Can't get it to work!!! Please help with IllegalBlockSizeException

Question

I have tried several things, I have searched the forume many times ever
since yesterday, but I just can't figure this out. Here is my method to encrypt:
private void encryptPassword(String p)
try{
//generate key using DES algorithm
byte key[] = "ababcabc".getBytes();
SecretKeySpec secretKey = new SecretKeySpec(key,"DES");
//get cipher for DES algorithm
Cipher cipher = Cipher.getInstance ("DES");
cipher.init(Cipher.ENCRYPT_MODE,secretKey);
//encrypt password
//byte[] tmp = Base64.encode(p.getBytes());
byte[] encryptedPswd = cipher.doFinal(p.getBytes("UTF-8"));
//byte[] encryptedPswd = cipher.doFinal(tmp);
password = new String(encryptedPswd, "UTF-8");
catch(Exception e){
logger.error("ERROR: Unable to encrypt password "
                                   + "due to Exception: " + e);
And here is my method to decrypt:
private String decryptPassword()
try
{   //generate key using DES algorithm
byte key[] = "ababcabc".getBytes();
SecretKeySpec secretKey = new SecretKeySpec(key,"DES");
//get cipher for DES algorithm
Cipher cipher = Cipher.getInstance ("DES");
cipher.init(Cipher.DECRYPT_MODE,secretKey);
//byte[] cipherCode = Base64.decode(password.getBytes());
//byte[] decryptedPswd = cipher.doFinal(cipherCode);
byte[] decryptedPswd = cipher.doFinal(password.getBytes("UTF-8"));
return new String(decryptedPswd, "UTF-8");
catch(Exception e){
logger.error("ERROR: Unable to decrypt password "
                                   + "due to Exception: " + e);
return "";
As you can see, I have tried to use Base64 encoder, but that didn't work either. I got ArrayIndexOutOfBounds exception with that. I followed this thread to try that: http://forum.java.sun.com/thread.jsp?forum=9&thread=302490. I used to get BadPaddingException when I didn't use "UTF-8" encoding. But now I get IllegalBlockSizeException. Please let me know what I am doing wrong.
Thank you so much!
Malia

Answer 1

I found the answer to my question at this site: http://javaalmanac.com/egs/javax.crypto/DesString.html
The key is to use base64 encoding, but I didn't know that the class sun.misc.BASE64Encoder and sun.misc.BASE64Decoder comes with regular JDK. I searched for base64 encoders, but the implementation from Ostermiller didn't work for me. So, for those having the same problem, go to that site. Here is the snapshot:
public class DesEncrypter {
Cipher ecipher;
Cipher dcipher;
DesEncrypter(SecretKey key) {
try {
ecipher = Cipher.getInstance("DES");
dcipher = Cipher.getInstance("DES");
ecipher.init(Cipher.ENCRYPT_MODE, key);
dcipher.init(Cipher.DECRYPT_MODE, key);
} catch (javax.crypto.NoSuchPaddingException e) {
} catch (java.security.NoSuchAlgorithmException e) {
} catch (java.security.InvalidKeyException e) {
public String encrypt(String str) {
try {
// Encode the string into bytes using utf-8
byte[] utf8 = str.getBytes("UTF8");
// Encrypt
byte[] enc = ecipher.doFinal(utf8);
// Encode bytes to base64 to get a string
return new sun.misc.BASE64Encoder().encode(enc);
} catch (javax.crypto.BadPaddingException e) {
} catch (IllegalBlockSizeException e) {
} catch (UnsupportedEncodingException e) {
} catch (java.io.IOException e) {
return null;
public String decrypt(String str) {
try {
// Decode base64 to get bytes
byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);
// Decrypt
byte[] utf8 = dcipher.doFinal(dec);
// Decode using utf-8
return new String(utf8, "UTF8");
} catch (javax.crypto.BadPaddingException e) {
} catch (IllegalBlockSizeException e) {
} catch (UnsupportedEncodingException e) {
} catch (java.io.IOException e) {
return null;
Here's an example that uses the class:
try {
// Generate a temporary key. In practice, you would save this key.
// See also e464 Encrypting with DES Using a Pass Phrase.
SecretKey key = KeyGenerator.getInstance("DES").generateKey();
// Create encrypter/decrypter class
DesEncrypter encrypter = new DesEncrypter(key);
// Encrypt
String encrypted = encrypter.encrypt("Don't tell anybody!");
// Decrypt
String decrypted = encrypter.decrypt(encrypted);
} catch (Exception e) {