Direct Verification of Ed25519 Signatures in a Solana Contract
As blockchain developers, we are often challenged to integrate different signing mechanisms into our contracts. One such mechanism is ed25519, which allows for secure and efficient digital signatures using a cryptographic hash function and a private key. While there are solutions that allow for indirect verification of ed25519 signatures, placing the signature statement and the call statement in a single transaction can be cumbersome.
In this article, we explore an alternative approach to directly verifying ed25519 signatures in a Solana contract.
The Problem
Before we get into the solution, let’s look at some common problems:
- Transaction Size: Direct verification of ed25519 signatures requires a significant amount of storage space. By putting the signature statement and the call statement in a single transaction, we risk exceeding the maximum transaction size limit.
- Performance overhead: Verifying each individual signature can introduce additional delays that may be unacceptable for high-frequency trading or real-time applications.
The Solution
To address these concerns, we implement a custom solution that uses the verify directive to directly verify ed25519 signatures. This approach requires careful consideration of the following aspects:
Signature verification function
We create a special function in our contract that verifies ed25519 signatures. This function takes the input of the signature and the hash of the contract repository as arguments.
pragma solidity ^0.8.0;
Contract SignatureVerifier {
// ... (other variables)
function verifyEd25519Signature(
bytes32 _signature,
address _from,
bytes_storage_Hash,
uint256 _gasLimit
) public view return (bool) {
// Verify the signature with ed25519
require ed25519Verify(_signature, _from, _storageHash, _gasLimit);
return true;
}
}
ed25519 library integration
We will use the `solana-verify'' library to perform the actual verification. This library provides a high-level interface for verifying signatures with ed25519.
pragma solidity ^0.8.0;
library solanaVerify {
function verify(uint256 _hash) internal view returns (bool);
}
Contract SignatureVerifier {
using solanaVerify.sol(solanaVerify);
// ... (other variables)
function verifyEd25519Signature(
bytes32 _signature,
address _from,
bytes_storageHash
) public view returns (bool) {
return verify(_signature, _from, _storageHash);
}
}
Transaction Structure
To avoid exceeding the maximum transaction size limit, we structure our contract as follows:
pragma solidity ^0.8.0;
Contract SignatureVerifier {
// ... (other variables)
bytes32 public signature;
Address to the public from;
bytes storage storageHash;
function setSignature(bytes32 _signature) public {
requirement ed25519Verify(_signature, from, storageHash, 100000); // 100k gas
signature = _signature;
from = address(...);
storageHash = _storageHash;
}
function verifyEd25519Signature(
bytes32 _signature,
address _from,
bytes storage _storageHash
) public view return (bool) {
requirement ed25519Verify(_signature, _from, _storageHash, 100000); // 100k gas
return true;
}
}
Example Usage
To use this solution, create a new contract and import the SignatureVerifier contract.
“salt
pragma solidity ^0.8.