Java MD5 which one of these is correct?

Question

I am trying to Sip Register and I get the challenge from the server.

So I need to use the MD5 algorithm on the nonce and then send that to the server to authenticate.

I have come across two examples of MD5 encryption and I have tried both and each one gives a different string back to me, so I was wondering which one is the correct one to use?

Thanks in advance

EDIT:

Ok thanks for the commons codecs.

I have edited it because I have to encode the nonce value I get back from the server with my username and password to send it back.

So it is a particuler type of encoding for SIP registration, can anyone point to a tutorial on how to do this? Or have any hints?

Answer 1

One obvious problem with the first one is that you produce the hex string the wrong way. When any value in messageDigest is less than 16, then you'll produce a single-digit hex string (for example A) instead of a two-digit one (0A).

Answer 2

Both are incorrect. Your conversion from the byte array to a hexadecimal string is broken. I highly recommend using http://commons.apache.org/codec/ from the ASF which can do this for you:

Hex.encodeHexString(yourByteArray);

But if you're using commons-codec, you can also do this:

String sessionid = "1ddfdf99abfe5690dc1243875";
String md5HexString = DigestUtils.md5Hex(sessionid);

and you're done. Neat, isn't it? :-)