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feat: loop-unrolled validator signature set verifier in Yul #700

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mijinummi merged 1 commit into from
Jul 29, 2026
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feat: loop-unrolled validator signature set verifier in Yul #700

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225 changes: 225 additions & 0 deletions contracts/crypto/UnrolledSignatureVerifier.sol
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

/// @title UnrolledSignatureVerifier
/// @notice Gas-optimized ECDSA multi-signature verification with loop-unrolled Yul
/// for fixed thresholds (3-of-5, 5-of-7) and a standard loop reference.
library UnrolledSignatureVerifier {
error InvalidSignatureCount();
error DuplicateSigner();
error ThresholdNotMet();

uint256 private constant MALLEABILITY_THRESHOLD =
0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0;

/// @notice verify3of5 Unrolled 3-of-5 threshold verification.
/// @param hash The signed hash.
/// @param sigs 325 bytes: 5 concatenated ECDSA sigs (65 bytes each: r|s|v).
/// @param validators 5 authorized signers.
function verify3of5(
bytes32 hash,
bytes calldata sigs,
address[5] calldata validators
) external view returns (bool) {
if (sigs.length != 325) revert InvalidSignatureCount();
assembly {
let voff := 0x44
let v0 := calldataload(voff)
let v1 := calldataload(add(voff, 0x20))
let v2 := calldataload(add(voff, 0x40))
let v3 := calldataload(add(voff, 0x60))
let v4 := calldataload(add(voff, 0x80))

if or(eq(v0, v1), or(eq(v0, v2), or(eq(v0, v3), or(eq(v0, v4),
or(eq(v1, v2), or(eq(v1, v3), or(eq(v1, v4),
or(eq(v2, v3), or(eq(v2, v4),
eq(v3, v4)))))))))) {
mstore(0x00, 0x8044bb33)
revert(0x00, 0x04)
}

let soff := sigs.offset

function recover(h, off) -> signer {
let r := calldataload(off)
let s := calldataload(add(off, 0x20))
let vb := byte(0, calldataload(add(off, 0x40)))
if lt(vb, 27) { vb := add(vb, 27) }
let ptr := mload(0x40)
mstore(ptr, h)
mstore(add(ptr, 0x20), vb)
mstore(add(ptr, 0x40), r)
mstore(add(ptr, 0x60), s)
let ok := staticcall(gas(), 0x01, ptr, 0x80, ptr, 0x20)
if iszero(ok) { revert(0, 0) }
signer := mload(ptr)
if iszero(signer) { revert(0, 0) }
}

let s0 := recover(hash, soff)
let s1 := recover(hash, add(soff, 65))
let s2 := recover(hash, add(soff, 130))
let s3 := recover(hash, add(soff, 195))
let s4 := recover(hash, add(soff, 260))

if or(eq(s0, s1), or(eq(s0, s2), or(eq(s0, s3), or(eq(s0, s4),
or(eq(s1, s2), or(eq(s1, s3), or(eq(s1, s4),
or(eq(s2, s3), or(eq(s2, s4),
eq(s3, s4)))))))))) {
mstore(0x00, 0x8044bb33)
revert(0x00, 0x04)
}

let count := 0
if or(eq(s0, v0), or(eq(s0, v1), or(eq(s0, v2), or(eq(s0, v3), eq(s0, v4))))) { count := add(count, 1) }
if or(eq(s1, v0), or(eq(s1, v1), or(eq(s1, v2), or(eq(s1, v3), eq(s1, v4))))) { count := add(count, 1) }
if or(eq(s2, v0), or(eq(s2, v1), or(eq(s2, v2), or(eq(s2, v3), eq(s2, v4))))) { count := add(count, 1) }
if or(eq(s3, v0), or(eq(s3, v1), or(eq(s3, v2), or(eq(s3, v3), eq(s3, v4))))) { count := add(count, 1) }
if or(eq(s4, v0), or(eq(s4, v1), or(eq(s4, v2), or(eq(s4, v3), eq(s4, v4))))) { count := add(count, 1) }

if lt(count, 3) {
mstore(0x00, 0x59fa4a93)
revert(0x00, 0x04)
}

mstore(0x00, 0x01)
return(0x00, 0x20)
}
}

/// @notice verify5of7 Unrolled 5-of-7 threshold verification.
/// @param hash The signed hash.
/// @param sigs 455 bytes: 7 concatenated ECDSA sigs (65 bytes each: r|s|v).
/// @param validators 7 authorized signers.
function verify5of7(
bytes32 hash,
bytes calldata sigs,
address[7] calldata validators
) external view returns (bool) {
if (sigs.length != 455) revert InvalidSignatureCount();
assembly {
let v0 := calldataload(0x44)
let v1 := calldataload(0x64)
let v2 := calldataload(0x84)
let v3 := calldataload(0xA4)
let v4 := calldataload(0xC4)
let v5 := calldataload(0xE4)
let v6 := calldataload(0x104)

if or(eq(v0, v1), or(eq(v0, v2), or(eq(v0, v3), or(eq(v0, v4), or(eq(v0, v5), or(eq(v0, v6),
or(eq(v1, v2), or(eq(v1, v3), or(eq(v1, v4), or(eq(v1, v5), or(eq(v1, v6),
or(eq(v2, v3), or(eq(v2, v4), or(eq(v2, v5), or(eq(v2, v6),
or(eq(v3, v4), or(eq(v3, v5), or(eq(v3, v6),
or(eq(v4, v5), or(eq(v4, v6),
eq(v5, v6)))))))))))))))))))))) {
mstore(0x00, 0x8044bb33)
revert(0x00, 0x04)
}

let soff := sigs.offset

function recover(h, off) -> signer {
let r := calldataload(off)
let s := calldataload(add(off, 0x20))
let vb := byte(0, calldataload(add(off, 0x40)))
if lt(vb, 27) { vb := add(vb, 27) }
let ptr := mload(0x40)
mstore(ptr, h)
mstore(add(ptr, 0x20), vb)
mstore(add(ptr, 0x40), r)
mstore(add(ptr, 0x60), s)
let ok := staticcall(gas(), 0x01, ptr, 0x80, ptr, 0x20)
if iszero(ok) { revert(0, 0) }
signer := mload(ptr)
if iszero(signer) { revert(0, 0) }
}

let s0 := recover(hash, soff)
let s1 := recover(hash, add(soff, 65))
let s2 := recover(hash, add(soff, 130))
let s3 := recover(hash, add(soff, 195))
let s4 := recover(hash, add(soff, 260))
let s5 := recover(hash, add(soff, 325))
let s6 := recover(hash, add(soff, 390))

if or(eq(s0, s1), or(eq(s0, s2), or(eq(s0, s3), or(eq(s0, s4), or(eq(s0, s5), or(eq(s0, s6),
or(eq(s1, s2), or(eq(s1, s3), or(eq(s1, s4), or(eq(s1, s5), or(eq(s1, s6),
or(eq(s2, s3), or(eq(s2, s4), or(eq(s2, s5), or(eq(s2, s6),
or(eq(s3, s4), or(eq(s3, s5), or(eq(s3, s6),
or(eq(s4, s5), or(eq(s4, s6),
eq(s5, s6)))))))))))))))))))))) {
mstore(0x00, 0x8044bb33)
revert(0x00, 0x04)
}

let count := 0
if or(eq(s0, v0), or(eq(s0, v1), or(eq(s0, v2), or(eq(s0, v3), or(eq(s0, v4), or(eq(s0, v5), eq(s0, v6))))))) { count := add(count, 1) }
if or(eq(s1, v0), or(eq(s1, v1), or(eq(s1, v2), or(eq(s1, v3), or(eq(s1, v4), or(eq(s1, v5), eq(s1, v6))))))) { count := add(count, 1) }
if or(eq(s2, v0), or(eq(s2, v1), or(eq(s2, v2), or(eq(s2, v3), or(eq(s2, v4), or(eq(s2, v5), eq(s2, v6))))))) { count := add(count, 1) }
if or(eq(s3, v0), or(eq(s3, v1), or(eq(s3, v2), or(eq(s3, v3), or(eq(s3, v4), or(eq(s3, v5), eq(s3, v6))))))) { count := add(count, 1) }
if or(eq(s4, v0), or(eq(s4, v1), or(eq(s4, v2), or(eq(s4, v3), or(eq(s4, v4), or(eq(s4, v5), eq(s4, v6))))))) { count := add(count, 1) }
if or(eq(s5, v0), or(eq(s5, v1), or(eq(s5, v2), or(eq(s5, v3), or(eq(s5, v4), or(eq(s5, v5), eq(s5, v6))))))) { count := add(count, 1) }
if or(eq(s6, v0), or(eq(s6, v1), or(eq(s6, v2), or(eq(s6, v3), or(eq(s6, v4), or(eq(s6, v5), eq(s6, v6))))))) { count := add(count, 1) }

if lt(count, 5) {
mstore(0x00, 0x59fa4a93)
revert(0x00, 0x04)
}

mstore(0x00, 0x01)
return(0x00, 0x20)
}
}

/// @notice verifyThreshold Standard loop-based threshold verification (reference).
/// @param hash The signed hash.
/// @param sigs Array of ECDSA signatures (each 65 bytes).
/// @param validators Array of authorized signers.
/// @param threshold Minimum number of matching signatures required.
function verifyThreshold(
bytes32 hash,
bytes[] calldata sigs,
address[] calldata validators,
uint256 threshold
) external view returns (bool) {
uint256 n = sigs.length;
if (n != validators.length) revert InvalidSignatureCount();
if (threshold > n) revert InvalidSignatureCount();

for (uint256 i = 0; i < validators.length; i++) {
for (uint256 j = i + 1; j < validators.length; j++) {
if (validators[i] == validators[j]) revert DuplicateSigner();
}
}

address[] memory recovered = new address[](n);
for (uint256 i = 0; i < n; i++) {
bytes calldata sig = sigs[i];
if (sig.length != 65) revert InvalidSignatureCount();
bytes32 r = bytes32(sig[0:32]);
bytes32 s = bytes32(sig[32:64]);
uint8 v = uint8(sig[64]);
if (uint256(s) > MALLEABILITY_THRESHOLD) revert InvalidSignatureCount();
if (v < 27) v += 27;
address signer = ecrecover(hash, v, r, s);
if (signer == address(0)) revert InvalidSignatureCount();
for (uint256 k = 0; k < i; k++) {
if (recovered[k] == signer) revert DuplicateSigner();
}
recovered[i] = signer;
}

uint256 count;
for (uint256 i = 0; i < n; i++) {
for (uint256 j = 0; j < validators.length; j++) {
if (recovered[i] == validators[j]) {
count++;
break;
}
}
}

if (count < threshold) revert ThresholdNotMet();
return true;
}
}
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