Migrating to Centos

Hi !

I've migrated most of my tao-1 boxes to centos-3. All went well... But I've 
got a server that won't do it.

Stangly, it seems to be caught in the middle of the migration, I don't know 
why.

I've got the yum and centos-yumconf from centos, so yum talks to the centos 
repository. When doing a yum upgrade, I get

Downloading Packages
warning: rpmts_HdrFromFdno: V3 DSA signature: NOKEY, key ID 025e513b
Error: Could not find the GPG Key necessary to validate pkg 
/var/cache/yum/update/packages/openssh-server-3.6.1p2-33.30.9.i386.rpm

I've tried to switch back to the tao repository with no luck.

Any hints ?

Nicolas