feat: web frontend; middleware; serde (WIP?)

src/crypto.rs

@@ -63,9 +63,13 @@ pub fn encrypt(plaintext: &str, key: &str, iv: &str) -> Result<String, CryptoErr
     let encryptor = Aes128CbcEnc::new_from_slices(key_bytes, iv_bytes).map_err(CryptoError::Aes)?;
 
     // 2. Encrypt the plaintext with PKCS7 padding
-    let mut buffer = plaintext.as_bytes().to_vec();
+    // Allocate buffer with extra space for padding (AES block size is 16 bytes)
+    let plaintext_bytes = plaintext.as_bytes();
+    let mut buffer = vec![0u8; plaintext_bytes.len() + 16];
+    buffer[..plaintext_bytes.len()].copy_from_slice(plaintext_bytes);
+
     let ciphertext = encryptor
-        .encrypt_padded_mut::<Pkcs7>(&mut buffer, plaintext.len())
+        .encrypt_padded_mut::<Pkcs7>(&mut buffer, plaintext_bytes.len())
         .map_err(CryptoError::Pad)?;
 
     // 3. Base64 encode the ciphertext