diff --git a/pixel.cpp b/pixel.cpp
index cc8d0d46676811ce87e6244304c21f896a4a2f8f..2703e9e67b20087ffd33bfe2285de0323cd79e8c 100644
--- a/pixel.cpp
+++ b/pixel.cpp
@@ -17,7 +17,8 @@ int convertBinInt(long long n);
 void decrypt(int data);
 
 
-void pixel(ap_int<32> selector,
+void pixel(char* key;
+        ap_int<32> selector,
 		ap_int<32> position1,
 		ap_int<32> position2,
 		ap_int<32> stream_count,
@@ -26,6 +27,7 @@ void pixel(ap_int<32> selector,
 		hls::stream< pkt_t > &dout
 ) {
 	#pragma HLS INTERFACE ap_ctrl_none port=return
+    #pragma HLS INTERFACE s_axilite port=key
     #pragma HLS INTERFACE s_axilite port=selector
 	#pragma HLS INTERFACE s_axilite port=position1
 	#pragma HLS INTERFACE s_axilite port=position2