diff --git a/des/rtl/verilog/des_pkg.v b/des/rtl/verilog/des_pkg.v
index 3ebfe96..b8a4191 100644
--- a/des/rtl/verilog/des_pkg.v
+++ b/des/rtl/verilog/des_pkg.v
@@ -60,3 +60,75 @@ begin
 end
 endfunction
 
+
+function [0:3] s1 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'hE4D12FB83A6C5907_0F74E2D1A6CB9538_41E8D62BFC973A50_FC8249175B3EA06D;
+  s1 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s2 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'hF18E6B34972DC05A_3D47F28DC01A69B5_0E7BA4D158C6932F_D8A13F42B67C05E9;
+  s2 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s3 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'hA09E63F51DC7B428_D709346A285ECBF1_D6498F30B12C5AE7_1AD069874FE3B52C;
+  s3 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s4 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'h7DE3069A1285BC4F_D8B56F03472C1AE9_A690CB7DF13E5284_3F06A1D8945BC72E;
+  s4 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s5 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'h2C417AB6853FD0E9_EB2C47D150FA3986_421BAD78F9C5630E_B8C71E2D6F09A453;
+  s5 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s6 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'hC1AF92680D34E75B_AF427C9561DE0B38_9EF528C3704A1DB6_432C95FABE17608D;
+  s6 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s7 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'h4B2EF08D3C975A61_D0B7491AE35C2F86_14BDC37EAF680592_6BD814A7950FE23C;
+  s7 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+
+
+function [0:3] s8 (input [0:5] data);
+  reg [0:255] matrix;
+begin
+  matrix = 256'hD2846FB1A93E50C7_1FD8A374C56B0E92_7B419CE206ADF358_21E74A8DFC90356B;
+  s8 = matrix[{data[0],data[5]}*16 + data[1:4]];
+end
+endfunction
+