install crypto_box & de-&encrypt messages in client.rs

Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+crypto_box = "0.8.2"

src/bin/client.rs

@@ -1,5 +1,9 @@
 use std::io::Write;
 use std::net::TcpStream;
+use crypto_box::{
+    aead::{Aead, AeadCore, OsRng},
+    SalsaBox, PublicKey, SecretKey
+};
 
 fn main() {
     //let stream = TcpStream::connect("172.30.16.1:8080");
@@ -15,9 +19,67 @@ fn main() {
                         if n == 0 {
                             break; // Beenden bei EOF
                         }
-                        println!("Sending {}", buffer);
+                        //
+                        // Encryption
+                        //
+
+                        // Generate a random secret key.
+                        // NOTE: The secret key bytes can be accessed by calling `secret_key.as_bytes()`
+                        let alice_secret_key = SecretKey::generate(&mut OsRng);
+
+                        // Get the public key for the secret key we just generated
+                        let alice_public_key_bytes = alice_secret_key.public_key().as_bytes().clone();
+
+                        // Obtain your recipient's public key.
+                        let bob_public_key = PublicKey::from([
+                            0xe8, 0x98, 0xc, 0x86, 0xe0, 0x32, 0xf1, 0xeb,
+                            0x29, 0x75, 0x5, 0x2e, 0x8d, 0x65, 0xbd, 0xdd,
+                            0x15, 0xc3, 0xb5, 0x96, 0x41, 0x17, 0x4e, 0xc9,
+                            0x67, 0x8a, 0x53, 0x78, 0x9d, 0x92, 0xc7, 0x54,
+                        ]);
+
+                        // Create a `SalsaBox` by performing Diffie-Hellman key agreement between
+                        // the two keys.
+                        let alice_box = SalsaBox::new(&bob_public_key, &alice_secret_key);
+
+                        // Get a random nonce to encrypt the message under
+                        let nonce = SalsaBox::generate_nonce(&mut OsRng);
+
+                        // Message to encrypt
+                        let plaintext = buffer.trim().as_bytes();
+
+                        // Encrypt the message using the box
+                        let ciphertext = alice_box.encrypt(&nonce, &plaintext[..]).expect("Fehler");
+
+                        println!("Sending {0} as {1:?}", buffer.trim(), plaintext);
                         stream.write(buffer.as_bytes()).unwrap();
-                        println!("Sent {}, awaiting reply ...", buffer);
+
+                        //
+                        // Decryption
+                        //
+
+                        // Either side can encrypt or decrypt messages under the Diffie-Hellman key
+                        // they agree upon. The example below shows Bob's side.
+                        let bob_secret_key = SecretKey::from([
+                            0xb5, 0x81, 0xfb, 0x5a, 0xe1, 0x82, 0xa1, 0x6f,
+                            0x60, 0x3f, 0x39, 0x27, 0xd, 0x4e, 0x3b, 0x95,
+                            0xbc, 0x0, 0x83, 0x10, 0xb7, 0x27, 0xa1, 0x1d,
+                            0xd4, 0xe7, 0x84, 0xa0, 0x4, 0x4d, 0x46, 0x1b
+                        ]);
+
+                        // Deserialize Alice's public key from bytes
+                        let alice_public_key = PublicKey::from(alice_public_key_bytes);
+
+                        // Bob can compute the same `SalsaBox` as Alice by performing the
+                        // key agreement operation.
+                        let bob_box = SalsaBox::new(&alice_public_key, &bob_secret_key);
+
+                        // Decrypt the message, using the same randomly generated nonce
+                        let decrypted_plaintext = bob_box.decrypt(&nonce, &ciphertext[..]).expect("Fehler");
+                        let dec_plain_plaintext = std::str::from_utf8(&*decrypted_plaintext).expect("Nö");
+                        assert_eq!(&plaintext[..], &decrypted_plaintext[..]);
+
+                        println!("Sent {0:?} as cypher: {1:?}, decrypted: {2:?}, {3}", plaintext, ciphertext, decrypted_plaintext, dec_plain_plaintext);
                     }
                     Err(error) => {
                         println!("error: {error}");