Details are described here: http://blogs.msdn.com/b/openspecification/archive/2009/09/12/msds-supportedencryptiontypes-episode-1-computer-accounts.aspx
Isn't that fixed in 4.2.0? There we have "net ads enctypes {list,set,delete}".
In the long run winbindd should use netr_LogonGetDomainInfo() at startup, when running as domain member.
closing, no feedback