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37 lines
1.2 KiB
Solidity
37 lines
1.2 KiB
Solidity
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//SPDX-License-Identifier: AGPLv3
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pragma solidity ^0.8.0;
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// see https://github.com/noot/schnorr-verify for implementation details
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contract Schnorr {
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// secp256k1 group order
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uint256 constant public Q =
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0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141;
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// parity := public key y-coord parity (27 or 28)
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// px := public key x-coord
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// message := 32-byte message
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// s := schnorr signature
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// e := schnorr signature challenge
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function verify(
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uint8 parity,
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bytes32 px,
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bytes32 message,
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bytes32 s,
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bytes32 e
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) public view returns (bool) {
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// ecrecover = (m, v, r, s);
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bytes32 sp = bytes32(Q - mulmod(uint256(s), uint256(px), Q));
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bytes32 ep = bytes32(Q - mulmod(uint256(e), uint256(px), Q));
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require(sp != 0);
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// the ecrecover precompile implementation checks that the `r` and `s`
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// inputs are non-zero (in this case, `px` and `ep`), thus we don't need to
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// check if they're zero.will make me
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address R = ecrecover(sp, parity, px, ep);
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require(R != address(0), "ecrecover failed");
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return e == keccak256(
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abi.encodePacked(R, uint8(parity), px, block.chainid, message)
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);
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}
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}
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