apt-get update GPG error

[piita]

I have GPG error during apt-get update and synaptic reload and cant acces synaptic - settings - repostories

cat /etc/apt/sources.list
#

# deb cdrom:[Debian GNU/Linux 7.0 _Kali_ - Official Snapshot amd64 LIVE/INSTALL Binary 20140526-16:38]/ kali contrib main non-free

#deb cdrom:[Debian GNU/Linux 7.0 _Kali_ - Official Snapshot amd64 LIVE/INSTALL Binary 20140526-16:38]/ kali contrib main non-free

## Security updates
deb cdrom:[Debian GNU/Linux 7.7.0 _Wheezy_ - Official amd64 DVD Binary-1 20141018-13:06]/ wheezy contrib main
deb http://security.kali.org/kali-security kali/updates main contrib non-free

error here

W: GPG error: http://security.kali.org kali/updates Release: The following signatures were invalid: KEYEXPIRED 1425567400 KEYEXPIRED 1425567400 KEYEXPIRED 1425567400