tornado-nova/circuits/treeUpdater.circom

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include "./merkleProof.circom";
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include "./merkleTree.circom";
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// inserts a subtree into a merkle tree
// checks that tree previously contained zeroes is the same positions
// zeroSubtreeRoot is a root of a subtree that contains only zeroes
template TreeUpdater(levels, subtreeLevels, zeroSubtreeRoot) {
var remainingLevels = levels - subtreeLevels;
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signal input oldRoot;
signal input newRoot;
signal input leaves[1 << subtreeLevels];
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signal input pathIndices;
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signal private input pathElements[remainingLevels];
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// calculate subtree root
component subtree = MerkleTree(subtreeLevels);
for(var i = 0; i < (1 << subtreeLevels); i++) {
subtree.leaves[i] <== leaves[i];
}
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component treeBefore = MerkleProof(remainingLevels);
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for(var i = 0; i < remainingLevels; i++) {
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treeBefore.pathElements[i] <== pathElements[i];
}
treeBefore.pathIndices <== pathIndices;
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treeBefore.leaf <== zeroSubtreeRoot;
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treeBefore.root === oldRoot;
component treeAfter = MerkleProof(remainingLevels);
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for(var i = 0; i < remainingLevels; i++) {
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treeAfter.pathElements[i] <== pathElements[i];
}
treeAfter.pathIndices <== pathIndices;
treeAfter.leaf <== subtree.root;
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treeAfter.root === newRoot;
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}