diff --git a/DES.py b/DES.py
index 4dd9adf..d5467b4 100644
--- a/DES.py
+++ b/DES.py
@@ -98,14 +98,76 @@ sbox = [[[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7],
          [7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8],
          [2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]]]
 
+LEFT_SHIFT = [
+    1, 1, 2, 2, 2, 2, 2, 2,
+    1, 2, 2, 2, 2, 2, 2, 1
+]
+
+subkeys = []
+
+def hex_to_binary(hex):
+    return bin(int(hex, 16))[2:].zfill(64)
+
+
+def DES_Encrypt(data_block, key):
+
+    data_block = hex_to_binary(data_block)
+    key = hex_to_binary(key)
+
+    print ("binary key:", key)
+
+    key = permute(key, PC1)
+    print ("permutated key:", key)
+
+    # generate 16 subkeys 
+    left_key = key[:28]
+    right_key = key[28:]
+
+    # left shift
+    for i in range(16):
+        left_key = left_key[LEFT_SHIFT[i]:] + left_key[:LEFT_SHIFT[i]]
+        right_key = right_key[LEFT_SHIFT[i]:] + right_key[:LEFT_SHIFT[i]]
+        subkeys.append(permute(left_key + right_key, PC2))
+        print ("subkey: ", "K", i+1, subkeys[i])
+        #
+
+    # # Initial Permutation
+    # data_block = permute(data_block, IP)
+
+    # # Split data_block into left and right halves
+    # left_half = data_block[:28]
+    # right_half = data_block[28:]
+
+    print ("left key:",left_key)
+    print ("right key:",right_key)
+
+#     # Generate 16 subkeys
+#     subkeys = generate_subkeys(key)
+
+#     # Perform 16 rounds of DES
+#     for i in range(16):
+#         new_left_half = right_half
+#         right_half = xor(left_half, f(right_half, subkeys[i]))
+#         left_half = new_left_half
+
+#     # Combine the left and right halves
+#     data_block = left_half + right_half
+
+#     # Final Permutation
+#     data_block = permute(data_block, FP)
+
+#     return data_block
+
+def permute(data_block, permutation):
+    return [data_block[i - 1] for i in permutation]
+
+#def generate_subkeys(key):
 
 
 
 
-def DES_Encrypt(data_block, key, operation):
-
-
-        
+def DES_Decrypt(data_block, key):
+    pass
 
 
 def parse_variables(file_path):
@@ -122,10 +184,19 @@ def parse_variables(file_path):
         print(f"Error: The file {file_path} was not found.")
     return variables
 
+def output(output_file, data_block):
+    with open(output_file, 'w') as file:
+        for subkeys in subkeys:
+            file.write("K", subkeys)
+
+        file.write(data_block)
+
+
 def main():
     # Set up command-line argument parsing
     parser = argparse.ArgumentParser(description='Parse variables for encryption or decryption.')
-    parser.add_argument('file', type=str, help='Path to the text file containing the variables.')
+    parser.add_argument(' input_file', type=str, help='Path to the text file containing the variables.')
+    parser.add_argument(' output_file', type=str, help='Path to the text file containing the output.')
 
     # Parse the arguments
     args = parser.parse_args()
@@ -133,6 +204,9 @@ def main():
     # Parse the file and retrieve variables
     variables = parse_variables(args.file)
 
+    # path to output file
+    output_file = args.output_file
+
     # Get data_block and key from the parsed variables
     data_block = variables.get('data_block', '')
     key = variables.get('key', '')
@@ -142,8 +216,12 @@ def main():
     print(f"Data Block: {data_block}")
     print(f"Key: {key}")
     print(f"Operation: {operation}")
+    if operation == 'encryption' :
 
-    DES_Encrypt(data_block, key, operation)
+        DES_Encrypt(data_block, key)
+
+    else : 
+        DES_Decrypt(data_block, key)
 
 if __name__ == "__main__":
     main()
\ No newline at end of file