macOS Java Crypto: AES not available?

wrldwzrd89 · Sep 25, 2011

Code:

public class ByteDumper {

import javax.crypto.SecretKeyFactory;

         public static void main(String[] args) {
		try {
			SecretKeyFactory skf = SecretKeyFactory.getInstance("AES");
			System.out.println(skf.toString());
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

This is the output it produces on my Mac OS X 10.7.1 system with the latest Java 6:

Code:

java.security.NoSuchAlgorithmException: AES SecretKeyFactory not available
	at javax.crypto.SecretKeyFactory.<init>(DashoA13*..)
	at javax.crypto.SecretKeyFactory.getInstance(DashoA13*..)
	at com.puttysoftware.bytedumper.ByteDumper.main(ByteDumper.java:6)

Huh. Strange. Why doesn't that work?

chown33 · Sep 25, 2011

It seems to be a pervasive problem. Google search terms: SecretKeyFactory aes exception

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7022467

I see the same result on all other Mac OS X versions.

lee1210 · Sep 25, 2011

Not sure if this will help, but the example seems to approach things differently:

http://java.sun.com/developer/technicalArticles/Security/AES/AES_v1.html

-Lee

wrldwzrd89 · Sep 25, 2011

lee1210 said:
Not sure if this will help, but the example seems to approach things differently:

http://java.sun.com/developer/technicalArticles/Security/AES/AES_v1.html

-Lee

Thanks, I was looking at that earlier... only problem is, the KeyGenerator approach won't work as I've already generated a suitable key to use for the encryption / decryption process.

chown33 · Sep 25, 2011

wrldwzrd89 said:
Thanks, I was looking at that earlier... only problem is, the KeyGenerator approach won't work as I've already generated a suitable key to use for the encryption / decryption process.

Exactly what is the problem you want to solve that needs a SecretKeyFactory?

wrldwzrd89 · Sep 25, 2011

chown33 said:
Exactly what is the problem you want to solve that needs a SecretKeyFactory?

As far as I can tell, the only way to get a SecretKey, which is in turn needed for a Cipher, from an array of bytes that is known to me, is to use SecretKeyFactory to create a SecretKeySpec, then use that to get the needed SecretKey. Is there something I am overlooking?

chown33 · Sep 25, 2011

The example Lee linked to shows this code:

Code:

       KeyGenerator kgen = KeyGenerator.getInstance("AES");
       kgen.init(128); // 192 and 256 bits may not be available

       // Generate the secret key specs.
       SecretKey skey = kgen.generateKey();
       byte[] raw = skey.getEncoded();

       SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");

       // Instantiate the cipher
       Cipher cipher = Cipher.getInstance("AES");

       cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

Note the absence of SecretKeyFactory.

I also googled: java aes cipher example

One of the top hits:
http://stackoverflow.com/questions/992019/java-256bit-aes-encryption

Again, note the absence of SecretKeyFactory (in the first post).

A later post uses SecretKeyFactory, but of type "PBKDF2WithHmacSHA1".

So it doesn't seem difficult to find examples that use AES ciphers, yet don't require an AES SecretKeyFactory.

In fact, given raw key bytes in byte[], the SecretKeySpec class seems to do what you want. Check the class reference docs, and look for examples.

wrldwzrd89 · Sep 25, 2011

chown33 said:
The example Lee linked to shows this code:

Code:

KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(128); // 192 and 256 bits may not be available // Generate the secret key specs. SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); // Instantiate the cipher Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

Note the absence of SecretKeyFactory.

I also googled: java aes cipher example

One of the top hits:
http://stackoverflow.com/questions/992019/java-256bit-aes-encryption

Again, note the absence of SecretKeyFactory (in the first post).

A later post uses SecretKeyFactory, but of type "PBKDF2WithHmacSHA1".

So it doesn't seem difficult to find examples that use AES ciphers, yet don't require an AES SecretKeyFactory.

In fact, given raw key bytes in byte[], the SecretKeySpec class seems to do what you want. Check the class reference docs, and look for examples.

Thanks. Figures it's something non-obvious.

chown33 · Sep 25, 2011

wrldwzrd89 said:
Thanks. Figures it's something non-obvious.

Java Crypto is like that. Get used to it.

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