Mandating AES 256 in Java

Question

I'd like to write a Java method that mandates the use of AES-256. In order to do that I'd like to perform a check on the incoming SecretKey instance. In the case of RSA this is what I'm doing :-

public boolean checkKey(RSAKey key) {
    if ( key.getModulus().bitLength() == 1024 )
        return true;
    return false;
}

In the case of AES would the following do?

public boolean checkKey(SecretKey key) {
    if ( key.getAlgorithm() == "AES" && key.getEncoded().length == 256 )
        return true;
    return false;
}

But I get the feeling that this would be the wrong way to do it as I would be finding the length of the encoded key and not the key. How could I go about finding the length of my AES key?

Answer 1

For AES keys, the encoded form is just the raw bytes, so your check is fine in principle.

Just remember that the result will be a byte length, not a bit length, so check for == 32.