http://tzoz3bensgxyzs7da7lpgsn3a74h7hlbm4wa6ytq2tg6ktd57w22vqqd.onion/doc/about/openpgp_keys/signing_key_revocation/index.en.html
Distribution of the shares
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Each person from the Board, group A, has a *different* share, A1,
A2, ..., An.
On top of this, we defined three complementary groups, B, C, and D of
trusted people who have a close relationship with Tails but different
interests and different access to information about us.