Improve dummy compensation procedure (#205)

leio10 · web-flow · commit 8eb60ba64d75 · 2021-09-07T23:30:04.000+02:00
* fix: improve dummy compensation procedure

* test: fix broken tests

* style: fix lint issues
diff --git a/bulletin_board/server/app/services/voting_scheme/dummy/bulletin_board.rb b/bulletin_board/server/app/services/voting_scheme/dummy/bulletin_board.rb
@@ -35,10 +35,13 @@ def append_content(content)
 
       def process_create_election_message(_message_identifier, message, _content)
         raise RejectedMessage, "There must be at least 2 Trustees" if message.fetch(:trustees, []).count < 2
+
+        @state = { quorum: message[:scheme][:quorum] }
       end
 
       def process_start_key_ceremony_message(_message_identifier, _message, _content)
-        @state = { joint_election_key: 1, trustees: [] }
+        state[:joint_election_key] = 1
+        state[:trustees] = []
       end
 
       def process_key_ceremony_message(message_identifier, _message, content)
@@ -86,76 +89,81 @@ def process_start_tally_message(_message_identifier, _message, _content)
           end
         end
 
-        state[:compensations] = {}
-        state[:joint_compensations] = {}
-        state[:compensated] = 0
         state[:shares] = []
+        state[:missing] = []
+        state[:compensations] = []
         state[:joint_shares] = build_questions_struct(1)
+        state[:joint_compensations] = build_questions_struct(1)
 
         emit_response "tally.cast"
         append_content results
       end
 
       def process_tally_message(message_identifier, message, content)
         if message_identifier.subtype == "missing_trustee"
-          state[:compensations][message[:trustee_id]] = []
-          state[:joint_compensations][message[:trustee_id]] = build_questions_struct(1)
+          state[:missing] << message[:trustee_id] unless state[:shares].include?(message[:trustee_id])
 
           return
         end
 
         raise RejectedMessage, "The owner_id doesn't match the sender trustee" if content[:owner_id] != message_identifier.author_id
 
-        case message_identifier.subtype
-        when "share"
-          process_tally_share_message content
-        when "compensation"
-          process_compensation_message content
-        end
+        process_tally_message_by_subtype message_identifier.subtype, content
 
-        return unless state[:shares].count + state[:compensated] == election.trustees.count
+        return unless state[:missing].count + state[:shares].count == election.trustees.count &&
+                      state[:shares].count >= state[:quorum]
 
-        results = build_questions_struct(0)
-        state[:joint_shares].each do |question, answers|
-          answers.each do |answer, joint_share|
-            results[question][answer] = ((joint_share / state[:joint_election_key])**(1.0 / state[:trustees].count)).round
-          end
+        if state[:missing].any?
+          return unless state[:shares].count == state[:compensations].count
+
+          join_compensations
         end
 
-        emit_response "end_tally", results: results
+        emit_response "end_tally", results: join_shares
       end
 
-      def process_tally_share_message(content)
-        raise RejectedMessage, "The trustee already sent their share" if state[:shares].include?(content[:owner_id])
+      def process_tally_message_by_subtype(subtype, content)
+        case subtype
+        when "share"
+          raise RejectedMessage, "The trustee already sent their share" if state[:shares].include?(content[:owner_id])
 
-        state[:shares] << content[:owner_id]
+          state[:shares] << content[:owner_id]
+          state[:missing].delete(content[:owner_id])
 
-        content[:contests].each do |question, answers|
-          answers.each do |answer, share|
-            state[:joint_shares][question][answer] *= share
+          content[:contests].each do |question, answers|
+            answers.each do |answer, share|
+              state[:joint_shares][question][answer] *= share
+            end
+          end
+        when "compensation"
+          raise RejectedMessage, "The trustee already sent their compensation" if state[:compensations].include?(content[:owner_id])
+
+          state[:compensations] << content[:owner_id]
+
+          content[:contests].each do |question, answers|
+            answers.each do |answer, compensation|
+              state[:joint_compensations][question][answer] *= compensation
+            end
           end
         end
       end
 
-      def process_compensation_message(content)
-        compensation = state[:compensations][content[:trustee_id]]
-        raise RejectedMessage, "The trustee already sent their compensation for #{content[:trustee_id]}" if compensation.include?(content[:owner_id])
-
-        compensation << content[:owner_id]
-        content[:contests].each do |question, answers|
+      def join_compensations
+        state[:joint_compensations].each do |question, answers|
           answers.each do |answer, value|
-            state[:joint_compensations][content[:trustee_id]][question][answer] *= value
+            state[:joint_shares][question][answer] *=
+              (value**(1.0 / state[:compensations].count) * state[:joint_election_key]).round
           end
         end
+      end
 
-        return unless state[:compensations].count + state[:compensations][content[:trustee_id]].count == election.trustees.count
-
-        state[:joint_compensations][content[:trustee_id]].each do |question, answers|
-          answers.each do |answer, value|
-            state[:joint_shares][question][answer] *= (value.round**(1.0 / state[:shares].count)).round
+      def join_shares
+        results = build_questions_struct(0)
+        state[:joint_shares].each do |question, answers|
+          answers.each do |answer, joint_share|
+            results[question][answer] = ((joint_share / state[:joint_election_key])**(1.0 / state[:trustees].count)).round
           end
         end
-        state[:compensated] += 1
       end
 
       def build_questions_struct(initial_value)
diff --git a/bulletin_board/server/spec/factories/models.rb b/bulletin_board/server/spec/factories/models.rb
@@ -39,7 +39,7 @@
     authority { Authority.first }
     status { :created }
     unique_id { [authority.unique_id, election_id].join(".") }
-    voting_scheme_state { nil }
+    voting_scheme_state { Marshal.dump(quorum: 2) }
 
     after(:build) do |election, evaluator|
       election.trustees << evaluator.trustees_plus_keys.map(&:first)
@@ -57,12 +57,15 @@
       end
 
       status { :key_ceremony }
-      voting_scheme_state { Marshal.dump(joint_election_key: 1, trustees: trustees_done.map(&:slug)) }
+      voting_scheme_state { Marshal.dump(quorum: 2, joint_election_key: 1, trustees: trustees_done.map(&:slug)) }
     end
 
     trait :key_ceremony_ended do
       status { :key_ceremony_ended }
-      voting_scheme_state { Marshal.dump(joint_election_key: 1, trustees: trustees_plus_keys.map(&:first).map(&:slug)) }
+      voting_scheme_state do
+        Marshal.dump(quorum: 2, joint_election_key: Test::Elections.joint_election_key,
+                     trustees: trustees_plus_keys.map(&:first).map(&:slug))
+      end
     end
 
     trait :vote do
@@ -85,12 +88,12 @@
 
       after(:build) do |election, evaluator|
         joint_shares = Test::Elections.build_cast(election) { 1 }
-        election.voting_scheme_state = Marshal.dump(joint_election_key: Test::Elections.joint_election_key,
+        election.voting_scheme_state = Marshal.dump(quorum: 2,
+                                                    joint_election_key: Test::Elections.joint_election_key,
                                                     trustees: evaluator.trustees_plus_keys.map(&:first).map(&:slug),
                                                     joint_shares: joint_shares,
                                                     shares: evaluator.trustees_done.map(&:slug),
-                                                    compensations: {}, joint_compensations: {},
-                                                    compensated: 0)
+                                                    compensations: [], joint_compensations: {}, missing: [])
       end
     end
 
@@ -103,8 +106,7 @@
                                                     trustees: evaluator.trustees_plus_keys.map(&:first).map(&:slug),
                                                     joint_shares: joint_shares,
                                                     shares: evaluator.trustees_plus_keys.map(&:first).map(&:slug),
-                                                    compensations: {}, joint_compensations: {},
-                                                    compensated: 0)
+                                                    compensations: [], joint_compensations: {}, missing: [])
       end
     end
 
diff --git a/voting_schemes/dummy/js-adapter/src/trustee_wrapper.js b/voting_schemes/dummy/js-adapter/src/trustee_wrapper.js
@@ -1,8 +1,9 @@
-export const CREATED = 0;
-export const KEY_CEREMONY = 1;
-export const KEY_CEREMONY_ENDED = 2;
-export const TALLY = 3;
-export const TALLY_ENDED = 4;
+export const NONE = 0;
+export const CREATED = 1;
+export const KEY_CEREMONY = 2;
+export const KEY_CEREMONY_ENDED = 3;
+export const TALLY = 4;
+export const TALLY_ENDED = 5;
 
 export const CREATE_ELECTION = "create_election";
 export const START_KEY_CEREMONY = "start_key_ceremony";
@@ -29,10 +30,13 @@ export class TrusteeWrapper {
    */
   constructor({ trusteeId }) {
     this.trusteeId = trusteeId;
-    this.status = CREATED;
+    this.status = NONE;
     this.electionPublicKey = 0;
     this.jointElectionKey = 0;
     this.tallyCastMessage = null;
+    this.quorum = 0;
+    this.trusteesKeys = {};
+    this.trusteesShares = {};
   }
 
   /**
@@ -45,6 +49,13 @@ export class TrusteeWrapper {
    */
   processMessage(messageType, decodedData) {
     switch (this.status) {
+      case NONE: {
+        if (messageType === CREATE_ELECTION) {
+          this.quorum = decodedData.scheme.quorum;
+          this.status = CREATED;
+        }
+        break;
+      }
       case CREATED: {
         if (messageType === START_KEY_CEREMONY) {
           this.status = KEY_CEREMONY;
@@ -61,7 +72,10 @@ export class TrusteeWrapper {
         break;
       }
       case KEY_CEREMONY: {
-        if (messageType === END_KEY_CEREMONY) {
+        if (messageType === KEY_CEREMONY_STEP_1) {
+          const content = JSON.parse(decodedData.content);
+          this.trusteesKeys[content.owner_id] = content.election_public_key;
+        } else if (messageType === END_KEY_CEREMONY) {
           const content = JSON.parse(decodedData.content);
           this.jointElectionKey = content.joint_election_key;
           this.status = KEY_CEREMONY_ENDED;
@@ -92,30 +106,20 @@ export class TrusteeWrapper {
               contests,
             }),
           };
+        } else if (messageType === TALLY_SHARE) {
+          const content = JSON.parse(decodedData.content);
+          this.trusteesShares[content.owner_id] = true;
+
+          return this._compensate();
         } else if (messageType === TALLY_MISSING_TRUSTEE) {
-          const contests = JSON.parse(this.tallyCastMessage);
-          for (const [question, answers] of Object.entries(contests)) {
-            for (const [answer, value] of Object.entries(answers)) {
-              contests[question][answer] =
-                (1.0 *
-                  (value % this.electionPublicKey) *
-                  this.jointElectionKey) /
-                this.electionPublicKey /
-                this.electionPublicKey;
-            }
+          if (!(decodedData.truestee_id in this.trusteesShares)) {
+            this.trusteesShares[decodedData.truestee_id] = false;
+            return this._compensate();
           }
-
-          return {
-            messageType: TALLY_COMPENSATION,
-            content: JSON.stringify({
-              owner_id: this.trusteeId,
-              trustee_id: decodedData.trustee_id,
-              contests,
-            }),
-          };
         } else if (messageType === END_TALLY) {
           this.status = TALLY_ENDED;
         }
+
         break;
       }
     }
@@ -127,7 +131,7 @@ export class TrusteeWrapper {
    * @returns {boolean}
    */
   isFresh() {
-    return this.status === CREATED;
+    return this.status === NONE;
   }
 
   /**
@@ -187,4 +191,33 @@ export class TrusteeWrapper {
   isTallyDone() {
     return this.status >= TALLY_ENDED;
   }
+
+  _compensate() {
+    const trusteesCount = Object.keys(this.trusteesKeys).length;
+    const missingTrustees = Object.values(this.trusteesShares).filter(
+      (val) => !val
+    ).length;
+
+    if (
+      missingTrustees > 0 &&
+      Object.keys(this.trusteesShares).length === trusteesCount
+    ) {
+      const contests = JSON.parse(this.tallyCastMessage);
+      for (const [question, answers] of Object.entries(contests)) {
+        for (const [answer, value] of Object.entries(answers)) {
+          contests[question][answer] =
+            Math.pow(value % this.electionPublicKey, missingTrustees) /
+            Math.pow(this.electionPublicKey, trusteesCount - missingTrustees);
+        }
+      }
+
+      return {
+        messageType: TALLY_COMPENSATION,
+        content: JSON.stringify({
+          owner_id: this.trusteeId,
+          contests,
+        }),
+      };
+    }
+  }
 }
diff --git a/voting_schemes/dummy/js-adapter/src/trustee_wrapper.test.js b/voting_schemes/dummy/js-adapter/src/trustee_wrapper.test.js
