TripleDES com chaves curtas

gistfile1.java

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
/**
 * http://tripoverit.blogspot.com/2009/06/tripledes-encryption-compatibility.html
 * http://nicholasbarger.com/2008/10/21/triple-des-encryption-class/
 * @author Waldinar Oliveira Neto
 *
 */
public class TripleDES {
	
	private String key;
	private String vector;

	public TripleDES(String key, String vector) {
		this.key = key(key);
		this.vector = vector(vector);

	}

	public String encryptText(String plainText) throws Exception {
		// ---- Use specified 3DES key and IV from other source --------------
		byte[] plaintext = plainText.getBytes();
		byte[] tdesKeyData = key.getBytes();

		// byte[] myIV = initializationVector.getBytes();

		Cipher c3des = Cipher.getInstance("DESede/CBC/PKCS5Padding");
		SecretKeySpec myKey = new SecretKeySpec(tdesKeyData, "DESede");
		IvParameterSpec ivspec = new IvParameterSpec(vector.getBytes());

		c3des.init(Cipher.ENCRYPT_MODE, myKey, ivspec);
		byte[] cipherText = c3des.doFinal(plaintext);

		return new sun.misc.BASE64Encoder().encode(cipherText);
	}

	public String decryptText(String cipherText) throws Exception {
		byte[] encData = new sun.misc.BASE64Decoder().decodeBuffer(cipherText);
		Cipher decipher = Cipher.getInstance("DESede/CBC/PKCS5Padding");
		byte[] tdesKeyData = key.getBytes();
		SecretKeySpec myKey = new SecretKeySpec(tdesKeyData, "DESede");
		IvParameterSpec ivspec = new IvParameterSpec(vector.getBytes());
		decipher.init(Cipher.DECRYPT_MODE, myKey, ivspec);
		byte[] plainText = decipher.doFinal(encData);
		return new String(plainText);
	}

	public static void main(String[] args) throws Exception {
		
		String key = "A2SGcb2%dfg00145";
		String vector = "@x1=001A2v2";
		
		TripleDES tripleDES = new TripleDES(key, vector);

		String encrypt = tripleDES.encryptText("NETO");
		System.out.println(encrypt);

		String decrypt = tripleDES.decryptText(encrypt);
		System.out.println(decrypt);
	}

	public static String key(String keyStr) {

		if (keyStr == null) {
			return null;
		}

		byte[] key = keyStr.getBytes();

		byte[] keyValue = new byte[24];

		if (key.length == 16) {
			// Create the third key from the first 8 bytes
			System.arraycopy(key, 0, keyValue, 0, 16);
			System.arraycopy(key, 0, keyValue, 16, 8);

		} else if (key.length != 24) {
			throw new IllegalArgumentException("A TripleDES key should be 24 bytes long");

		} else {
			keyValue = key;
		}

		return new String(keyValue);
	}

	public static String vector(String vectorStr) {

		if (vectorStr == null) {
			return null;
		}

		byte[] vector = vectorStr.getBytes();

		byte[] vectorValue = new byte[8];

		if (vector.length > 8) {
			System.arraycopy(vector, 0, vectorValue, 0, 8);

		} else if (vector.length != 8) {
			throw new IllegalArgumentException("A TripleDES vector should be 8 bytes long");

		} else {
			vectorValue = vector;
		}

		return new String(vectorValue);
	}

}