[Yum] warning: rpmts_HdrFromFdno: V3 DSA signature: NOKEY, key ID 66534c2b

[Cormac J. Gebruers]

Yum has been running happily for an age on FC2 (kernel 2.6.9-1.6_FC2). 
Last week I did my usual "yum update" and it failed (output below). I've 
done a "yum clean all" but still can't do an update today.

Suggestions please?

Regards
Cormac

Yum error output:

warning: rpmts_HdrFromFdno: V3 DSA signature: NOKEY, key ID 66534c2b
public key not available for 
//var/cache/yum/at-stable/packages/popt-1.9.1-21_35.rhfc2.at.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/opensp-1.5.1-9.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/libosp4-1.5.1-9.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/lm_sensors-2.8.8-36.rhfc2.at.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/rpm-devel-4.3.2-21_35.rhfc2.at.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/librpm4.3-4.3.2-21_35.rhfc2.at.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/lftp-3.0.12-19.rhfc2.at.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/rpm-4.3.2-21_35.rhfc2.at.i386.rpm
public key not available for 
//var/cache/yum/at-stable/packages/rpm-python-4.3.2-21_35.rhfc2.at.i386.rpm