feat: voice credits per poll

apps/subgraph/src/maci.ts

@@ -51,7 +51,7 @@ export function handleDeployPoll(event: DeployPollEvent): void {
 
 export function handleSignUp(event: SignUpEvent): void {
   const user = createOrLoadUser(event.params._userPubKeyX, event.params._userPubKeyY, event);
-  createOrLoadAccount(event.params._stateIndex, event, user.id, event.params._voiceCreditBalance);
+  createOrLoadAccount(event.params._stateIndex, event, user.id);
 
   const maci = createOrLoadMACI(event);
   maci.numSignUps = maci.numSignUps.plus(ONE_BIG_INT);

apps/subgraph/templates/subgraph.template.yaml

@@ -33,7 +33,7 @@ dataSources:
       eventHandlers:
         - event: DeployPoll(uint256,indexed uint256,indexed uint256,uint8)
           handler: handleDeployPoll
-        - event: SignUp(uint256,indexed uint256,indexed uint256,uint256,uint256,uint256)
+        - event: SignUp(uint256,uint256,indexed uint256,indexed uint256)
           handler: handleSignUp
       file: ./src/maci.ts
 templates:

packages/circuits/circom/anon/pollJoining.circom

@@ -1,42 +1,26 @@
 pragma circom 2.0.0;
 
-// circomlib import
-include "./mux1.circom";
-// zk-kit imports
-include "./safe-comparators.circom";
 // local imports
 include "../utils/hashers.circom";
 include "../utils/privToPubKey.circom";
 include "../trees/incrementalMerkleTree.circom";
 
 template PollJoining(stateTreeDepth) {
-    // Constants defining the structure and size of state.
-    var STATE_LEAF_LENGTH = 4;
+    // Constants defining the tree structure
     var STATE_TREE_ARITY = 2;
 
-    // Public key IDs.
-    var STATE_LEAF_PUB_X_IDX = 0;
-    var STATE_LEAF_PUB_Y_IDX = 1;
-    // Voice Credit balance id
-    var STATE_LEAF_VOICE_CREDIT_BALANCE_IDX = 2;
-    var N_BITS = 252;
-
     // User's private key
     signal input privKey;
     // Poll's private key
     signal input pollPrivKey;
     // Poll's public key
     signal input pollPubKey[2];
-    // The state leaf and related path elements.
-    signal input stateLeaf[STATE_LEAF_LENGTH];
     // Siblings
     signal input siblings[stateTreeDepth][STATE_TREE_ARITY - 1];
     // Indices
     signal input indices[stateTreeDepth];
     // User's hashed private key
     signal input nullifier;
-    // User's credits for poll joining (might be <= oldCredits)
-    signal input credits;
     // MACI State tree root which proves the user is signed up
     signal input stateRoot;
     // The actual tree depth (might be <= stateTreeDepth) Used in BinaryMerkleRoot
@@ -50,26 +34,21 @@ template PollJoining(stateTreeDepth) {
 
     // User private to public key
     var derivedPubKey[2] = PrivToPubKey()(privKey);
-    derivedPubKey[0] === stateLeaf[STATE_LEAF_PUB_X_IDX];
-    derivedPubKey[1] === stateLeaf[STATE_LEAF_PUB_Y_IDX];
-    
-    // Poll private to public key
+    // Hash the public key
+    var pubKeyHash = PoseidonHasher(2)([derivedPubKey[0], derivedPubKey[1]]);
+
+    // Poll private to public key to verify the correct one is used to join the poll (public input)
     var derivedPollPubKey[2] = PrivToPubKey()(pollPrivKey);
     derivedPollPubKey[0] === pollPubKey[0];
     derivedPollPubKey[1] === pollPubKey[1];
 
     // Inclusion proof  
-    var stateLeafHash = PoseidonHasher(4)(stateLeaf);
     var stateLeafQip = BinaryMerkleRoot(stateTreeDepth)(
-        stateLeafHash,
+        pubKeyHash,
         actualStateTreeDepth,
         indices,
         siblings
     );
 
     stateLeafQip === stateRoot;
-
-    // Check credits
-    var isCreditsValid = SafeLessEqThan(N_BITS)([credits, stateLeaf[STATE_LEAF_VOICE_CREDIT_BALANCE_IDX]]);
-    isCreditsValid === 1;
 }

packages/circuits/circom/circuits.json

@@ -3,7 +3,7 @@
     "file": "./anon/pollJoining",
     "template": "PollJoining",
     "params": [10],
-    "pubs": ["nullifier", "credits", "stateRoot", "pollPubKey", "pollId"]
+    "pubs": ["nullifier", "stateRoot", "pollPubKey", "pollId"]
   },
   "ProcessMessages_10-20-2_test": {
     "file": "./core/qv/processMessages",

packages/circuits/circom/trees/incrementalMerkleTree.circom

@@ -1,5 +1,7 @@
 pragma circom 2.0.0;
 
+// zk-kit imports
+include "./safe-comparators.circom";
 // circomlib import
 include "./mux1.circom";
 include "./comparators.circom";

packages/circuits/ts/__tests__/CeremonyParams.test.ts

@@ -78,7 +78,7 @@ describe("Ceremony param tests", () => {
       before(() => {
         // Sign up and publish
         const userKeypair = new Keypair(new PrivKey(BigInt(1)));
-        maciState.signUp(userKeypair.pubKey, voiceCreditBalance, BigInt(Math.floor(Date.now() / 1000)));
+        maciState.signUp(userKeypair.pubKey);
 
         pollId = maciState.deployPoll(
           BigInt(Math.floor(Date.now() / 1000) + duration),
@@ -90,7 +90,7 @@ describe("Ceremony param tests", () => {
         poll = maciState.polls.get(pollId)!;
 
         // update the state
-        poll.updatePoll(BigInt(maciState.stateLeaves.length));
+        poll.updatePoll(BigInt(maciState.pubKeys.length));
 
         // Join the poll
         const { privKey } = userKeypair;
@@ -221,7 +221,7 @@ describe("Ceremony param tests", () => {
         const commands: PCommand[] = [];
         // Sign up and publish
         const userKeypair = new Keypair();
-        maciState.signUp(userKeypair.pubKey, voiceCreditBalance, BigInt(Math.floor(Date.now() / 1000)));
+        maciState.signUp(userKeypair.pubKey);
 
         pollId = maciState.deployPoll(
           BigInt(Math.floor(Date.now() / 1000) + duration),
@@ -233,7 +233,7 @@ describe("Ceremony param tests", () => {
         poll = maciState.polls.get(pollId)!;
 
         // update the state
-        poll.updatePoll(BigInt(maciState.stateLeaves.length));
+        poll.updatePoll(BigInt(maciState.pubKeys.length));
 
         // Join the poll
         const { privKey } = userKeypair;

packages/circuits/ts/__tests__/PollJoining.test.ts

@@ -1,4 +1,3 @@
-import { expect } from "chai";
 import { type WitnessTester } from "circomkit";
 import { MaciState, Poll } from "maci-core";
 import { poseidon } from "maci-crypto";
@@ -23,7 +22,6 @@ describe("Poll Joining circuit", function test() {
     "siblings",
     "indices",
     "nullifier",
-    "credits",
     "stateRoot",
     "actualStateTreeDepth",
     "pollId",
@@ -53,7 +51,7 @@ describe("Poll Joining circuit", function test() {
       users = new Array(NUM_USERS).fill(0).map(() => new Keypair());
 
       users.forEach((userKeypair) => {
-        maciState.signUp(userKeypair.pubKey, voiceCreditBalance, BigInt(Math.floor(Date.now() / 1000)));
+        maciState.signUp(userKeypair.pubKey);
       });
 
       pollId = maciState.deployPoll(
@@ -64,7 +62,7 @@ describe("Poll Joining circuit", function test() {
       );
 
       poll = maciState.polls.get(pollId)!;
-      poll.updatePoll(BigInt(maciState.stateLeaves.length));
+      poll.updatePoll(BigInt(maciState.pubKeys.length));
 
       // Join the poll
       const { privKey } = users[0];
@@ -101,12 +99,10 @@ describe("Poll Joining circuit", function test() {
     it("should produce a proof", async () => {
       const privateKey = users[0].privKey;
       const stateLeafIndex = BigInt(1);
-      const credits = BigInt(10);
 
       const inputs = poll.joiningCircuitInputs({
         maciPrivKey: privateKey,
         stateLeafIndex,
-        credits,
         pollPrivKey,
         pollPubKey,
       }) as unknown as IPollJoiningInputs;
@@ -117,12 +113,10 @@ describe("Poll Joining circuit", function test() {
     it("should fail for fake witness", async () => {
       const privateKey = users[0].privKey;
       const stateLeafIndex = BigInt(1);
-      const credits = BigInt(10);
 
       const inputs = poll.joiningCircuitInputs({
         maciPrivKey: privateKey,
         stateLeafIndex,
-        credits,
         pollPrivKey,
         pollPubKey,
       }) as unknown as IPollJoiningInputs;
@@ -131,15 +125,5 @@ describe("Poll Joining circuit", function test() {
       const fakeWitness = Array(witness.length).fill(1n) as bigint[];
       await circuit.expectConstraintFail(fakeWitness);
     });
-
-    it("should fail for improper credits", () => {
-      const privateKey = users[0].privKey;
-      const stateLeafIndex = BigInt(1);
-      const credits = BigInt(105);
-
-      expect(() =>
-        poll.joiningCircuitInputs({ maciPrivKey: privateKey, stateLeafIndex, credits, pollPrivKey, pollPubKey }),
-      ).to.throw("Credits must be lower than signed up credits");
-    });
   });
 });