CryptoUtils.java

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Base64;

public class CryptoUtils {
    private String mAlgorithm;
    private String mTransformation;
    public CryptoUtils(String algorithm, String transformation){
        this.mAlgorithm=algorithm;
        this.mTransformation=transformation;
    }
    public String run(File inputFile, File outputFile, int cipherMode, String encodedKey) throws Exception{
        SecretKey secretKey = null;
        byte[] binary = null;
        if(cipherMode==Cipher.ENCRYPT_MODE) {
            KeyGenerator keyGen = KeyGenerator.getInstance("AES");
            keyGen.init(128);
            secretKey = keyGen.generateKey();
        }else if(cipherMode==Cipher.DECRYPT_MODE){
            byte[] decodedKey = Base64.getDecoder().decode(encodedKey);
            secretKey = new SecretKeySpec(decodedKey, 0, decodedKey.length, "AES");
        }
        Cipher cipher = Cipher.getInstance(mTransformation);
        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();
        return Base64.getEncoder().encodeToString(secretKey.getEncoded());
    }
    static String encrypt(File inputFile,File outputFile) throws Exception{
        int mode = Cipher.ENCRYPT_MODE;
        String key = new CryptoUtils("AES","AES").run(inputFile, outputFile, mode, null);
        return key;
    }

    static void decrypt(File inputFile,File outputFile, String key) throws Exception{
        int mode = Cipher.DECRYPT_MODE;
        new CryptoUtils("AES","AES").run(inputFile, outputFile, mode, key);
    }

    public String getmAlgorithm() {
        return mAlgorithm;
    }

    public void setmAlgorithm(String mAlgorithm) {
        this.mAlgorithm = mAlgorithm;
    }

    public String getmTransformation() {
        return mTransformation;
    }

    public void setmTransformation(String mTransformation) {
        this.mTransformation = mTransformation;
    }
}