Minor correction, this is the official onion for security.debian.org (https://onion.debian.org):
deb http://sgvtcaew4bxjd7ln.onion/debian-security jessie/updates main This one is an unofficial security.debian.org mirror run by me: deb http://dju2peblv7upfz3q.onion/debian-security jessie/updates main
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