╭╯ ECDSA384

Introduction

This library provides functionality for ECDSA verification over any 384-bit curve. Currently, this is the most efficient implementation out there, consuming ~8.9 million gas per call.

The approach is Strauss-Shamir double scalar multiplication with 6 bits of precompute + affine coordinates. For reference, naive implementation uses ~400 billion gas, which is 50000 times more expensive.

We also tried using projective coordinates, however, the gas consumption rose to ~9 million gas.

Functions

To use the ECDSA384 library, you need to import it.

import "@solarity/solidity-lib/libs/crypto/ECDSA384.sol";

And optionally bind it to the type with the using statement.

using ECDSA384 for *;

verify

function verify(
    ECDSA384.Parameters memory curveParams_,
    bytes memory hashedMessage_,
    bytes memory signature_,
    bytes memory pubKey_
) internal view returns (bool);

Description

The function to verify the ECDSA signature.

Parameters:

Name	Type	Description
curveParams	struct ECDSA384.Parameters	The 384-bit curve parameters
hashedMessage	bytes	The already hashed message to be verified
signature	bytes	The ECDSA signature. Equals to bytes(r) + bytes(s)
pubKey	bytes	The full public key of a signer. Equals to bytes(x) + bytes(y). Note that signatures only from the lower part of the curve are accepted. If your s > n / 2, change it to s = n - s

Example

function verifySECP384r1(
    bytes calldata message_,
    bytes calldata signature_,
    bytes calldata pubKey_
) external view returns (bool) {
    ECDSA384.Parameters memory curveParams_ = ECDSA384.Parameters({
        a: hex"fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffff0000000000000000fffffffc",
        b: hex"b3312fa7e23ee7e4988e056be3f82d19181d9c6efe8141120314088f5013875ac656398d8a2ed19d2a85c8edd3ec2aef",
        gx: hex"aa87ca22be8b05378eb1c71ef320ad746e1d3b628ba79b9859f741e082542a385502f25dbf55296c3a545e3872760ab7",
        gy: hex"3617de4a96262c6f5d9e98bf9292dc29f8f41dbd289a147ce9da3113b5f0b8c00a60b1ce1d7e819d7a431d7c90ea0e5f",
        p: hex"fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffff0000000000000000ffffffff",
        n: hex"ffffffffffffffffffffffffffffffffffffffffffffffffc7634d81f4372ddf581a0db248b0a77aecec196accc52973"
    });

    return curveParams_.verify(abi.encodePacked(sha256(message_)), signature_, pubKey_);
}