python: investigate error directly

README.md

@@ -966,7 +966,7 @@ recovery data to this participant.
 #### participant\_investigate
 
 ```python
-def participant_investigate(blame_state: ParticipantBlameState, cinvestigation: CoordinatorInvestigationMsg) -> NoReturn
+def participant_investigate(error: UnknownFaultyParticipantOrCoordinatorError, cinvestigation: CoordinatorInvestigationMsg) -> NoReturn
 ```
 
 Perform a participant's blame step of a ChillDKG session. TODO

python/chilldkg_ref/chilldkg.py

@@ -424,10 +424,6 @@ class ParticipantState2(NamedTuple):
     dkg_output: DKGOutput
 
 
-class ParticipantBlameState(NamedTuple):
-    enc_blame_state: encpedpop.ParticipantBlameState
-
-
 def participant_step1(
     hostseckey: bytes, params: SessionParams, random: bytes
 ) -> Tuple[ParticipantState1, ParticipantMsg1]:
@@ -526,19 +522,12 @@ def participant_step2(
     params, idx, enc_state = state1
     enc_cmsg, enc_secshares = cmsg1
 
-    try:
-        enc_dkg_output, eq_input = encpedpop.participant_step2(
-            state=enc_state,
-            deckey=hostseckey,
-            cmsg=enc_cmsg,
-            enc_secshare=enc_secshares[idx],
-        )
-    except UnknownFaultyParticipantOrCoordinatorError as e:
-        # Convert from encpedpop.ParticipantBlameState into
-        # chilldkg.ParticipantBlameState.
-        assert isinstance(e.blame_state, encpedpop.ParticipantBlameState)
-        blame_state = ParticipantBlameState(e.blame_state)
-        raise UnknownFaultyParticipantOrCoordinatorError(blame_state, e.args) from e
+    enc_dkg_output, eq_input = encpedpop.participant_step2(
+        state=enc_state,
+        deckey=hostseckey,
+        cmsg=enc_cmsg,
+        enc_secshare=enc_secshares[idx],
+    )
 
     # Include the enc_shares in eq_input to ensure that participants agree on
     # all shares, which in turn ensures that they have the right recovery data.
@@ -601,12 +590,12 @@ def participant_finalize(
 
 
 def participant_investigate(
-    blame_state: ParticipantBlameState,
+    error: UnknownFaultyParticipantOrCoordinatorError,
     cinvestigation: CoordinatorInvestigationMsg,
 ) -> NoReturn:
     """Perform a participant's blame step of a ChillDKG session. TODO"""
     encpedpop.participant_investigate(
-        blame_state=blame_state.enc_blame_state,
+        error=error,
         cinvestigation=cinvestigation.enc_cinvestigation,
     )
 

python/chilldkg_ref/encpedpop.py

@@ -243,10 +243,10 @@ def participant_step2(
 
 
 def participant_investigate(
-    blame_state: ParticipantBlameState,
+    error: UnknownFaultyParticipantOrCoordinatorError,
     cinvestigation: CoordinatorInvestigationMsg,
 ) -> NoReturn:
-    simpl_blame_state, enc_secshare, pads = blame_state
+    simpl_blame_state, enc_secshare, pads = error.blame_state
     enc_partial_secshares, partial_pubshares = cinvestigation
     assert len(enc_partial_secshares) == len(pads)
     partial_secshares = [
@@ -257,7 +257,7 @@ def participant_investigate(
     simpl_cinvestigation = simplpedpop.CoordinatorInvestigationMsg(partial_pubshares)
     try:
         simplpedpop.participant_investigate(
-            simpl_blame_state, simpl_cinvestigation, partial_secshares
+            UnknownFaultyParticipantOrCoordinatorError(simpl_blame_state), simpl_cinvestigation, partial_secshares
         )
     except simplpedpop.SecshareSumError as e:
         # The secshare is not equal to the sum of the partial secshares in the

python/chilldkg_ref/simplpedpop.py

@@ -226,11 +226,11 @@ def participant_step2(
 
 
 def participant_investigate(
-    blame_state: ParticipantBlameState,
+    error: UnknownFaultyParticipantOrCoordinatorError,
     cinvestigation: CoordinatorInvestigationMsg,
     partial_secshares: List[Scalar],
 ) -> NoReturn:
-    n, idx, secshare, secshare_tweak, pubshare = blame_state
+    n, idx, secshare, secshare_tweak, pubshare = error.blame_state
     partial_pubshares = cinvestigation.partial_pubshares
 
     if GE.sum(*partial_pubshares) + secshare_tweak * G != pubshare:

python/example.py

@@ -101,7 +101,7 @@ async def participant(
         state2, eq_round1 = participant_step2(hostseckey, state1, cmsg1)
     except UnknownFaultyParticipantOrCoordinatorError as e:
         if blame_mode:
-            participant_investigate(e.blame_state, cblame)
+            participant_investigate(e, cblame)
         else:
             # If this participant does not support blame mode, it cannot
             # determine which party is faulty. Re-raise UnknownFaultyPartyError

python/tests.py

@@ -116,7 +116,7 @@ def simulate_simplpedpop(
             assert len(investigation_msgs) == len(pmsgs)
             try:
                 simplpedpop.participant_investigate(
-                    e.blame_state, investigation_msgs[i], partial_secshares
+                    e, investigation_msgs[i], partial_secshares
                 )
             # If we're not faulty, we should blame the faulty party.
             except FaultyParticipantOrCoordinatorError as e:
@@ -175,7 +175,7 @@ def simulate_encpedpop(
             investigation_msgs = encpedpop.coordinator_investigate(pmsgs)
             assert len(investigation_msgs) == len(pmsgs)
             try:
-                encpedpop.participant_investigate(e.blame_state, investigation_msgs[i])
+                encpedpop.participant_investigate(e, investigation_msgs[i])
             # If we're not faulty, we should blame the faulty party.
             except FaultyParticipantOrCoordinatorError as e:
                 assert i != faulty_idx[i]
@@ -224,7 +224,7 @@ def simulate_chilldkg(
             investigation_msgs = chilldkg.coordinator_investigate(pmsgs)
             assert len(investigation_msgs) == len(pmsgs)
             try:
-                chilldkg.participant_investigate(e.blame_state, investigation_msgs[i])
+                chilldkg.participant_investigate(e, investigation_msgs[i])
             # If we're not faulty, we should blame the faulty party.
             except FaultyParticipantOrCoordinatorError as e:
                 assert i != faulty_idx[i]