72 lines
1.9 KiB
Plaintext
72 lines
1.9 KiB
Plaintext
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include "../node_modules/circomlib/circuits/poseidon.circom";
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include "../node_modules/circomlib/circuits/bitify.circom";
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// Computes Poseidon([left, right])
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template HashLeftRight() {
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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);
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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 s == 0 returns [in[0], in[1]]
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// if s == 1 returns [in[1], in[0]]
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template DualMux() {
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signal input in[2];
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signal input s;
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signal output out[2];
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s * (1 - s) === 0;
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out[0] <== (in[1] - in[0])*s + in[0];
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out[1] <== (in[0] - in[1])*s + in[1];
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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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// pathIndices 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 RawMerkleTree(levels) {
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signal input leaf;
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signal input pathElements[levels];
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signal input pathIndices[levels];
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signal output root;
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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] = DualMux();
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selectors[i].in[0] <== i == 0 ? leaf : hashers[i - 1].hash;
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selectors[i].in[1] <== pathElements[i];
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selectors[i].s <== pathIndices[i];
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hashers[i] = HashLeftRight();
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hashers[i].left <== selectors[i].out[0];
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hashers[i].right <== selectors[i].out[1];
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}
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root <== hashers[levels - 1].hash;
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}
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template MerkleTree(levels) {
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signal input leaf;
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signal input pathElements[levels];
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signal input pathIndices;
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signal output root;
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component indexBits = Num2Bits(levels);
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indexBits.in <== pathIndices;
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component tree = RawMerkleTree(levels)
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tree.leaf <== leaf;
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for (var i = 0; i < levels; i++) {
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tree.pathIndices[i] <== indexBits.out[i];
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tree.pathElements[i] <== pathElements[i];
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}
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root <== tree.root
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}
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