feat(qv): add optional flag to use quadratic voting or not in MACI

Amend all parts of the code to support both quadratic and non quadratic voting. Circuits for non
quadratic voting have a slight reduction in constraints (especially processMessages). Tests added
for the feature in both cli e2e, core e2e and unit, and circuits unit tests.

circuits/circom/circuits.json

@@ -5,12 +5,24 @@
     "params": [10, 2, 1, 2],
     "pubs": ["inputHash"]
   },
+  "ProcessMessagesNonQv_10-2-1-2_test": {
+    "file": "processMessagesNonQv",
+    "template": "ProcessMessagesNonQv",
+    "params": [10, 2, 1, 2],
+    "pubs": ["inputHash"]
+  },
   "TallyVotes_10-1-2_test": {
     "file": "tallyVotes",
     "template": "TallyVotes",
     "params": [10, 1, 2],
     "pubs": ["inputHash"]
   },
+  "TallyVotesNonQv_10-1-2_test": {
+    "file": "tallyVotesNonQv",
+    "template": "TallyVotesNonQv",
+    "params": [10, 1, 2],
+    "pubs": ["inputHash"]
+  },
   "SubsidyPerBatch_10-1-2_test": {
     "file": "subsidy",
     "template": "SubsidyPerBatch",

circuits/circom/messageValidatorNonQv.circom

@@ -0,0 +1,84 @@
+pragma circom 2.0.0;
+
+// local imports
+include "./verifySignature.circom";
+include "./utils.circom";
+
+// template that validates whether a message
+// is valid or not 
+// @note it does not do quadratic voting
+template MessageValidatorNonQv() {
+    // a) Whether the state leaf index is valid
+    signal input stateTreeIndex;
+    // how many signups we have in the state tree
+    signal input numSignUps;
+    // we check that the state tree index is <= than the number of signups
+    // as first validation
+    // it is <= because the state tree index is 1-based
+    // 0 is for blank state leaf then 1 for the first actual user
+    // which is where the numSignUps starts
+    component validStateLeafIndex = SafeLessEqThan(252);
+    validStateLeafIndex.in[0] <== stateTreeIndex;
+    validStateLeafIndex.in[1] <== numSignUps;
+
+    // b) Whether the max vote option tree index is correct
+    signal input voteOptionIndex;
+    signal input maxVoteOptions;
+    component validVoteOptionIndex = SafeLessThan(252);
+    validVoteOptionIndex.in[0] <== voteOptionIndex;
+    validVoteOptionIndex.in[1] <== maxVoteOptions;
+
+    // c) Whether the nonce is correct
+    signal input originalNonce;
+    signal input nonce;
+    component validNonce = IsEqual();
+    // the nonce should be previous nonce + 1
+    validNonce.in[0] <== originalNonce + 1;
+    validNonce.in[1] <== nonce;
+
+    var PACKED_CMD_LENGTH = 4;
+    // d) Whether the signature is correct
+    signal input cmd[PACKED_CMD_LENGTH];
+    signal input pubKey[2];
+    signal input sigR8[2];
+    signal input sigS;
+
+    component validSignature = VerifySignature();
+    validSignature.pubKey[0] <== pubKey[0];
+    validSignature.pubKey[1] <== pubKey[1];
+    validSignature.R8[0] <== sigR8[0];
+    validSignature.R8[1] <== sigR8[1];
+    validSignature.S <== sigS;
+    for (var i = 0; i < PACKED_CMD_LENGTH; i ++) {
+        validSignature.preimage[i] <== cmd[i];
+    }
+
+    // e) Whether the state leaf was inserted before the Poll period ended
+    signal input slTimestamp;
+    signal input pollEndTimestamp;
+    component validTimestamp = SafeLessEqThan(252);
+    validTimestamp.in[0] <== slTimestamp;
+    validTimestamp.in[1] <== pollEndTimestamp;
+
+    // f) Whether there are sufficient voice credits
+    signal input currentVoiceCreditBalance;
+    signal input currentVotesForOption;
+    signal input voteWeight;
+
+    // Check that currentVoiceCreditBalance + (currentVotesForOption) >= (voteWeight)
+    component sufficientVoiceCredits = SafeGreaterEqThan(252);
+    sufficientVoiceCredits.in[0] <== currentVotesForOption + currentVoiceCreditBalance;
+    sufficientVoiceCredits.in[1] <== voteWeight;
+
+    // if all 7 checks are correct then is IsValid = 1
+    component validUpdate = IsEqual();
+    validUpdate.in[0] <== 6;
+    validUpdate.in[1] <== validSignature.valid + 
+                          sufficientVoiceCredits.out +
+                          validNonce.out +
+                          validStateLeafIndex.out +
+                          validTimestamp.out +
+                          validVoteOptionIndex.out;
+    signal output isValid;
+    isValid <== validUpdate.out;
+}