import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

import de.flexiprovider.core.FlexiCoreProvider;

public class ExampleCrypt {

    public static void main(String[] args) throws Exception {

	Security.addProvider(new FlexiCoreProvider());

	Cipher cipher = Cipher.getInstance("AES/CFB/PKCS5Padding", "FlexiCore");
	KeyGenerator keyGen = KeyGenerator.getInstance("AES", "FlexiCore");
	SecretKey secKey = keyGen.generateKey();

	// Encrypt

	cipher.init(Cipher.ENCRYPT_MODE, secKey);

	String cleartextFile = "cleartext.txt";
	String ciphertextFile = "ciphertextSymm.txt";

	FileInputStream fis = new FileInputStream(cleartextFile);
	FileOutputStream fos = new FileOutputStream(ciphertextFile);
	CipherOutputStream cos = new CipherOutputStream(fos, cipher);

	byte[] block = new byte[8];
	int i;
	while ((i = fis.read(block)) != -1) {
	    cos.write(block, 0, i);
	}
	cos.close();

	// Decrypt

	String cleartextAgainFile = "cleartextAgainSymm.txt";

	cipher.init(Cipher.DECRYPT_MODE, secKey);

	fis = new FileInputStream(ciphertextFile);
	CipherInputStream cis = new CipherInputStream(fis, cipher);
	fos = new FileOutputStream(cleartextAgainFile);

	while ((i = cis.read(block)) != -1) {
	    fos.write(block, 0, i);
	}
	fos.close();
    }

}