added require revert strings to contracts; modified semaphore contract test to check for said strings (#21)

upgraded snarkjs commit hash

added revert reason test for verifier-gte-snark-scalar-field

updated package-lock.json and circleci snark file cache

Former-commit-id: ca9dbb7f98

.circleci/config.yml

@@ -19,14 +19,14 @@ jobs:
       - restore_cache:
           name: restore-npm-cache
           keys:
-            - v1.6-dependencies-{{ checksum "package-lock.json" }}
+            - v1.7-dependencies-{{ checksum "package-lock.json" }}
 
       - run: npm install
 
       - save_cache:
           paths:
             - node_modules
-          key: v1.6-dependencies-{{ checksum "package-lock.json" }}
+          key: v1.7-dependencies-{{ checksum "package-lock.json" }}
 
       # checksum the snarks definitions
       - run:
@@ -37,7 +37,7 @@ jobs:
       - restore_cache:
           name: restore-snark-cache
           keys:
-            - v1.6-dependencies-{{ checksum "build/.snark_checksum" }}
+            - v1.7-dependencies-{{ checksum "build/.snark_checksum" }}
 
       # build snarks
       - run:
@@ -47,7 +47,7 @@ jobs:
 
       # cache generated snark circuit and keys
       - save_cache:
-          key: v1.6-dependencies-{{ checksum "build/.snark_checksum" }}
+          key: v1.7-dependencies-{{ checksum "build/.snark_checksum" }}
           paths:
             - build/circuit.json
             - build/proving_key.bin

semaphorejs/contracts/MerkleTreeLib.sol

@@ -129,7 +129,7 @@ contract MultipleMerkleTree {
             current_index /= 2;
         }
 
-        require(tree_roots[tree_index] == current_level_hash);
+        require(tree_roots[tree_index] == current_level_hash, "MultipleMerkleTree: tree root / current level hash mismatch");
 
         current_index = leaf_index;
 

semaphorejs/contracts/Semaphore.sol

@@ -82,6 +82,20 @@ contract Semaphore is Verifier, MultipleMerkleTree, Ownable {
             verifyProof(a, b, c, input);
     }
 
+    function preBroadcastRequire (
+        uint[2] memory a,
+        uint[2][2] memory b,
+        uint[2] memory c,
+        uint[5] memory input,
+        uint256 signal_hash
+    ) public {
+        require(hasNullifier(input[1]) == false, "Semaphore: nullifier already seen");
+        require(signal_hash == input[2], "Semaphore: signal hash mismatch");
+        require(external_nullifier == input[3], "Semaphore: external nullifier mismatch");
+        require(isInRootHistory(input[0]), "Semaphore: root not seen");
+        require(verifyProof(a, b, c, input), "Semaphore: invalid proof");
+    }
+
     function broadcastSignal(
         bytes memory signal,
         uint[2] memory a,
@@ -89,14 +103,15 @@ contract Semaphore is Verifier, MultipleMerkleTree, Ownable {
         uint[2] memory c,
         uint[5] memory input // (root, nullifiers_hash, signal_hash, external_nullifier, broadcaster_address)
     ) public {
+        // Hash the signal
         uint256 signal_hash = uint256(sha256(signal)) >> 8;
 
         // Check the inputs
-        require(preBroadcastCheck(a, b, c, input, signal_hash) == true);
+        preBroadcastRequire(a, b, c, input, signal_hash);
 
         // Verify the broadcaster's address
         address broadcaster = address(input[4]);
-        require(broadcaster == msg.sender);
+        require(broadcaster == msg.sender, "Semaphore: wrong broadcaster's address");
 
         signals[current_signal_index++] = signal;
         nullifiers_set[input[1]] = true;

semaphorejs/package-lock.json.REMOVED.git-id

@@ -1 +1 @@
-39124ef55318abd5836f3deab4a24e5f8854c840
+6cc0f357770fdccb6bb3309b36820135fac84434

semaphorejs/package.json

@@ -33,7 +33,7 @@
     "node-fetch": "^2.3.0",
     "require-nocache": "^1.0.0",
     "semaphore-merkle-tree": "^1.0.4",
-    "snarkjs": "git+https://github.com/iden3/snarkjs.git#f8ba7cbfa7d526e186fd3a706be00f63b65812d8",
+    "snarkjs": "git+https://github.com/iden3/snarkjs.git#c428706ef69930e378c31199ff8d66ee13fada85",
     "truffle": "^5.0.10",
     "truffle-artifactor": "^4.0.10",
     "truffle-contract": "^4.0.11",

semaphorejs/test/contracts/semaphore.js

@@ -190,6 +190,8 @@ contract('Semaphore', function (accounts) {
         const publicSignals = w.slice(1, circuit.nPubInputs + circuit.nOutputs+1);
         const proof = await proof_util.prove(witness_bin.buffer, vk_proof.buffer);
         let failed = false;
+        let reason = '';
+
         try {
           await semaphore.broadcastSignal(
               signal_to_contract,
@@ -200,8 +202,10 @@ contract('Semaphore', function (accounts) {
           );
         } catch(e) {
           failed = true;
+          reason = e.reason
         }
         assert.equal(failed, true);
+        assert.equal(reason, 'Semaphore: root not seen');
 
         failed = false;
         try {
@@ -214,8 +218,10 @@ contract('Semaphore', function (accounts) {
           );
         } catch(e) {
           failed = true;
+          reason = e.reason
         }
         assert.equal(failed, true);
+        assert.equal(reason, 'verifier-gte-snark-scalar-field');
 
         const a = [ proof.pi_a[0].toString(), proof.pi_a[1].toString() ]
         const b = [ [ proof.pi_b[0][1].toString(), proof.pi_b[0][0].toString() ], [ proof.pi_b[1][1].toString(), proof.pi_b[1][0].toString() ] ]