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Merge pull request #15 from peppersec/audit-circuit

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Circuit audit fixes
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Roman Semenov 2019-11-06 12:31:23 +03:00 committed by GitHub
commit b000e66899
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 44 additions and 81 deletions
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65
circuits/merkleTree.circom
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@ -1,72 +1,49 @@
include "../node_modules/circomlib/circuits/mimcsponge.circom";
// Computes MiMC(left + right)
template HashLeftRight(rounds) {
// Computes MiMC([left, right])
template HashLeftRight() {
signal input left;
signal input right;
signal output hash;
component hasher = MiMCSponge(2, rounds, 1);
component hasher = MiMCSponge(2, 220, 1);
hasher.ins[0] <== left;
hasher.ins[1] <== right;
hasher.k <== 0;
hash <== hasher.outs[0];
}
// if pathIndex == 0 returns (left = inputElement, right = pathElement)
// if pathIndex == 1 returns (left = pathElement, right = inputElement)
template Selector() {
signal input inputElement;
signal input pathElement;
signal input pathIndex;
// if s == 0 returns [in[0], in[1]]
// if s == 1 returns [in[1], in[0]]
template Mux() {
signal input in[2];
signal input s;
signal output out[2];
signal output left;
signal output right;
signal leftSelector1;
signal leftSelector2;
signal rightSelector1;
signal rightSelector2;
pathIndex * (1-pathIndex) === 0
leftSelector1 <== (1 - pathIndex) * inputElement;
leftSelector2 <== (pathIndex) * pathElement;
rightSelector1 <== (pathIndex) * inputElement;
rightSelector2 <== (1 - pathIndex) * pathElement;
left <== leftSelector1 + leftSelector2;
right <== rightSelector1 + rightSelector2;
out[0] <== (in[1] - in[0])*s + in[0];
out[1] <== (in[0] - in[1])*s + in[1];
}
// Verifies that merkle proof is correct for given merkle root and a leaf
// pathIndex input is an array of 0/1 selectors telling whether given pathElement is on the left or right side of merkle path
template MerkleTree(levels, rounds) {
// pathIndices input is an array of 0/1 selectors telling whether given pathElement is on the left or right side of merkle path
template MerkleTree(levels) {
signal input leaf;
signal input root;
signal private input pathElements[levels];
signal private input pathIndex[levels];
signal private input pathIndices[levels];
component selectors[levels];
component hashers[levels];
for (var i = 0; i < levels; i++) {
selectors[i] = Selector();
hashers[i] = HashLeftRight(rounds);
selectors[i] = Mux();
selectors[i].in[0] <== i == 0 ? leaf : hashers[i - 1].hash;
selectors[i].in[1] <== pathElements[i];
selectors[i].s <== pathIndices[i];
selectors[i].pathElement <== pathElements[i];
selectors[i].pathIndex <== pathIndex[i];
hashers[i].left <== selectors[i].left;
hashers[i].right <== selectors[i].right;
}
selectors[0].inputElement <== leaf;
for (var i = 1; i < levels; i++) {
selectors[i].inputElement <== hashers[i-1].hash;
hashers[i] = HashLeftRight();
hashers[i].left <== selectors[i].out[0];
hashers[i].right <== selectors[i].out[1];
}
root === hashers[levels - 1].hash;

32
circuits/withdraw.circom
View File

@ -6,7 +6,6 @@ include "merkleTree.circom";
template CommitmentHasher() {
signal private input nullifier;
signal private input secret;
signal output commitment;
signal output nullifierHash;
@ -27,43 +26,30 @@ template CommitmentHasher() {
}
// Verifies that commitment that corresponds to given secret and nullifier is included in the merkle tree of deposits
template Withdraw(levels, rounds) {
template Withdraw(levels) {
signal input root;
signal input nullifierHash;
signal input receiver; // not taking part in any computations
signal input relayer; // not taking part in any computations
signal input fee; // not taking part in any computations
signal input refund; // not taking part in any computations
signal input relayer; // not taking part in any computations
signal input fee; // not taking part in any computations
signal input refund; // not taking part in any computations
signal private input nullifier;
signal private input secret;
signal private input pathElements[levels];
signal private input pathIndex[levels];
signal private input pathIndices[levels];
component hasher = CommitmentHasher();
hasher.nullifier <== nullifier;
hasher.secret <== secret;
hasher.nullifierHash === nullifierHash;
nullifierHash === hasher.nullifierHash;
component tree = MerkleTree(levels, rounds);
component tree = MerkleTree(levels);
tree.leaf <== hasher.commitment;
tree.root <== root;
for (var i = 0; i < levels; i++) {
tree.pathElements[i] <== pathElements[i];
tree.pathIndex[i] <== pathIndex[i];
tree.pathIndices[i] <== pathIndices[i];
}
// Add hidden signals to make sure that tampering with receiver or fee will invalidate the snark proof
// Most likely it is not required, but it's better to stay on the safe side and it only takes 2 constraints
// Squares are used to prevent optimizer from removing those constraints
signal receiverSquare;
signal feeSquare;
signal relayerSquare;
signal refundSquare;
receiverSquare <== receiver * receiver;
feeSquare <== fee * fee;
relayerSquare <== relayer * relayer;
refundSquare <== refund * refund;
}
component main = Withdraw(16, 220);
component main = Withdraw(16);

4
cli.js
View File

@ -107,7 +107,7 @@ async function withdrawErc20(note, receiver, relayer) {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
}
console.log('Generating SNARK proof')
@ -182,7 +182,7 @@ async function withdraw(note, receiver) {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
}
console.log('Generating SNARK proof')

8
test/ERC20Mixer.test.js
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@ -142,7 +142,7 @@ contract('ERC20Mixer', accounts => {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
@ -210,7 +210,7 @@ contract('ERC20Mixer', accounts => {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
@ -269,7 +269,7 @@ contract('ERC20Mixer', accounts => {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
@ -350,7 +350,7 @@ contract('ERC20Mixer', accounts => {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})

16
test/ETHMixer.test.js
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@ -150,7 +150,7 @@ contract('ETHMixer', accounts => {
refund,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
let proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)
@ -210,7 +210,7 @@ contract('ETHMixer', accounts => {
nullifier: deposit.nullifier,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
@ -265,7 +265,7 @@ contract('ETHMixer', accounts => {
refund,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
const proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)
const { proof, publicSignals } = websnarkUtils.toSolidityInput(proofData)
@ -291,7 +291,7 @@ contract('ETHMixer', accounts => {
refund,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
const proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)
const { proof, publicSignals } = websnarkUtils.toSolidityInput(proofData)
@ -317,7 +317,7 @@ contract('ETHMixer', accounts => {
refund,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
const proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)
@ -343,7 +343,7 @@ contract('ETHMixer', accounts => {
refund,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
const dummyRoot = randomHex(32)
@ -372,7 +372,7 @@ contract('ETHMixer', accounts => {
refund,
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
const proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)
let { proof, publicSignals } = websnarkUtils.toSolidityInput(proofData)
@ -424,7 +424,7 @@ contract('ETHMixer', accounts => {
refund: bigInt(1),
secret: deposit.secret,
pathElements: path_elements,
pathIndex: path_index,
pathIndices: path_index,
})
const proofData = await websnarkUtils.genWitnessAndProve(groth16, input, circuit, proving_key)