can security ssf differ per interface

[Mivz <mivz@alpha.spugium.net>]

Hello,

I have the following security restrictions:

security ssf=0 update_ssf=112 simple_bind=56
require strong

And my heimdal uses my ldap as backend. I use a sasl-rexp to rewrite a ldapi interface connection by root to the rootdn. The rootdn is a valid kerberos ticket.
Now it can read, but not write updates, because of the update_ssf=112. 
How could I specify that the ldapi interace connection for root may update without high enc.?