Return the gpg signature info from a package:

import yum.packages
import rpmUtils.transaction
from rpmUtils.miscutils import getSigInfo
ts = rpmUtils.transaction.initReadOnlyTransaction()
lp = yum.packages.YumLocalPackage(ts, '/home/skvidal/yum-3.2.8-1.noarch.rpm')

print getSigInfo(lp.hdr)