Public key is not installed

I'm trying to install several packages on my Fedora core 5 machine.
Everything goes well for a while, but some end abruptly with a warning:
 
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID
66534c2b
and then "Public key for [package] is not installed."

And several display the same key ID - 66534c2b.  How can I find and
install the public key?
bruce

Install      2 Package(s)
Update       0 Package(s)
Remove       0 Package(s)
Total download size: 117 k
Is this ok [y/N]: y
Downloading Packages:
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID
66534c2b

Public key for ivtv-firmware-audio-0.0.1-5.at.noarch.rpm is not
installed
[bruce@blacky~]$                                                          


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