How to save and restore a Key?

Question

Hi,
I Am working through some example code based on the Sun documentation here:
http://java.sun.com/j2se/1.4/docs/guide/security/jce/JCERefGuide.html
Here is part of the program:
        KeyGenerator keygen = KeyGenerator.getInstance("DES");
        SecretKey desKey = keygen.generateKey();
            Cipher desCipher;
        // Create the cipher
        desCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
        // Initialize the cipher for encryption
        desCipher.init(Cipher.ENCRYPT_MODE, desKey);
        // Our cleartext
        byte[] clearBytes =  "Joe".getBytes("UTF8");
        // Encrypt the cleartext
        byte[] cipherBytes = desCipher.doFinal(clearBytes);
        // Initialize the same cipher for decryption
        desCipher.init(Cipher.DECRYPT_MODE, desKey);
        // Decrypt the ciphertext
        byte[]  decryptedBytes = desCipher.doFinal(cipherBytes);This all works fine. Now, suppose I want to save desKey for future use. (Maybe I want to save my encrypted bytes to a file and decrypt them in the future. Maybe I want to give someone else the key for decrypting cipherBytes. )
In the Key interface there is a method getEncoded() => byte[] which appears to be a way to save the key as a byte array for future use. However, I don't see how to restore the key from the byte array. That is, I expected a Key interface constructor something like: Key(bytes[], encodedKey). What am I misunderstanding?
Regards,
Joe

Answer 1

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This works fine: SecretKey myKey = new SecretKeySpec(rawKey, "DES");
And indeed it does. Thanks, mut - I learned something new today. (Of course, I feel stupid for not having ever noticed that SKSpec isA SecretKey - but that happens to me allll the time...)
I couldn't get Grant's code to compile. Seems like
the SecretKeyFactory class doesn't have a
method named generateKey (in my 1.4 SDK).
I replaced generateKey with
generateSecret which compiled without error,Yup, sorry, I hadn't run the code thru a compiler or I'd've caught that.
but then when I ran the code the third line threw an
exception:
java.security.spec.InvalidKeySpecException:
Inappropriate key specification
Any idea what's going on?Interesting. I don't offhand see any way for one to work and the other to fail with the same raw data. Then again, having been wrong twice in one post, I'm feeling abruptly unqualified to comment! ;)
Will experiment some, and let you know what I find out.