A Laravel Auth Provider to create a Web3 Public key auth system.

Web3PubKeyAuthProvider

<?php

namespace App\Providers\Web3PubKey;

use App\Models\User;
use Illuminate\Contracts\Auth\Authenticatable;
use Illuminate\Contracts\Auth\UserProvider;
use SodiumException;
use Tighten\SolanaPhpSdk\Exceptions\InputValidationException;
use Tighten\SolanaPhpSdk\Util\Buffer;
use function Sodium\crypto_sign_verify_detached;

class Web3PubKeyAuthProvider implements UserProvider
{
    public function __construct(private readonly User $model)
    {
    }

    public static function getSignatureMessage(string $publicKey): string
    {
        return trans('Signing this message, I confirm that I am owner of :key', ['key' => $publicKey]);
    }

    public function retrieveById($identifier): Authenticatable|null
    {
        /** @phpstan-ignore-next-line */
        return $this->model->find($identifier);
    }

    public function retrieveByToken($identifier, $token)
    {
        //no remember token
    }

    public function updateRememberToken(Authenticatable $user, $token): void
    {
        //no remember token
    }

    public function retrieveByCredentials(array $credentials): Authenticatable|null
    {
        return $this->model->where('auth_token', $credentials['public_key'])->first();
    }

    /**
     * @throws InputValidationException
     * @throws SodiumException
     */
    public function validateCredentials(Authenticatable $user, array $credentials): bool
    {
        if (!array_key_exists('public_key', $credentials) ||
            !array_key_exists('signature', $credentials)
        ) {
            return false;
        }

        return $this->validateSignature($credentials['public_key'], $credentials['signature']);
    }

    /**
     * @throws InputValidationException
     * @throws SodiumException
     */
    private function validateSignature(string $publicKey, array $signature): bool
    {
        $signatureBuffer = new Buffer($signature);
        $message = self::getSignatureMessage($publicKey);
        $publicKeyBuffer = Buffer::fromBase58($publicKey);

        return crypto_sign_verify_detached($signatureBuffer->toString(), $message, $publicKeyBuffer->toString());
    }
}