nsupdate a key file

[Andreas Moroder]

Hello,

our bind8 is configured to accept eexternal updates ( from dhcp ) olny 
with a secret shared key

In the named.conf there are the following lines

key DHCP_UPDATER {
   algorithm HMAC-MD5.SIG-ALG.REG.INT;
   secret mysecretkeywashere==;
};

zone "sb-brixen.it" in {
         type master;
         file "sb-brixen.zone";
         allow-update { key DHCP_UPDATER; };
};

Now I would like to update via nsupdate.
nsupdate nees a key file, but I have cancelled the original file.

Is it possible to rebuild the key-file from the secret in named.conf or 
does this contain a completely different key ?

Thanks
Andreas