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When leader elections are disabled, ignore messages for unselected VSSes
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If the leader has not picked a VSS, and we've seen evidence of their
choice of the T+1 VSSes to be used to create the key, we can ignore
messages for the unselected VSSes and save on doing a lot of work.
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@Vagabond
Vagabond committed Mar 12, 2021
1 parent 303ccb8 commit 687cff7
Showing 1 changed file with 78 additions and 55 deletions.
133 changes: 78 additions & 55 deletions src/dkg_hybriddkg.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -117,65 +117,75 @@ start(DKG = #dkg{id=Id, u=G1}) ->
{send, dkg_util:wrap({vss, Id}, ToSend)}}.

handle_msg(DKG=#dkg{await_vss = true}, Sender, {{vss, SharesId}, SharesMsg}) ->
case dkg_hybridvss:handle_msg(maps:get(SharesId, DKG#dkg.shares_map), Sender, SharesMsg) of
{_Shares, ignore} ->
{DKG, ignore};
{NewShares, ok} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)}, ok};
{NewShares, {send, ToSend}} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)},
{send, dkg_util:wrap({vss, SharesId}, ToSend)}};
{NewShares, {result, {_Session, Commitment, Si}}} ->
NewDKG = DKG#dkg{shares_map = maps:put(SharesId, NewShares, DKG#dkg.shares_map),
shares_results = maps:put(SharesId, {Commitment, Si}, DKG#dkg.shares_results),
shares_seen = [SharesId | DKG#dkg.shares_seen]
},
case output_ready(NewDKG, NewDKG#dkg.shares_acked) of
true ->
{Shard, VerificationKey, PublicKeyShares} = output(NewDKG, NewDKG#dkg.shares_acked),
{NewDKG, {result, {Shard, VerificationKey, PublicKeyShares}}};
false ->
{NewDKG, ok}
end
case is_chosen_vss(SharesId, DKG) of
true ->
case dkg_hybridvss:handle_msg(maps:get(SharesId, DKG#dkg.shares_map), Sender, SharesMsg) of
{_Shares, ignore} ->
{DKG, ignore};
{NewShares, ok} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)}, ok};
{NewShares, {send, ToSend}} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)},
{send, dkg_util:wrap({vss, SharesId}, ToSend)}};
{NewShares, {result, {_Session, Commitment, Si}}} ->
NewDKG = DKG#dkg{shares_map = maps:put(SharesId, NewShares, DKG#dkg.shares_map),
shares_results = maps:put(SharesId, {Commitment, Si}, DKG#dkg.shares_results),
shares_seen = [SharesId | DKG#dkg.shares_seen]
},
case output_ready(NewDKG, NewDKG#dkg.shares_acked) of
true ->
{Shard, VerificationKey, PublicKeyShares} = output(NewDKG, NewDKG#dkg.shares_acked),
{NewDKG, {result, {Shard, VerificationKey, PublicKeyShares}}};
false ->
{NewDKG, ok}
end
end;
false ->
{DKG, ignore}
end;
handle_msg(DKG=#dkg{leader = Leader}, Sender, {{vss, SharesId}, SharesMsg}) ->
case dkg_hybridvss:handle_msg(maps:get(SharesId, DKG#dkg.shares_map), Sender, SharesMsg) of
{_Shares, ignore} ->
{DKG, ignore};
{NewShares, ok} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)}, ok};
{NewShares, {send, ToSend}} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)}, {send, dkg_util:wrap({vss, SharesId}, ToSend)}};
{NewShares, {result, {_Session, Commitment, Si}}} ->
%% upon (Pd, τ, out, shared, Cd , si,d , Rd ) (first time):
%% Qhat ← {Pd}; Rhat ← {Rd}
%% if |Qhat| = t + 1 and Qbar = ∅ then
%% if Pi = L then
%% send the message (L, τ, send, Qhat, Rhat) to each Pj
%% else
%% delay ← delay(T); start timer(delay)

NewDKG = DKG#dkg{shares_map = maps:put(SharesId, NewShares, DKG#dkg.shares_map),
shares_results = maps:put(SharesId, {Commitment, Si}, DKG#dkg.shares_results),
shares_seen = [SharesId | DKG#dkg.shares_seen]
},
case length(NewDKG#dkg.shares_seen) == NewDKG#dkg.t + 1 andalso length(NewDKG#dkg.shares_acked) == 0 of
true ->
case NewDKG#dkg.id == Leader of
case is_chosen_vss(SharesId, DKG) of
true ->
case dkg_hybridvss:handle_msg(maps:get(SharesId, DKG#dkg.shares_map), Sender, SharesMsg) of
{_Shares, ignore} ->
{DKG, ignore};
{NewShares, ok} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)}, ok};
{NewShares, {send, ToSend}} ->
{DKG#dkg{shares_map=maps:put(SharesId, NewShares, DKG#dkg.shares_map)}, {send, dkg_util:wrap({vss, SharesId}, ToSend)}};
{NewShares, {result, {_Session, Commitment, Si}}} ->
%% upon (Pd, τ, out, shared, Cd , si,d , Rd ) (first time):
%% Qhat ← {Pd}; Rhat ← {Rd}
%% if |Qhat| = t + 1 and Qbar = ∅ then
%% if Pi = L then
%% send the message (L, τ, send, Qhat, Rhat) to each Pj
%% else
%% delay ← delay(T); start timer(delay)

NewDKG = DKG#dkg{shares_map = maps:put(SharesId, NewShares, DKG#dkg.shares_map),
shares_results = maps:put(SharesId, {Commitment, Si}, DKG#dkg.shares_results),
shares_seen = [SharesId | DKG#dkg.shares_seen]
},
case length(NewDKG#dkg.shares_seen) == NewDKG#dkg.t + 1 andalso length(NewDKG#dkg.shares_acked) == 0 of
true ->
{NewDKG, {send, [{multicast, {send, {vss_ready_proofs,
[ {SId, dkg_commitment:ready_proofs(C)} || {SId, {C, _}} <- maps:to_list(NewDKG#dkg.shares_results)]
}
}
}
]
}};
case NewDKG#dkg.id == Leader of
true ->
{NewDKG, {send, [{multicast, {send, {vss_ready_proofs,
[ {SId, dkg_commitment:ready_proofs(C)} || {SId, {C, _}} <- maps:to_list(NewDKG#dkg.shares_results)]
}
}
}
]
}};
false ->
{NewDKG, start_timer}
end;
false ->
{NewDKG, start_timer}
end;
false ->
{NewDKG, ok}
end
{NewDKG, ok}
end
end;
false ->
{DKG, ignore}
end;

%% upon a message (L, τ, send, Q, R/M) from L (first time):
Expand Down Expand Up @@ -646,6 +656,19 @@ result_name(Key) when is_atom(Key) ->
"result_" ++ Int = L,
list_to_integer(Int).

is_chosen_vss(_, #dkg{elections_allowed=true}) ->
%% never optimize these VSSes away if we do elections
true;
is_chosen_vss(VSSID, DKG) ->
case maps:size(DKG#dkg.echo_counts) + maps:size(DKG#dkg.ready_counts) of
0 ->
%% no echoes/readies yet, so assume we need it
true;
_ ->
%% check if any echo or ready mentions this VSS ID
lists:any(fun({_Leader, SelectedShares}) -> lists:member(VSSID, SelectedShares) end, maps:keys(DKG#dkg.echo_counts) ++ maps:keys(DKG#dkg.ready_counts))
end.

-spec status(dkg()) -> map().
status(DKG) ->
#{id => DKG#dkg.id,
Expand Down

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