feat(tls): implement TLS certificate management and rotation

server/crates/arbiter-server/src/crypto/aead.rs

@@ -0,0 +1,139 @@
+use chacha20poly1305::{
+    aead::{Aead, KeyInit},
+    ChaCha20Poly1305, Key, Nonce,
+};
+
+use super::CryptoError;
+
+/// Encrypt plaintext with AEAD (ChaCha20Poly1305)
+///
+/// Returns (ciphertext, tag) on success
+pub fn encrypt(
+    plaintext: &[u8],
+    key: &[u8; 32],
+    nonce: &[u8; 12],
+) -> Result<Vec<u8>, CryptoError> {
+    let cipher_key = Key::from_slice(key);
+    let cipher = ChaCha20Poly1305::new(cipher_key);
+    let nonce_array = Nonce::from_slice(nonce);
+
+    cipher
+        .encrypt(nonce_array, plaintext)
+        .map_err(|e| CryptoError::AeadEncryption(e.to_string()))
+}
+
+/// Decrypt ciphertext with AEAD (ChaCha20Poly1305)
+///
+/// The ciphertext должен содержать tag (последние 16 bytes)
+pub fn decrypt(
+    ciphertext_with_tag: &[u8],
+    key: &[u8; 32],
+    nonce: &[u8; 12],
+) -> Result<Vec<u8>, CryptoError> {
+    let cipher_key = Key::from_slice(key);
+    let cipher = ChaCha20Poly1305::new(cipher_key);
+    let nonce_array = Nonce::from_slice(nonce);
+
+    cipher
+        .decrypt(nonce_array, ciphertext_with_tag)
+        .map_err(|e| CryptoError::AeadDecryption(e.to_string()))
+}
+
+/// Generate nonce from counter
+///
+/// Converts i32 counter to 12-byte nonce (big-endian encoding)
+pub fn nonce_from_counter(counter: i32) -> [u8; 12] {
+    let mut nonce = [0u8; 12];
+    nonce[8..12].copy_from_slice(&counter.to_be_bytes());
+    nonce
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_aead_encrypt_decrypt_round_trip() {
+        let plaintext = b"Hello, World! This is a secret message.";
+        let key = [42u8; 32];
+        let nonce = nonce_from_counter(1);
+
+        // Encrypt
+        let ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Verify ciphertext is different from plaintext
+        assert_ne!(ciphertext.as_slice(), plaintext);
+
+        // Decrypt
+        let decrypted = decrypt(&ciphertext, &key, &nonce).expect("Decryption failed");
+
+        // Verify round-trip
+        assert_eq!(decrypted.as_slice(), plaintext);
+    }
+
+    #[test]
+    fn test_aead_decrypt_with_wrong_key() {
+        let plaintext = b"Secret data";
+        let key = [1u8; 32];
+        let wrong_key = [2u8; 32];
+        let nonce = nonce_from_counter(1);
+
+        let ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Attempt decrypt with wrong key
+        let result = decrypt(&ciphertext, &wrong_key, &nonce);
+
+        // Should fail
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_aead_decrypt_with_wrong_nonce() {
+        let plaintext = b"Secret data";
+        let key = [1u8; 32];
+        let nonce = nonce_from_counter(1);
+        let wrong_nonce = nonce_from_counter(2);
+
+        let ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Attempt decrypt with wrong nonce
+        let result = decrypt(&ciphertext, &key, &wrong_nonce);
+
+        // Should fail
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_nonce_generation_from_counter() {
+        let nonce1 = nonce_from_counter(1);
+        let nonce2 = nonce_from_counter(2);
+        let nonce_max = nonce_from_counter(i32::MAX);
+
+        // Verify nonces are different
+        assert_ne!(nonce1, nonce2);
+
+        // Verify nonce format (first 8 bytes should be zero, last 4 contain counter)
+        assert_eq!(&nonce1[0..8], &[0u8; 8]);
+        assert_eq!(&nonce1[8..12], &1i32.to_be_bytes());
+
+        assert_eq!(&nonce_max[8..12], &i32::MAX.to_be_bytes());
+    }
+
+    #[test]
+    fn test_aead_tampered_ciphertext() {
+        let plaintext = b"Important message";
+        let key = [7u8; 32];
+        let nonce = nonce_from_counter(5);
+
+        let mut ciphertext = encrypt(plaintext, &key, &nonce).expect("Encryption failed");
+
+        // Tamper with ciphertext (flip a bit)
+        if let Some(byte) = ciphertext.get_mut(5) {
+            *byte ^= 0x01;
+        }
+
+        // Attempt decrypt - should fail due to authentication tag mismatch
+        let result = decrypt(&ciphertext, &key, &nonce);
+        assert!(result.is_err());
+    }
+}