CODEWITHSUNDEEP
javaexceptionencryption
Matthew J Coffman
Matthew J Coffman

Reputation: 322

Trouble with javax.crypto.Cipher

I have imported the following into my project

import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import java.io.*;

The following is telling me "Unhandled exception type NoSuchPaddingException"

Cipher c = Cipher.getInstance("AES");

I'm using JaveSE-1.6.

Any ideas what would be causing this?

Upvotes: 0

Views: 2333

Answers (1)

Chris Chambers
Chris Chambers

Reputation: 1365

Cipher.getInstance(...) throws two kinds of exceptions, and requires that you handle them.

Either have the method containing Cipher c = Cipher.getInstance("AES"); rethrow the exception if you wish to handle it elsewhere:

public void foo(){ throws Exception ... }

Or better yet, enclose the method in a try-catch block:

try{
   Cipher c = Cipher.getInstance("AES");
}
catch(Exception e){
   //do something about it
}

You can also get fancier and do this:

try{
   Cipher c = Cipher.getInstance("AES");
}
catch(NoSuchAlgorithmException e){
   //handle the case of having no matching algorithm
}
catch(NoSuchPaddingException e){
   //handle the case of a padding problem
}

Certain Java methods throw exceptions, and some of these require that you handle them. Anything in the Java API docs with Throws after the method requires handling. Generally there is a good reason they make you do this. In this case, if you can't get the correct cipher, you can't encrypt anything.

Upvotes: 5

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