Implemented P2P traffic encryption.

Changed serialization format of P2P messages.
Refactored P2P network code.

src/crypto/chacha.rs

@@ -0,0 +1,66 @@
+use chacha20poly1305::{ChaCha20Poly1305, Key, Nonce};
+use chacha20poly1305::aead::{Aead, NewAead};
+use std::fmt::{Debug, Formatter};
+use std::fmt;
+
+pub const ZERO_NONCE: [u8; 12] = [0u8; 12];
+const FAILURE: &str = "encryption failure!";
+
+/// A small wrap-up to use Chacha20 encryption for domain names.
+#[derive(Clone)]
+pub struct Chacha {
+    cipher: ChaCha20Poly1305,
+    nonce: [u8; 12]
+}
+
+impl Chacha {
+    pub fn new(key: &[u8], nonce: &[u8]) -> Self {
+        let key = Key::from_slice(key);
+        let cipher = ChaCha20Poly1305::new(key);
+        let mut buf = [0u8; 12];
+        buf.copy_from_slice(nonce);
+        Chacha { cipher, nonce: buf }
+    }
+
+    pub fn encrypt(&self, data: &[u8]) -> Vec<u8> {
+        let nonce = Nonce::from(self.nonce.clone());
+        self.cipher.encrypt(&nonce, data.as_ref()).expect(FAILURE)
+    }
+
+    pub fn decrypt(&self, data: &[u8]) -> Vec<u8> {
+        let nonce = Nonce::from(self.nonce.clone());
+        self.cipher.decrypt(&nonce, data.as_ref()).expect(FAILURE)
+    }
+
+    pub fn get_nonce(&self) -> &[u8; 12] {
+        &self.nonce
+    }
+}
+
+impl Debug for Chacha {
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
+        fmt.write_str("ChaCha20Poly1305")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::crypto::Chacha;
+    use crate::{to_hex};
+
+    #[test]
+    pub fn test_chacha() {
+        let buf = b"178135D209C697625E3EC71DA5C760382E54936F824EE5083908DA66B14ECE18";
+        let chacha1 = Chacha::new(b"178135D209C697625E3EC71DA5C76038", &buf[..12]);
+        let bytes1 = chacha1.encrypt(b"TEST");
+        println!("{}", to_hex(&bytes1));
+
+        let chacha2 = Chacha::new(b"178135D209C697625E3EC71DA5C76038", &buf[..12]);
+        let bytes2 = chacha2.decrypt(&bytes1);
+        assert_eq!(String::from_utf8(bytes2).unwrap(), "TEST");
+
+        let bytes2 = chacha2.encrypt(b"TEST");
+
+        assert_eq!(bytes1, bytes2);
+    }
+}

src/crypto/mod.rs

@@ -1,3 +1,6 @@
 mod crypto_box;
+mod chacha;
 
-pub use crypto_box::CryptoBox;
+pub use crypto_box::CryptoBox;
+pub use chacha::Chacha;
+pub use chacha::ZERO_NONCE;