Decrypt AES256 encrypted bytes

Question

I\'ve never worked with encryption before. Actually I know nothing about encryption. I have a file encrypted with openssl tool using params:

openssl a

Answer 1

this may helps you

public void encrypt() throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
        // Here you read the cleartext.
        FileInputStream fis = new FileInputStream("data/cleartext");
        // This stream write the encrypted text. This stream will be wrapped by
        // another stream.
        FileOutputStream fos = new FileOutputStream("data/encrypted");

        // Length is 16 byte
        SecretKeySpec sks = new SecretKeySpec("yourkey".getBytes(), "AES");
        // Create cipher
        Cipher cipher = Cipher.getInstance("AES/CBC");
        cipher.init(Cipher.ENCRYPT_MODE, sks);
        // Wrap the output stream
        CipherOutputStream cos = new CipherOutputStream(fos, cipher);
        // Write bytes
        int b;
        byte[] d = new byte[8];
        while ((b = fis.read(d)) != -1) {
            cos.write(d, 0, b);
        }
        // Flush and close streams.
        cos.flush();
        cos.close();
        fis.close();
    }

Decrypt

public  void decrypt() throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
        FileInputStream fis = new FileInputStream("data/encrypted");

        FileOutputStream fos = new FileOutputStream("data/decrypted");
        SecretKeySpec sks = new SecretKeySpec("yourkey".getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC");
        cipher.init(Cipher.DECRYPT_MODE, sks);
        CipherInputStream cis = new CipherInputStream(fis, cipher);
        int b;
        byte[] d = new byte[8];
        while((b = cis.read(d)) != -1) {
            fos.write(d, 0, b);
        }
        fos.flush();
        fos.close();
        cis.close();
    }