Help in Java Encryption

[wtver87]

Hi everyone,

I've tried a lot of way but none of them works. What I'm trying to do is I'm trying to encrypt a string and store it to a file, then read that encryption and decrypt it so my program can use that string again. The storage is just using a FileOutputStream and I'm reading using FileInputStream, I can write it fine, but after I'm done reading the file and try to decrypt it, it give me javax.crypto.BadPaddingException

Here's a snippet of my code

FileInputStream fis = new FileInputStream(path 
	+"\\dat" + i + ".txt");
Scanner sc = new Scanner(fis);
String curr = "";
if (sc.hasNextLine())
	curr = sc.nextLine();
while(sc.hasNextLine())
{
        curr += '\n' + sc.nextLine();
}

System.out.println("Curr is: " + new String(curr));
data[i] = new String(gwc.decrypt(curr));
sc.close();

I've done the try catch too, i just ommited it for simplicity

Thank you in advance

[roots]

Why are you reading a "Encrypted Content" with scanner and adding \n on it ??

If possibe paste the gwc.decrypt

[wtver87]

Hi roots,

Thanks for the reply, I'm reading "The encrypted content" with scanner and adding '\n' on it is because sometimes the encryption result with something like this ~!@#$%%\n&^%$, which will be read by the scanner as the end of the input session, therefore what I did is when it's detected, add a '\n' to recover what Scanner has ignored + next token. Is there a better way of doing this? Is there a way I can say just take the whole thing till end of file?

	byte[] decrypt(String input)
	{
		System.out.println(input);
		return action(input, Cipher.DECRYPT_MODE);
	}

	private byte[] action(String input, int mode)
	{
		try {
			cipher.init(mode, key);
		} catch (InvalidKeyException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		catch(Exception e)
		{
			System.out.println("Unknown error in Cipher init");
		}
		byte [] enres = null;
		try {
			enres = cipher.doFinal(input.getBytes());
		} catch (IllegalBlockSizeException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (BadPaddingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch(Exception e)
		{
			System.out.println("Unknown error in crypting process");
		}
		return enres;
	}

[roots]

What you are doing is byte -> String -> byte[]
read as byte[] from inputstream and "update" that to Cipher. and at the end doFinal with empty byte to collect the output.
Respective javadoc should help you

Cipher (Java 2 Platform SE v1.4.2)[],%20int,%20int)
InputStream (Java 2 Platform SE v1.4.2)[],%20int,%20int)