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Merged
Amxx merged 17 commits into from
Apr 3, 2025
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Fix issue with detection of RIP7212 precompile #5620

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c0632e0
Fix issue with detection of RIP7212 precompile
Amxx Apr 2, 2025
7edf9f6
add changeset
Amxx Apr 2, 2025
b3d2219
test using hardhat 2.22.7 support for rip-7212
Amxx Apr 2, 2025
3f58714
Apply suggestions from code review
Amxx Apr 2, 2025
88fd7ad
Update contracts/utils/cryptography/P256.sol
Amxx Apr 2, 2025
65b1a53
Update contracts/utils/cryptography/P256.sol
Amxx Apr 2, 2025
a2e2d65
rename erc7212 to rip7212
Amxx Apr 2, 2025
174db70
Update contracts/utils/cryptography/P256.sol
Amxx Apr 2, 2025
670b858
Update .changeset/mighty-melons-cheer.md
Amxx Apr 2, 2025
5e7f44b
Update mighty-melons-cheer.md
Amxx Apr 2, 2025
2627809
use valid signature from Wycheproof and optimize _rip7212
Amxx Apr 2, 2025
a0da59a
Apply suggestions from code review
Amxx Apr 2, 2025
a2a0bf2
Update contracts/utils/cryptography/P256.sol
Amxx Apr 2, 2025
dcac7dd
Update contracts/utils/cryptography/P256.sol
ernestognw Apr 2, 2025
7478900
fix test case
Amxx Apr 2, 2025
111a0a4
Improve coverage and include PR comments
ernestognw Apr 3, 2025
f640dca
Update .changeset/mighty-melons-cheer.md
Amxx Apr 3, 2025
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5 changes: 5 additions & 0 deletions .changeset/mighty-melons-cheer.md
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@@ -0,0 +1,5 @@
---
'openzeppelin-solidity': patch
---

`P256`: Fix precompile detection, avoiding revert in `verifyNative`, and reducing cost of `verify` when the signature is invalid.
36 changes: 34 additions & 2 deletions contracts/utils/cryptography/P256.sol
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Expand Up @@ -90,10 +90,42 @@ library P256 {
) private view returns (bool valid, bool supported) {
if (!_isProperSignature(r, s) || !isValidPublicKey(qx, qy)) {
return (false, true); // signature is invalid, and its not because the precompile is missing
} else if (_rip7212(h, r, s, qx, qy)) {
return (true, true); // precompile is present, signature is valid
} else if (
_rip7212(
0x4cee90eb86eaa050036147a12d49004b6b9c72bd725d39d4785011fe190f0b4d,
0xa73bd4903f0ce3b639bbbf6e8e80d16931ff4bcf5993d58468e8fb19086e8cac,
0x36dbcd03009df8c59286b162af3bd7fcc0450c9aa81be5d10d312af6c66b1d60,
0x4aebd3099c618202fcfe16ae7770b0c49ab5eadf74b754204a3bb6060e44eff3,
0x7618b065f9832de4ca6ca971a7a1adc826d0f7c00181a5fb2ddf79ae00b4e10e
)
) {
return (false, true); // precompile is present, signature is invalid
} else {
return (false, false); // precompile is absent
}
}

(bool success, bytes memory returndata) = address(0x100).staticcall(abi.encode(h, r, s, qx, qy));
return (success && returndata.length == 0x20) ? (abi.decode(returndata, (bool)), true) : (false, false);
/**
* @dev Low level helper for {_tryVerifyNative}. Calls the precompile and checks if there is a return value.
*
* Note: According to RIP-7212, invalid signature are indistinguishable from the absence of the precompile.
* Getting the success boolean, copying the returndata to memory, and loading it as a boolean, is not strictly
* necessary, but it protects against non-standard implementations that would return 0 (false) for
* invalid signatures.
*/
function _rip7212(bytes32 h, bytes32 r, bytes32 s, bytes32 qx, bytes32 qy) private view returns (bool isValid) {
assembly ("memory-safe") {
let ptr := mload(0x40)
mstore(ptr, h)
mstore(add(ptr, 0x20), r)
mstore(add(ptr, 0x40), s)
mstore(add(ptr, 0x60), qx)
mstore(add(ptr, 0x80), qy)
let success := staticcall(gas(), 0x100, ptr, 0xa0, 0x00, 0x20)
isValid := and(success, and(eq(returndatasize(), 0x20), eq(mload(0), 1)))
}
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@Vectorized Vectorized Apr 2, 2025 •
edited
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Just a little paranoid on the gas estimation part.

// The `invalid` upon `staticcall` failure is solely for gas estimation.
// When given sufficient gas, the precompile will not revert.
if iszero(staticcall(gas(), 0x100, m, 0xa0, 0x00, 0x00)) { invalid() }
// The precompile will only return `uint256(1)` if and only if the signature is valid.
// As per latest spec, verified against the op-geth implementation:
// See: https://github.com/ethereum-optimism/op-geth/blob/02dfe8692a3c606dbabd83c1ced2037aab9753d7/core/vm/contracts.go#L1342
// Otherwise, it will always return no data.
isValid := iszero(iszero(returndatasize()))

More conservative (in case the spec and implementations are somehow edited again):

// The `invalid` upon `staticcall` failure is solely for gas estimation.
// When given sufficient gas, the precompile will not revert.
mstore(0x00, 0) // Zeroize the slot for the returndata.
if iszero(staticcall(gas(), 0x100, m, 0xa0, 0x00, 0x20)) { invalid() }
// The precompile will only return `uint256(1)` if and only if the signature is valid.
// As per latest spec, verified against the op-geth implementation:
// See: https://github.com/ethereum-optimism/op-geth/blob/02dfe8692a3c606dbabd83c1ced2037aab9753d7/core/vm/contracts.go#L1342
// Otherwise, it will always return no data.
isValid := mload(0x00)

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@Amxx Amxx Apr 2, 2025 •
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I'd like to avoid the invalid() here. I think its better if the function returns false instead of reverting if we are in a strange situation where the precompile acts eraticly. But again, if the precompile revert ... maybe something very fishy is going on and its ok to fail.

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@Amxx Amxx Apr 2, 2025

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also, aren't ifs quite expensive compared to basic and operations?

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@Amxx Amxx Apr 2, 2025

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should we worry about the precompile returning something that is neither 0 nor 1 ?

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@Vectorized Vectorized Apr 2, 2025

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I think we don't need to worry about it.

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@ernestognw ernestognw Apr 2, 2025

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I like @Vectorized's idea since the library is designed to work with RIP-7212 so it should be safe to assume that all implementations would be compliant (i.e. returning empty bytes on failed verification). We can add a note so that developers can just override the function and manually check the returndata, but I'm afraid the consequences of missing such note would be pretty bad.

}

/**
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1 change: 1 addition & 0 deletions hardhat.config.js
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Expand Up @@ -102,6 +102,7 @@ module.exports = {
// we rely on the `code-size` compiler warning, that will cause a compilation error.
allowUnlimitedContractSize: true,
initialBaseFeePerGas: argv.coverage ? 0 : undefined,
enableRip7212: true,
},
},
exposed: {
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