73 lines
2.0 KiB
Plaintext
73 lines
2.0 KiB
Plaintext
include "../node_modules/circomlib/circuits/poseidon.circom";
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// Computes Poseidon(left + right)
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template HashLeftRight(rounds) {
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signal input left;
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signal input right;
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signal output hash;
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component hasher = Poseidon(2, 3, 8, 57);
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hasher.inputs[0] <== left;
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hasher.inputs[1] <== right;
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hash <== hasher.out;
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}
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// if pathIndex == 0 returns (left = inputElement, right = pathElement)
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// if pathIndex == 1 returns (left = pathElement, right = inputElement)
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template Selector() {
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signal input inputElement;
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signal input pathElement;
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signal input pathIndex;
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signal output left;
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signal output right;
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signal leftSelector1;
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signal leftSelector2;
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signal rightSelector1;
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signal rightSelector2;
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pathIndex * (1-pathIndex) === 0
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leftSelector1 <== (1 - pathIndex) * inputElement;
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leftSelector2 <== (pathIndex) * pathElement;
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rightSelector1 <== (pathIndex) * inputElement;
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rightSelector2 <== (1 - pathIndex) * pathElement;
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left <== leftSelector1 + leftSelector2;
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right <== rightSelector1 + rightSelector2;
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}
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// Verifies that merkle proof is correct for given merkle root and a leaf
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// pathIndex input is an array of 0/1 selectors telling whether given pathElement is on the left or right side of merkle path
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template MerkleTree(levels, rounds) {
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signal input leaf;
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signal input root;
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signal private input pathElements[levels];
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signal private input pathIndex[levels];
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component selectors[levels];
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component hashers[levels];
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for (var i = 0; i < levels; i++) {
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selectors[i] = Selector();
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hashers[i] = HashLeftRight(rounds);
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selectors[i].pathElement <== pathElements[i];
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selectors[i].pathIndex <== pathIndex[i];
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hashers[i].left <== selectors[i].left;
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hashers[i].right <== selectors[i].right;
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}
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selectors[0].inputElement <== leaf;
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for (var i = 1; i < levels; i++) {
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selectors[i].inputElement <== hashers[i-1].hash;
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}
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root === hashers[levels - 1].hash;
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}
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