Sounds like they had some type of encryption system running, perhaps encrypting their WAN traffic that relies on a central key server that went awol.
Something like a Group Encrypted Transport VPN
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/sec_conn_getvpn/configuration/xe-3s/sec-get-vpn-xe-3s-book/sec-get-vpn.html
Very secure but
Loose your key server / config or timings and things go bad quickly,
Loss or delay of replication leading to out of sync data leading to corruption leading to a mess.
Biting the hand that feeds IT
