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Add support for EIP2098 "short signatures" in the ECDSA library (#2582)

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Co-authored-by: Francisco Giordano <frangio.1@gmail.com>
This commit is contained in:
Hadrien Croubois
2021-04-10 00:58:03 +02:00
committed by GitHub
parent 057efbfe95
commit 555be63c90
3 changed files with 104 additions and 81 deletions
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36
contracts/utils/cryptography/ECDSA.sol
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@ -24,23 +24,35 @@ library ECDSA {
* be too long), and then calling {toEthSignedMessageHash} on it.
*/
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
// Check the signature length
if (signature.length != 65) {
revert("ECDSA: invalid signature length");
}
// Divide the signature in r, s and v variables
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
// solhint-disable-next-line no-inline-assembly
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
// Check the signature length
// - case 65: r,s,v signature (standard)
// - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098)
if (signature.length == 65) {
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
// solhint-disable-next-line no-inline-assembly
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
} else if (signature.length == 64) {
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
// solhint-disable-next-line no-inline-assembly
assembly {
let vs := mload(add(signature, 0x40))
r := mload(add(signature, 0x20))
s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
v := add(shr(255, vs), 27)
}
} else {
revert("ECDSA: invalid signature length");
}
return recover(hash, v, r, s);