(PHP Extension) Validate a JWS Using ECDSA P-256 SHA-256

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

Note: This example requires Chilkat v9.5.0.66 or greater.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

// Note: This example requires Chilkat v9.5.0.66 or greater.

// 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 CkStringBuilder();
$sbPubKey->Append('{\'kty\':\'EC\',');
$sbPubKey->Append('\'crv\':\'P-256\',');
$sbPubKey->Append('\'x\':\'f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\',');
$sbPubKey->Append('\'y\':\'x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\'');
$sbPubKey->Append('}');

$pubKey = new CkPublicKey();
$success = $pubKey->LoadFromString($sbPubKey->getAsString());
if ($success != true) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

$jws = new CkJws();

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

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

$success = $jws->LoadJwsSb($sbJws);
if ($success != true) {
    print $jws->lastErrorText() . "\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..
    print 'Method call failed for some other reason.' . "\n";
    print $jws->lastErrorText() . "\n";
    exit;
}

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

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

// Recover the original content:
print 'Recovered content:' . "\n";
print $jws->getPayload('utf-8') . "\n";
print '--' . "\n";

// Examine the protected header:
// joseHeader is a CkJsonObject
$joseHeader = $jws->GetProtectedHeader($signatureIndex);
if ($jws->get_LastMethodSuccess() != true) {
    print 'No protected header found at the given index.' . "\n";
    exit;
}

$joseHeader->put_EmitCompact(false);

print 'Protected (JOSE) header:' . "\n";
print $joseHeader->emit() . "\n";

// Output:

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

?>