Test RSA

Check out [this StackOverflow answer](http://stackoverflow.com/questions/140131/convert-a-string-representation-of-a-hex-dump-to-a-byte-array-using-java/140861#140861) for a simpler (and possibly faster) implementation. I thought MIDP might also have an implementation, but it could only find the reverse (com.sun.midp.crypto.Util.hexEncode).