Data Signer

This library provides a logic for digital signing and validating of a binary data.

Inputs and outputs are binary data, don't be afraid to use the petrknap/binary.

Implementations

• Edwards-curve Digital Signature Algorithm (Ed25519)
• Hash-based Message Authentication Code (HMAC)
• Sodium (Ed25519)

Usage

The basic use of a Data Signer interface is quite simple:

use PetrKnap\DataSigner\Some;

$signer = new Some\DataSigner();
$data = 'some data';
$signature = $signer->sign($data);
if ($signer->verify($data, $signature)) {
    echo 'Data was successfully verified by signature.';
}

Domain-specific signing

If you need to limit the validity of the signature to a specific purpose (domain), just set it to the Data Signer service:

use PetrKnap\DataSigner\Some;

$signer = new Some\DataSigner();
$data = 'some data';
$signature = $signer->withDomain('password_reset')->sign($data);
if (!$signer->withDomain('cookies')->verify($data, $signature)) {
    echo 'You can not use signature generated for `password_reset` in `cookies`.';
}

Time-limited signing

If you need to limit the validity of the signature to specific time (expiration), just give it to the Data Signer's method sign:

use PetrKnap\DataSigner\Some;

$signer = new Some\DataSigner();
$data = 'some data';
$signature = $signer->sign($data, expiresAt: new DateTimeImmutable('2025-04-05 09:40:53+02:00'));
if (!$signer->verify($data, $signature)) {
    echo 'You can not use signature after its expiration.';
}

Signable data transfer object

If you communicate through data transfer objects, you can use a Signable Data interface:

use PetrKnap\DataSigner\Some;

$apiClient = new class (new Some\DataSigner()) {
    public function __construct(private readonly Some\DataSigner $dataSigner) {}
    public function put(Some\DataTransferObject $payload): void {
        $request = [
            'payload' => $payload,
            'signature' => (string) $this->dataSigner->sign($payload)->encode()->base64(),
        ];
        echo json_encode($request);  # here should be the API call
    }
};
$apiClient->put(new Some\DataTransferObject(
    property: 'some value',
));

Communication trough 3rd party machine

If you need to sign data forwarded trough 3rd party machine (f.e. by token or cookie), you can use the Signature with data:

use PetrKnap\Binary\Binary;
use PetrKnap\DataSigner\Some;

$signer = new Some\DataSigner();

$passwordResetToken = (string) $signer->withDomain('password_reset')->sign(
    data: 'some_user',
    expiresAt: (new DateTimeImmutable())->modify('+3 hours'),
)->encode(withData: true)->zlib()->base64(urlSafe: true);

$verifiedUserIdentifier = $signer->withDomain('password_reset')->verified(
    (string) Binary::decode($passwordResetToken)->base64()->zlib(),
)->orElseThrow();
echo "Verified user identifier is `{$verifiedUserIdentifier}`.";

WARNING: The data are only signed (readable), use the petrknap/crypto-sodium if you need to encrypt them.

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Run composer require petrknap/data-signer to install it. You can support this project via donation. The project is licensed under the terms of the LGPL-3.0-or-later.