Integrate with solidity implementation

contracts/Ballot.sol

@@ -2,6 +2,8 @@
 
 pragma solidity >=0.7.0 <0.9.0;
 
+import "hardhat/console.sol";
+
 contract Ballot {
     struct Voter {
         bool hasRightToVote;
@@ -24,6 +26,7 @@ contract Ballot {
     uint256 public yesCount;
     uint256 public voteCount;
     address public verifierContractAddress;
+    uint256 public merkleRoot;
 
     constructor(address _verifierContractAddress) {
         chairperson = msg.sender;
@@ -52,15 +55,27 @@ contract Ballot {
         commitList.push(commit);
     }
 
+    function setMerkleRoot(uint256 newMerkleRoot) public {
+        require(
+            msg.sender == chairperson,
+            "Only chairperson can set the merkle root!"
+        );
+        merkleRoot = newMerkleRoot;
+    }
+
     function revealVote(
         bool _vote,
         bytes32 serialNumber,
-        bytes32[10] memory commitsForProof,
         Verifier.Proof memory proof
     ) public {
+        require(
+            merkleRoot != 0,
+            "Merkle root has not been set by the chairperson!"
+        );
+
         // validate proof
         // call sokrates
-        uint256[85] memory proof_inputs;
+        uint256[13] memory proof_inputs;
         uint256 j = 0;
         if (_vote) {
             proof_inputs[j] = 1;
@@ -77,28 +92,22 @@ contract Ballot {
                 break;
             }
         }
-        for (uint256 c_index = 0; c_index < 10; c_index++) {
-            bytes32 commit = commitsForProof[c_index];
-            for (uint256 i = 7; i >= 0; i--) {
-                proof_inputs[j] = uint256(commit >> (i * 32)) & 0xffffffff;
-                j += 1;
-                if (i == 0) {
-                    break;
-                }
+        for (uint256 i = 7; i >= 0; --i) {
+            proof_inputs[j] = uint256(merkleRoot >> (i * 32)) & 0xffffffff;
+            j += 1;
+            if (i == 0) {
+                break;
             }
         }
 
-        Verifier v = Verifier(verifierContractAddress);
-        require(v.verifyTx(proof, proof_inputs));
-
-        // is commitsForProof subset of commits
-        for (uint256 i = 0; i < commitsForProof.length; ++i) {
-            bytes32 commitInProof = commitsForProof[i];
-            if (commitInProof != 0) {
-                require(commits[commitInProof]);
-            }
+        console.log("Inputs:");
+        for (uint256 i = 0; i < 13; i++) {
+            console.log(proof_inputs[i]);
         }
 
+        Verifier v = Verifier(verifierContractAddress);
+        require(v.verifyTx(proof, proof_inputs), "Proof does not verify!");
+
         require(!seenSerialNumbers[serialNumber], "Already revealed!");
         seenSerialNumbers[serialNumber] = true;
 
@@ -126,12 +135,7 @@ interface Verifier {
         G1Point c;
     }
 
-    function verifyTx(Proof memory proof, uint256[85] memory input)
-        external
-        view
-        returns (bool r);
-
-    function testVerifyTx(Proof memory proof, uint256[85] memory input)
+    function verifyTx(Proof memory proof, uint256[13] memory input)
         external
         view
         returns (bool r);

src/provers.py

@@ -1,13 +1,12 @@
-from abc import ABC, abstractmethod
 import hashlib
-import shutil
-import os
-from pathlib import Path
 import json
 import math
-from typing import List, Tuple
+import os
+import shutil
+from abc import ABC, abstractmethod
+from pathlib import Path
 from tempfile import TemporaryDirectory
-import time
+from typing import List, Tuple
 
 from zokrates_pycrypto.gadgets.pedersenHasher import PedersenHasher
 

src/vote_cli.py

@@ -9,7 +9,7 @@
 from Crypto.Signature import PKCS1_v1_5
 from web3 import Web3
 
-from provers import ZokratesProver
+from provers import MERKLE_TREE_DEPTH, ZokratesProver, calculate_merkle_tree
 
 VOTE_SERVER = "http://0.0.0.0:5000"
 PROVER = ZokratesProver(Path("."))
@@ -131,6 +131,27 @@ def eth_give_right_to_vote(address: str):
     voting_contract = get_voting_contract(voting_contract_address, w3)
     send_transaction(w3, voting_contract.functions.giveRightToVote(address).build_transaction())
 
+@app.command()
+def eth_set_merkle_root():
+    w3 = Web3(Web3.HTTPProvider(HTTP_ENDPOINT_URL))
+    voting_contract_address = get_deployed_contract_address()
+    voting_contract = get_voting_contract(voting_contract_address, w3)
+
+    num_commits = voting_contract.functions.numCommits().call()
+    known_hashes = []
+    for i in range(num_commits):
+        known_hashes.append(voting_contract.functions.commitList(i).call())
+
+    # This actually computes the Merkle proof for the first commit, but we're only interested in the merkle root
+    print("Computing Merkle root...")
+    merkle_root, _, _ = calculate_merkle_tree(known_hashes, 2 ** MERKLE_TREE_DEPTH, known_hashes[0])
+
+    print(f"Merkle root is: {merkle_root.hex()}")
+    send_transaction(w3, voting_contract.functions.setMerkleRoot(int(merkle_root.hex(), 16)).build_transaction({
+        # Gas estimation fails for some reason, so set limit manually
+        "gas": 2000000
+    }))
+
 @app.command()
 def eth_vote(vote: bool):
 
@@ -185,13 +206,18 @@ def eth_reveal():
     for i in range(num_commits):
         known_hashes.append(voting_contract.functions.commitList(i).call())
 
-    proof, known_hashes = PROVER.compute_proof(serial_number, secret, vote, known_hashes)
+    proof, merkle_root = PROVER.compute_proof(serial_number, secret, vote, known_hashes)
+    print(f"Merkle root is: {merkle_root.hex()}")
+    merkle_root_int = int(merkle_root.hex(), 16)
+    stored_merkle_root = voting_contract.functions.merkleRoot().call()
+    assert stored_merkle_root != 0, "The chairperson has not set the Merkle root yet!"
+    assert stored_merkle_root == merkle_root_int, "Merkle Root is different from what was set by the chairperson!"
 
     def to_ints(hex_str):
         return (int(hex_str[0], 16), int(hex_str[1], 16))
 
     proof_abc = (to_ints(proof["proof"]["a"]), (to_ints(proof["proof"]["b"][0]), to_ints(proof["proof"]["b"][1])), to_ints(proof["proof"]["c"]))
-    tx = voting_contract.functions.revealVote(vote, serial_number, known_hashes, proof_abc).build_transaction()
+    tx = voting_contract.functions.revealVote(vote, serial_number, proof_abc).build_transaction()
     send_transaction(w3, tx)
 
 

test_eth.sh

@@ -5,5 +5,6 @@ python src/vote_cli.py eth-deploy-voting-contract
 # Right to vote for second hardhat account
 #python src/vote_cli.py eth-give-right-to-vote 0x70997970C51812dc3A010C7d01b50e0d17dc79C8
 python src/vote_cli.py eth-vote yes
+python src/vote_cli.py eth-set-merkle-root
 python src/vote_cli.py eth-reveal
 python src/vote_cli.py eth-get-results