowsocks2022/method_aes256gcm.go b/proxy/shadowsocks2022/method_aes256gcm.go
index 064ff3b8ee7..26820dc523e 100644
--- a/proxy/shadowsocks2022/method_aes256gcm.go
+++ b/proxy/shadowsocks2022/method_aes256gcm.go
@@ -62,6 +62,9 @@ func (a AES256GCMMethod) GetUDPClientProcessor(ipsk [][]byte, psk []byte, deriva
 		}
 		return aead
 	}
+	if len(ipsk) == 0 {
+		return NewAESUDPClientPacketProcessor(reqSeparateHeaderCipher, respSeparateHeaderCipher, getPacketAEAD, nil), nil
+	}
 	eihGenerator := newAESEIHGeneratorContainer(len(ipsk), psk, ipsk)
 	getEIH := func(mask []byte) ExtensibleIdentityHeaders {
 		eih, err := eihGenerator.GenerateEIHUDP(derivation, a, mask)