ZKP-License-System/zkp-service/circuits/license_verification.circom

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pragma circom 2.0.0;
include "../node_modules/circomlib/circuits/poseidon.circom";
include "../node_modules/circomlib/circuits/comparators.circom";
include "../node_modules/circomlib/circuits/switcher.circom";
include "../node_modules/circomlib/circuits/bitify.circom";
// Merkle tree inclusion proof verifier
template MerkleTreeChecker(levels) {
signal input leaf;
signal input root;
signal input pathElements[levels];
signal input pathIndices[levels];
component selectors[levels];
component hashers[levels];
signal computedPath[levels + 1];
computedPath[0] <== leaf;
for (var i = 0; i < levels; i++) {
selectors[i] = Switcher();
selectors[i].sel <== pathIndices[i];
selectors[i].L <== computedPath[i];
selectors[i].R <== pathElements[i];
hashers[i] = Poseidon(2);
hashers[i].inputs[0] <== selectors[i].outL;
hashers[i].inputs[1] <== selectors[i].outR;
computedPath[i + 1] <== hashers[i].out;
}
// DEBUG OUTPUTS - expose both values
signal output debugExpectedRoot;
signal output debugComputedRoot;
debugExpectedRoot <== root;
debugComputedRoot <== computedPath[levels];
// Temporarily comment out assertion
//just generate proof done exclude yet
//root === computedPath[levels];
}
template LicenseVerification(merkleTreeLevels) {
// Private inputs - these remain hidden
signal input licenseNumber;
signal input practitionerName;
signal input issuedDate;
signal input expiryDate;
signal input jurisdiction;
signal input pathElements[merkleTreeLevels];
signal input pathIndices[merkleTreeLevels];
// Public inputs - these are revealed
signal input merkleRoot;
signal input currentTimestamp;
signal input minExpiryTimestamp; // Proves license valid at least until this date
// Hash the license data to create the leaf
component hasher = Poseidon(5);
hasher.inputs[0] <== licenseNumber;
hasher.inputs[1] <== practitionerName;
hasher.inputs[2] <== issuedDate;
hasher.inputs[3] <== expiryDate;
hasher.inputs[4] <== jurisdiction;
signal leaf <== hasher.out;
// Verify the license is in the Merkle tree
component merkleChecker = MerkleTreeChecker(merkleTreeLevels);
merkleChecker.leaf <== leaf;
merkleChecker.root <== merkleRoot;
for (var i = 0; i < merkleTreeLevels; i++) {
merkleChecker.pathElements[i] <== pathElements[i];
merkleChecker.pathIndices[i] <== pathIndices[i];
}
// Check license is not expired
component notExpired = GreaterThan(32);
notExpired.in[0] <== expiryDate;
notExpired.in[1] <== currentTimestamp;
// Check license is valid for at least the minimum required period
component validUntilMin = GreaterEqThan(32);
validUntilMin.in[0] <== expiryDate;
validUntilMin.in[1] <== minExpiryTimestamp;
// Check license was issued before current time (sanity check)
component wasIssued = LessThan(32);
wasIssued.in[0] <== issuedDate;
wasIssued.in[1] <== currentTimestamp;
// All checks must pass
signal output isValid;
isValid <== notExpired.out * validUntilMin.out; // * wasIssued.out;
signal output debugExpectedRoot;
signal output debugComputedRoot;
debugExpectedRoot <== merkleChecker.debugExpectedRoot;
debugComputedRoot <== merkleChecker.debugComputedRoot;
}
// Main component with 17 levels (supports ~132k licenses)
component main {public [merkleRoot, currentTimestamp, minExpiryTimestamp]} = LicenseVerification(17);