Tarefa 2.1 - Experimentar criptografia simétrica com AES


package encrypter;

public class Main {
 
    /**
     * @param args
     */
    
    public static void main(String[] args) {
 
        String informacao = "Lynyrd Skynyrd";
        String informacaoCriptografada = null;
        String informacaoDescriptografada = null;

        try {
            informacaoCriptografada = Encrypter.encriptar(Encrypter.CHAVE, informacao);
            System.out.println("Informação criptografada: " + informacaoCriptografada);
 
            informacaoDescriptografada = Encrypter.decriptar(Encrypter.CHAVE, informacaoCriptografada);
            System.out.println("Informação descriptografada: " + informacaoDescriptografada);
        } catch (EncryptorException e) {
            e.printStackTrace();
        }
    }
    
}


package encrypter;

public class EncryptorException extends Exception {
 
    private static final long serialVersionUID = -1295447857016462572L;
 
    public EncryptorException(String mensagem) {
        super(mensagem);
    }
}


package encrypter;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

import javax.crypto.KeyGenerator;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
  
public class Encrypter {

private static final String METODO_ENCRIPTACAO = "AES";

public static final byte[] CHAVE = {85, 10, 0, -25, 68, 88, 46, 37, 107, 48, 10, -1, -37, -90, 70, -36};;

public static String encriptar(byte[] key, String value)
			throws EncryptorException {

		try {
			SecretKeySpec skeySpec = new SecretKeySpec(key, METODO_ENCRIPTACAO);

			Cipher cipher = Cipher.getInstance(METODO_ENCRIPTACAO);
			cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
			byte[] encrypted = cipher.doFinal(value.getBytes());

			return new BASE64Encoder().encode(encrypted);
		}
		catch (Exception e) {
			throw new EncryptorException("Erro ao criptografar informações " + e.getMessage());
		}
	}

public static String decriptar(byte[] key, String encrypted)
			throws EncryptorException {

		byte[] decrypted = null;

		try {
			SecretKeySpec skeySpec = new SecretKeySpec(key, METODO_ENCRIPTACAO);

			byte[] decoded = new BASE64Decoder().decodeBuffer(encrypted);

			Cipher cipher = Cipher.getInstance(METODO_ENCRIPTACAO);
			cipher.init(Cipher.DECRYPT_MODE, skeySpec);
			decrypted = cipher.doFinal(decoded);
		}
		catch (Exception e) {
			throw new EncryptorException("Erro ao descriptografar informações " + e.getMessage());
		}

		return new String(decrypted);
	}
}