CryptoUtils

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

import com.deltafixes.exception.CryptoException;

public class CryptoUtils {
    public static void encrypt(String key, File inputFile, File outputFile)
            throws CryptoException {
        doCrypto(Cipher.ENCRYPT_MODE, key, inputFile, outputFile);
    }
    
    public static void decrypt(String key, File inputFile, File outputFile)
            throws CryptoException {
        doCrypto(Cipher.DECRYPT_MODE, key, inputFile, outputFile);
    }
    
    private static void doCrypto(int cipherMode, String key, File inputFile,
            File outputFile) throws CryptoException {
        try {
        		Key secretKey = new SecretKeySpec(keyDigest(key), "AES");
        		Cipher cipher = Cipher.getInstance("AES");
        		cipher.init(cipherMode, secretKey);

        		FileInputStream inputStream = new FileInputStream(inputFile);
        		byte[] inputBytes = new byte[(int) inputFile.length()];
        		inputStream.read(inputBytes);

        		byte[] outputBytes = cipher.doFinal(inputBytes);

        		FileOutputStream outputStream = new FileOutputStream(outputFile);
        		outputStream.write(outputBytes);

        		inputStream.close();
        		outputStream.close();
             
        } catch (NoSuchPaddingException | NoSuchAlgorithmException
                | InvalidKeyException | BadPaddingException
                | IllegalBlockSizeException | IOException ex) {
            throw new CryptoException("Error encrypting/decrypting file", ex);
        }
    }

	private static byte[] keyDigest(String key) throws CryptoException {
		byte[] keyDigest;
		MessageDigest sha = null;
		
		try {
			keyDigest = key.getBytes("UTF-8");
			sha = MessageDigest.getInstance("SHA-1");
	        keyDigest = sha.digest(keyDigest);
	        return Arrays.copyOf(keyDigest, 16);
		} catch (UnsupportedEncodingException | NoSuchAlgorithmException e) {
			throw new CryptoException("Error encrypting/decrypting file", e);
		}
	}
}