[Resolved] PasswordDigest

I am using a password digest to create a set of standard headers on a request:

        <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
                       xmlns:wssu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
            <wsse:UsernameToken>
                <wsse:Username>username</wsse:Username>
                <wsse:Password
                        Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordDigest">
                    weYI3nXd8LjMNVksCKFV8t3rgHh3Rw==
                </wsse:Password>
                <wsse:Nonce>WScqanjCEAC4mQoBE07sAQ==</wsse:Nonce>
                <wssu:Created>2013-04-16T01:24:32Z</wssu:Created>
            </wsse:UsernameToken>
        </wsse:Security>

Can someone please explain how the Nonce and Password fields are generated?

I ask because I have a class that picks these value and then uses them to validate the password field.

Currently known values are processed correctly, but when I run this in SoapUI my code fails.

Are both the password and Nonce fields just random base64 strings, or are they related in some way?