refactor(nonqv): optimize tally votes non qv circuit and contracts

reduce the number of constraints for the tally votes non qv circuit, and amend the repo code to support the changes. This includes a new Tally contract with reduced logic which has been removed from the circuit.
privacy-scaling-explorations · Feb 14, 2024 · ea632a9 · ea632a9
1 parent fa4313f
commit ea632a9
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diff --git a/circuits/circom/tallyVotesNonQv.circom b/circuits/circom/tallyVotesNonQv.circom
@@ -61,11 +61,7 @@ template TallyVotesNonQv(
     signal input currentSpentVoiceCreditSubtotal;
     signal input currentSpentVoiceCreditSubtotalSalt;
 
-    signal input currentPerVOSpentVoiceCredits[numVoteOptions];
-    signal input currentPerVOSpentVoiceCreditsRootSalt;
-
     signal input newResultsRootSalt;
-    signal input newPerVOSpentVoiceCreditsRootSalt;
     signal input newSpentVoiceCreditSubtotalSalt;
 
     //  ----------------------------------------------------------------------- 
@@ -163,18 +159,8 @@ template TallyVotesNonQv(
         }
     }
 
-    // Tally the spent voice credits per vote option
-    component newPerVOSpentVoiceCredits[numVoteOptions];
-    for (var i = 0; i < numVoteOptions; i++) {
-        newPerVOSpentVoiceCredits[i] = CalculateTotal(batchSize + 1);
-        newPerVOSpentVoiceCredits[i].nums[batchSize] <== currentPerVOSpentVoiceCredits[i] * iz.out;
-        for (var j = 0; j < batchSize; j++) {
-            newPerVOSpentVoiceCredits[i].nums[j] <== votes[j][i];
-        }
-    }
-
     // Verify the current and new tally
-    component rcv = ResultCommitmentVerifier(voteOptionTreeDepth);
+    component rcv = ResultCommitmentNonQvVerifier(voteOptionTreeDepth);
     rcv.isFirstBatch <== isFirstBatch.out;
     rcv.currentTallyCommitment <== currentTallyCommitment;
     rcv.newTallyCommitment <== newTallyCommitment;
@@ -184,13 +170,95 @@ template TallyVotesNonQv(
     rcv.currentSpentVoiceCreditSubtotalSalt <== currentSpentVoiceCreditSubtotalSalt;
     rcv.newSpentVoiceCreditSubtotal <== newSpentVoiceCreditSubtotal.sum;
     rcv.newSpentVoiceCreditSubtotalSalt <== newSpentVoiceCreditSubtotalSalt;
-    rcv.currentPerVOSpentVoiceCreditsRootSalt <== currentPerVOSpentVoiceCreditsRootSalt;
-    rcv.newPerVOSpentVoiceCreditsRootSalt <== newPerVOSpentVoiceCreditsRootSalt;
 
     for (var i = 0; i < numVoteOptions; i++) {
         rcv.currentResults[i] <== currentResults[i];
         rcv.newResults[i] <== resultCalc[i].sum;
-        rcv.currentPerVOSpentVoiceCredits[i] <== currentPerVOSpentVoiceCredits[i];
-        rcv.newPerVOSpentVoiceCredits[i] <== newPerVOSpentVoiceCredits[i].sum;
     }
 }
+
+// Verifies the commitment to the current results. Also computes and outputs a
+// commitment to the new results. Works for non quadratic voting 
+// - so no need for perVOSpentCredits as they would just match 
+// the results.
+template ResultCommitmentNonQvVerifier(voteOptionTreeDepth) {
+    var TREE_ARITY = 5;
+    var numVoteOptions = TREE_ARITY ** voteOptionTreeDepth;
+
+    // 1 if this is the first batch, and 0 otherwise
+    signal input isFirstBatch;
+    signal input currentTallyCommitment;
+    signal input newTallyCommitment;
+
+    // Results
+    signal input currentResults[numVoteOptions];
+    signal input currentResultsRootSalt;
+
+    signal input newResults[numVoteOptions];
+    signal input newResultsRootSalt;
+
+    // Spent voice credits
+    signal input currentSpentVoiceCreditSubtotal;
+    signal input currentSpentVoiceCreditSubtotalSalt;
+
+    signal input newSpentVoiceCreditSubtotal;
+    signal input newSpentVoiceCreditSubtotalSalt;
+
+    // Compute the commitment to the current results
+    component currentResultsRoot = QuinCheckRoot(voteOptionTreeDepth);
+    for (var i = 0; i < numVoteOptions; i++) {
+        currentResultsRoot.leaves[i] <== currentResults[i];
+    }
+
+    component currentResultsCommitment = HashLeftRight();
+    currentResultsCommitment.left <== currentResultsRoot.root;
+    currentResultsCommitment.right <== currentResultsRootSalt;
+
+    // Compute the commitment to the current spent voice credits
+    component currentSpentVoiceCreditsCommitment = HashLeftRight();
+    currentSpentVoiceCreditsCommitment.left <== currentSpentVoiceCreditSubtotal;
+    currentSpentVoiceCreditsCommitment.right <== currentSpentVoiceCreditSubtotalSalt;
+
+    // Commit to the current tally
+    component currentTallyCommitmentHasher = HashLeftRight();
+    currentTallyCommitmentHasher.left <== currentResultsCommitment.hash;
+    currentTallyCommitmentHasher.right <== currentSpentVoiceCreditsCommitment.hash;
+
+    // Check if the current tally commitment is correct only if this is not the first batch
+    component iz = IsZero();
+    iz.in <== isFirstBatch;
+    // iz.out is 1 if this is not the first batch
+    // iz.out is 0 if this is the first batch
+
+    // hz is 0 if this is the first batch
+    // currentTallyCommitment should be 0 if this is the first batch
+
+    // hz is 1 if this is not the first batch
+    // currentTallyCommitment should not be 0 if this is the first batch
+    signal hz;
+    hz <== iz.out * currentTallyCommitmentHasher.hash;
+
+    hz === currentTallyCommitment;
+
+    // Compute the root of the new results
+    component newResultsRoot = QuinCheckRoot(voteOptionTreeDepth);
+    for (var i = 0; i < numVoteOptions; i++) {
+        newResultsRoot.leaves[i] <== newResults[i];
+    }
+
+    component newResultsCommitment = HashLeftRight();
+    newResultsCommitment.left <== newResultsRoot.root;
+    newResultsCommitment.right <== newResultsRootSalt;
+
+    // Compute the commitment to the new spent voice credits value
+    component newSpentVoiceCreditsCommitment = HashLeftRight();
+    newSpentVoiceCreditsCommitment.left <== newSpentVoiceCreditSubtotal;
+    newSpentVoiceCreditsCommitment.right <== newSpentVoiceCreditSubtotalSalt;
+
+    // Commit to the new tally
+    component newTallyCommitmentHasher = HashLeftRight();
+    newTallyCommitmentHasher.left <== newResultsCommitment.hash;
+    newTallyCommitmentHasher.right <== newSpentVoiceCreditsCommitment.hash;
+
+    newTallyCommitmentHasher.hash === newTallyCommitment;
+}
diff --git a/circuits/ts/__tests__/TallyVotes.test.ts b/circuits/ts/__tests__/TallyVotes.test.ts
@@ -214,13 +214,14 @@ describe("TallyVotes circuit", function test() {
     });
 
     it("should produce the correct result commitments", async () => {
-      const generatedInputs = poll.tallyVotes() as unknown as ITallyVotesInputs;
-      const witness = await circuit.calculateWitness(generatedInputs);
-      await circuit.expectConstraintPass(witness);
+      const generatedInputs = poll.tallyVotesNonQv() as unknown as ITallyVotesInputs;
+
+      const witness = await circuitNonQv.calculateWitness(generatedInputs);
+      await circuitNonQv.expectConstraintPass(witness);
     });
 
     it("should produce the correct result if the inital tally is not zero", async () => {
-      const generatedInputs = poll.tallyVotes(false) as unknown as ITallyVotesInputs;
+      const generatedInputs = poll.tallyVotesNonQv() as unknown as ITallyVotesInputs;
 
       // Start the tally from non-zero value
       let randIdx = generateRandomIndex(Object.keys(generatedInputs).length);

diff --git a/cli/tests/e2e/e2e.nonQv.test.ts b/cli/tests/e2e/e2e.nonQv.test.ts
@@ -47,7 +47,7 @@ import { cleanVanilla, isArm } from "../utils";
  Test scenarios:
     1 signup, 1 message with quadratic voting disabled
  */
-describe("e2e tests", function test() {
+describe("e2e tests with non quadratic voting", function test() {
   const useWasm = isArm();
   this.timeout(900000);
 
@@ -69,6 +69,7 @@ describe("e2e tests", function test() {
     processWasm: testProcessMessagesNonQvWasmPath,
     tallyWasm: testTallyVotesNonQvWasmPath,
     useWasm,
+    useQuadraticVoting: false,
   };
 
   // before all tests we deploy the vk registry contract and set the verifying keys
@@ -90,7 +91,7 @@ describe("e2e tests", function test() {
 
     before(async () => {
       // deploy the smart contracts
-      maciAddresses = await deploy({ ...deployArgs, signer });
+      maciAddresses = await deploy({ ...deployArgs, signer, useQv: false });
       // deploy a poll contract
       await deployPoll({ ...deployPollArgs, signer });
     });

diff --git a/cli/tests/e2e/keyChange.test.ts b/cli/tests/e2e/keyChange.test.ts
@@ -147,7 +147,7 @@ describe("keyChange tests", function test() {
     it("should confirm the tally is correct", () => {
       const tallyData = JSON.parse(fs.readFileSync(testTallyFilePath).toString()) as TallyData;
       expect(tallyData.results.tally[0]).to.equal(expectedTally.toString());
-      expect(tallyData.perVOSpentVoiceCredits.tally[0]).to.equal(expectedPerVoteOptionTally.toString());
+      expect(tallyData.perVOSpentVoiceCredits?.tally[0]).to.equal(expectedPerVoteOptionTally.toString());
     });
   });
 
@@ -215,7 +215,7 @@ describe("keyChange tests", function test() {
     it("should confirm the tally is correct", () => {
       const tallyData = JSON.parse(fs.readFileSync(testTallyFilePath).toString()) as TallyData;
       expect(tallyData.results.tally[0]).to.equal(expectedTally.toString());
-      expect(tallyData.perVOSpentVoiceCredits.tally[0]).to.equal(expectedPerVoteOptionTally.toString());
+      expect(tallyData.perVOSpentVoiceCredits?.tally[0]).to.equal(expectedPerVoteOptionTally.toString());
     });
   });
 
@@ -283,7 +283,7 @@ describe("keyChange tests", function test() {
     it("should confirm the tally is correct", () => {
       const tallyData = JSON.parse(fs.readFileSync(testTallyFilePath).toString()) as TallyData;
       expect(tallyData.results.tally[2]).to.equal(expectedTally.toString());
-      expect(tallyData.perVOSpentVoiceCredits.tally[2]).to.equal(expectedPerVoteOptionTally.toString());
+      expect(tallyData.perVOSpentVoiceCredits?.tally[2]).to.equal(expectedPerVoteOptionTally.toString());
     });
   });
 });
diff --git a/cli/ts/commands/deploy.ts b/cli/ts/commands/deploy.ts
@@ -32,6 +32,7 @@ export const deploy = async ({
   poseidonT4Address,
   poseidonT5Address,
   poseidonT6Address,
+  useQv = true,
   signer,
   quiet = true,
 }: DeployArgs): Promise<DeployedContracts> => {
@@ -95,6 +96,7 @@ export const deploy = async ({
     signer,
     stateTreeDepth,
     quiet: true,
+    useQv,
   });
 
   const [maciContractAddress, stateAqContractAddress, pollFactoryContractAddress] = await Promise.all([

diff --git a/cli/ts/commands/genProofs.ts b/cli/ts/commands/genProofs.ts
@@ -412,7 +412,9 @@ export const genProofs = async ({
   // tally all ballots for this poll
   while (poll.hasUntalliedBallots()) {
     // tally votes in batches
-    tallyCircuitInputs = poll.tallyVotes(useQuadraticVoting) as unknown as CircuitInputs;
+    tallyCircuitInputs = useQuadraticVoting
+      ? (poll.tallyVotes() as unknown as CircuitInputs)
+      : (poll.tallyVotesNonQv() as unknown as CircuitInputs);
 
     try {
       // generate the proof
@@ -467,29 +469,19 @@ export const genProofs = async ({
     BigInt(asHex(tallyCircuitInputs!.newSpentVoiceCreditSubtotalSalt as BigNumberish)),
   );
 
-  // Compute newPerVOSpentVoiceCreditsCommitment
-  const newPerVOSpentVoiceCreditsCommitment = genTreeCommitment(
-    poll.perVOSpentVoiceCredits,
-    BigInt(asHex(tallyCircuitInputs!.newPerVOSpentVoiceCreditsRootSalt as BigNumberish)),
-    poll.treeDepths.voteOptionTreeDepth,
-  );
-
-  // Compute newTallyCommitment
-  const newTallyCommitment = hash3([
-    newResultsCommitment,
-    newSpentVoiceCreditsCommitment,
-    newPerVOSpentVoiceCreditsCommitment,
-  ]);
-
   // get the tally contract address
   const tallyContractAddress = tallyAddress || readContractAddress(`Tally-${pollId}`, network?.name);
 
+  let newPerVOSpentVoiceCreditsCommitment: bigint | undefined;
+  let newTallyCommitment: bigint;
+
   // create the tally file data to store for verification later
   const tallyFileData: TallyData = {
     maci: maciContractAddress,
     pollId: pollId.toString(),
     network: network?.name,
     chainId: network?.chainId.toString(),
+    isQuadratic: useQuadraticVoting,
     tallyAddress: tallyContractAddress,
     newTallyCommitment: asHex(tallyCircuitInputs!.newTallyCommitment as BigNumberish),
     results: {
@@ -502,12 +494,32 @@ export const genProofs = async ({
       salt: asHex(tallyCircuitInputs!.newSpentVoiceCreditSubtotalSalt as BigNumberish),
       commitment: asHex(newSpentVoiceCreditsCommitment),
     },
-    perVOSpentVoiceCredits: {
+  };
+
+  if (useQuadraticVoting) {
+    // Compute newPerVOSpentVoiceCreditsCommitment
+    newPerVOSpentVoiceCreditsCommitment = genTreeCommitment(
+      poll.perVOSpentVoiceCredits,
+      BigInt(asHex(tallyCircuitInputs!.newPerVOSpentVoiceCreditsRootSalt as BigNumberish)),
+      poll.treeDepths.voteOptionTreeDepth,
+    );
+
+    // Compute newTallyCommitment
+    newTallyCommitment = hash3([
+      newResultsCommitment,
+      newSpentVoiceCreditsCommitment,
+      newPerVOSpentVoiceCreditsCommitment,
+    ]);
+
+    // update perVOSpentVoiceCredits in the tally file data
+    tallyFileData.perVOSpentVoiceCredits = {
       tally: poll.perVOSpentVoiceCredits.map((x) => x.toString()),
       salt: asHex(tallyCircuitInputs!.newPerVOSpentVoiceCreditsRootSalt as BigNumberish),
       commitment: asHex(newPerVOSpentVoiceCreditsCommitment),
-    },
-  };
+    };
+  } else {
+    newTallyCommitment = hashLeftRight(newResultsCommitment, newSpentVoiceCreditsCommitment);
+  }
 
   fs.writeFileSync(tallyFile, JSON.stringify(tallyFileData, null, 4));