[K12OSN] apt error..(sorry can't find in archives although I know it's been discussed)

[Huck]

Checking GPG signatures...
Unknown signature 
/var/cache/apt/archives/cvs_1.11.17-2.2.legacy_i386.rpm: (SHA1) DSA sha1 
md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/epiphany_1.2.10-0.2.3.legacy_i386.rpm: (SHA1) 
DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/mozilla_37%3a1.7.7-1.2.2.legacy_i386.rpm: (SHA1) 
DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/mozilla-nss_37%3a1.7.7-1.2.2.legacy_i386.rpm: 
(SHA1) DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/mozilla-nspr_37%3a1.7.7-1.2.2.legacy_i386.rpm: 
(SHA1) DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/openoffice.org-i18n_1.1.3-11.4.0.fc2_i386.rpm: 
(SHA1) DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/openoffice.org_1.1.3-11.4.0.fc2_i386.rpm: (SHA1) 
DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature 
/var/cache/apt/archives/openoffice.org-libs_1.1.3-11.4.0.fc2_i386.rpm: 
(SHA1) DSA sha1 md5 (GPG) NOT OK (MISSING KEYS: GPG#731002fa)
Unknown signature /var/cache/apt/archives/webmin_1.190-1_noarch.rpm: md5 
(GPG) NOT OK (MISSING KEYS: GPG#11f63c51)
E: Error(s) while checking package signatures:
0 unsigned package(s)
9 package(s) with unknown signatures
0 package(s) with illegal/corrupted signatures


how to get the right keys?