Cipher - encrypt large String variable

Question

Hello,
I have a jUnit test for a simple Cipher encryption/decryption.
I want to write a test to encrypt large data.
Do I have to change the encryption variable type from String to a Stream class?
Anyone have suggestion?
package no.ssb.cipher;
import org.junit.*;
import static org.junit.Assert.*;
* Unit test for simple App.
public class SimpleStringCipherTest {
private SimpleStringCipher simpleStringCipher;
* Create the test case
* @param testName name of the test case
@Before
public void setUp()
simpleStringCipher = new SimpleStringCipher("tvnw63ufg9gh5392");
@Test
public void testBasicEncyption() throws Exception {         
String plainText = "2010 starts new decade.";
String encrypted = simpleStringCipher.encrypt(plainText);
System.out.println("Encrypted: " + encrypted);
assertTrue(!plainText.equals(encrypted));
String decrypted = simpleStringCipher.decrypt(encrypted);
assertEquals(plainText, decrypted);
@Test
public void testEncryptionIsNotURLSafe() throws Exception{
String plainText = "2010 starts new decade.";
String expectedValue = "abe6vPUFQ4xSMezuFF2HBNC3dW98iifMeM027PKKnNw=";
String encrypted = simpleStringCipher.encrypt(plainText);
assertTrue(!plainText.equals(encrypted));
assertTrue(expectedValue.equals(encrypted));
String decrypted = simpleStringCipher.decrypt(encrypted);
assertEquals(plainText, decrypted);
@Test(expected=IllegalArgumentException.class)
public void testInvalidSecretKey() throws Exception{
SimpleStringCipher invalidCipher = new SimpleStringCipher("tull");
@Test(expected=Exception.class)
public void testDecryptInvalidEncryptedString() throws Exception {
simpleStringCipher.decrypt("abe6vPUFQ4xSMezuFF2HBNC3dW98jjfMeM027PKKnNw");
}

Answer 1

Sorry, I am beginner and new in Cipher.
Hope my following question make more sense.
In production we have an error when decrypting
large data.
My existing unit test is shown and class I am testing
How can I write a new test, simulating the production error we have?
1.@Test
2.public void testBasicEncyption() throws Exception {
3.String plainText = "text to be encrypted."
4.String encrypted = simpleStringCipher.encrypt(plainText);
5.System.out.println("Encrypted: " + encrypted);
6.assertTrue(!plainText.equals(encrypted));
7.String decrypted = simpleStringCipher.decrypt(encrypted);
8.assertEquals(plainText, decrypted);
* Class to test *
package no.ssb.cipher;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base64;
public class SimpleStringCipher {
private static byte[] linebreak = {}; // Remove Base64 encoder default
// linebreak
private String secret; // secret key length must
// be 16
private SecretKey key;
private Cipher cipher;
private Base64 coder;
public SimpleStringCipher(String secretKey) {
if(secretKey.length()!=16){
throw new IllegalArgumentException("secretKey must be 16 digits");
this.secret = secretKey;
try {
key = new SecretKeySpec(secretKey.getBytes(), "AES");
cipher = Cipher.getInstance("AES/ECB/PKCS5Padding", "SunJCE");
coder = new Base64(32, linebreak, false);
} catch (Throwable t) {
t.printStackTrace();
public synchronized String encrypt(String plainText)
throws Exception {
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] cipherText = cipher.doFinal(plainText.getBytes());
return new String(coder.encode(cipherText));
public synchronized String decrypt(String codedText)
throws Exception {
byte[] encypted = coder.decode(codedText.getBytes());
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] decrypted = cipher.doFinal(encypted);
return new String(decrypted);
Edited by: 999969 on Apr 14, 2013 10:38 PM