javax.crypto.BadPaddingException: Given final block not properly padded

[Kevin P Smith]

Hi

Wondering if anyone can help me with what appears to be an intermintent problem with decrypting database data...

I am using teh below (snippets) code to encrypt users' private data to store in a database, then decrypt so they can view it.


To encrypt:

Cipher cipher = Cipher.getInstance("DESede");
byte[] bytes = cipher.doFinal(value.getBytes());
String encrypted = new String(bytes);[code]

This String is then stored in a database under a varchar column(s)

To decrypt: 
[code]Cipher cipher = Cipher.getInstance("DESede");
byte[] bytes = cipher.doFinal(value.getBytes());
String decrypted = new String(bytes);[code]

Now seemingly randomly I get the occasional 

[code]javax.crypto.BadPaddingException: Given final block not properly padded

I have read around the forums and most people seem to say it's because when converting the bytes to a String the encrypted data becomes compromised, but I can
not see any other way in which I can handle this encrypted data and pass it to the database then back again.

Any suggestions?

[Ulf Dittmer]

You shouldn't use "new String(...)" and "String.getBytes()" to perform the conversion - that implies the data is character data, which simply isn't the case. The easiest would probably be to use base-64 to convert a byte[] into a string; the Apache Commons Codec library can do that.

[Kevin P Smith]

Cheers for that, the following code seems to be working, although I haven't fully tested it (don't know if I dare incase I get another 'random' exception!)

	private static String encrypter(String value) {
		try {
			SecretKey key =SecretKeyManagerAbst.getSecretkey();
			Cipher cipher = Cipher.getInstance(StaticValues.SECRET_KEY_TYPE);
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] plainTxtBytes = value.getBytes(StaticValues.UTF_8);
			byte[] encBytes = cipher.doFinal(plainTxtBytes);
			return new sun.misc.BASE64Encoder().encode(encBytes);
		} catch (Exception ex) {
			return value;
		}
	}
	
	public static String decrypter(String value) {
		try {
			SecretKey key = SecretKeyManagerAbst.getSecretkey();
			Cipher cipher = Cipher.getInstance(StaticValues.SECRET_KEY_TYPE);
			cipher.init(Cipher.DECRYPT_MODE, key);
			byte[] encBytes = new sun.misc.BASE64Decoder().decodeBuffer(value);
			byte[] plainTxtBytes = cipher.doFinal(encBytes);
			return new String(plainTxtBytes);
		} catch (Exception ex) {
			return value;
		}
	}

[Shital Joshi]

Ulf Dittmer wrote:You shouldn't use "new String(...)" and "String.getBytes()" to perform the conversion - that implies the data is character data, which simply isn't the case. The easiest would probably be to use base-64 to convert a byte[] into a string; the Apache Commons Codec library can do that.

i tried the same, but the conversion i am not being able to perform, it gives me error that " Access restriction: BASE64Decoder() " , what to do?
i have all jar files even rt.jar and jce.jar also

please help me out, i facing problem in decryption