PHP Requires Chilkat v11.0.0+

Validate a JWS Using ECDSA P-256 SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256 Chilkat2 PHP

<?php

use Chilkat2\JsonObject;
use Chilkat2\Jws;
use Chilkat2\PublicKey;
use Chilkat2\StringBuilder;

// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example takes a JSON signature in compact serialization format,
// and uses an ECDSA public key to validate and recover the protected header and payload.

// We only need a public key for signature validation.  This is the ECDSA public key
// that is used:

//      {"kty":"EC",
//       "crv":"P-256",
//       "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
//       "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"
//      }

$sbPubKey = new StringBuilder();
$sbPubKey->Append('{"kty":"EC",');
$sbPubKey->Append('"crv":"P-256",');
$sbPubKey->Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",');
$sbPubKey->Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"');
$sbPubKey->Append('}');

$pubKey = new PublicKey();
try {
    $pubKey->LoadFromString($sbPubKey->GetAsString());

    $jws = new Jws();

    // Set the ECC public key:
    $signatureIndex = 0;
    $jws->SetPublicKey($signatureIndex, $pubKey);

    // Load the JWS.
    $sbJws = new StringBuilder();
    $sbJws->Append('eyJhbGciOiJFUzI1NiJ9');
    $sbJws->Append('.');
    $sbJws->Append('eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt');
    $sbJws->Append('cGxlLmNvbS9pc19yb290Ijp0cnVlfQ');
    $sbJws->Append('.');
    $sbJws->Append('DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA');
    $sbJws->Append('pmWQxfKTUJqPP3-Kg6NU1Q');

    $jws->LoadJwsSb($sbJws);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// Validate the 1st (and only) signature at index 0..
$v = $jws->Validate($signatureIndex);
if ($v < 0) {
    // Perhaps Chilkat was not unlocked or the trial expired..
    echo "Method call failed for some other reason.\n";
    echo $jws->LastErrorText, "\n";
    exit;
}

if ($v == 0) {
    echo "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both.\n";
    exit;
}

// If we get here, the signature was validated..
echo "Signature validated.\n";
echo "--\n";

// Recover the original content:
echo "Recovered content:\n";
echo $jws->GetPayload('utf-8'), "\n";
echo "--\n";

// Examine the protected header:

$joseHeader = new JsonObject();
try {
    $jws->GetProtectedH($signatureIndex, $joseHeader);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

$joseHeader->EmitCompact = false;

echo "Protected (JOSE) header:\n";
echo $joseHeader->Emit(), "\n";

// Output:

//     Signature validated.
//     --
//     Recovered content:
//     {"iss":"joe",
//      "exp":1300819380,
//      "http://example.com/is_root":true}
//     --
//     Protected (JOSE) header:
//     {
//       "alg": "ES256"
//     }