http://tth4he7kdfmfwq2k7yaj2ggjdva7rdpbch42q6xgoorbabjeklyfbmyd.onion/dark-fail-useful-verified-list-of-tor-hidden-services
If a hidden service adheres to the standard, it will supply dark.fail with their PGP public keys, a list of all official mirrors of a site signed with the owner’s PGP key and a PGP signed canary message with the latest Bitcoin block hash, and current date that must be updated every 14 days. This ensures the mirrors listed are both up-to-date and remain uncompromised.