feat: add cli app

des/src/main.rs

@@ -0,0 +1,21 @@
+mod args;
+
+use crate::args::{Args, Operation};
+use clap::Parser;
+use des_lib::Des;
+
+fn main() {
+    let args = Args::parse();
+    let des = Des::new(args.key.as_64());
+
+    match args.operation {
+        Operation::Encrypt => {
+            let ciphertext = des.encrypt(args.text.as_64());
+            println!("{ciphertext:016X}");
+        }
+        Operation::Decrypt { output_format } => {
+            let plaintext = des.decrypt(args.text.as_64());
+            println!("{plaintext:016X}");
+        }
+    }
+}