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

Creates and 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.

// Use the following ECC key loaded from JWK format.
$sbJwk = new CkStringBuilder();
$sbJwk->Append('{\'kty\':\'EC\',');
$sbJwk->Append('\'crv\':\'P-256\',');
$sbJwk->Append('\'x\':\'f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\',');
$sbJwk->Append('\'y\':\'x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\',');
$sbJwk->Append('\'d\':\'jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI\'');
$sbJwk->Append('}');

$eccKey = new CkPrivateKey();
// Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
// into the private key object. (See the online reference documentation..)
$success = $eccKey->LoadJwk($sbJwk->getAsString());
if ($success != true) {
    print $eccKey->lastErrorText() . "\n";
    exit;
}

// Create the JWS Protected Header
$jwsProtHdr = new CkJsonObject();
$jwsProtHdr->AppendString('alg','ES256');

$jws = new CkJws();

// Set the protected header:
$signatureIndex = 0;
$jws->SetProtectedHeader($signatureIndex,$jwsProtHdr);

// Set the ECC key:
$jws->SetPrivateKey($signatureIndex,$eccKey);

// Set the payload.
$bIncludeBom = false;
$payloadStr = 'In our village, folks say God crumbles up the old moon into stars.';
$jws->SetPayload($payloadStr,'utf-8',$bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
$jwsCompact = $jws->createJws();
if ($jws->get_LastMethodSuccess() != true) {
    print $jws->lastErrorText() . "\n";
    exit;
}

print 'JWS: ' . $jwsCompact . "\n";

// Note: ECC signatures use random values, so the output will be different each time a signature is produced.
// sample output:
// JWS: eyJhbGciOiJFUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.J6EGTNkeuEjehHHBu0SOKzifm8r35wbx49A5964pxzB7gannyZZPMkK7vmlaPJ-K8Xmm8cZsQySAPC12Xd8avw

// Now load the JWS, validate, and recover the original text.
$jws2 = new CkJws();

// Load the JWS.
$success = $jws2->LoadJws($jwsCompact);

// eccPubKey is a CkPublicKey
$eccPubKey = $eccKey->GetPublicKey();

// Set the ECC public key used for validation.
$signatureIndex = 0;
$jws2->SetPublicKey($signatureIndex,$eccPubKey);

// Validate the 1st (and only) signature at index 0..
$v = $jws2->Validate($signatureIndex);
if ($v < 0) {
    // Perhaps Chilkat was not unlocked or the trial expired..
    print 'Method call failed for some other reason.' . "\n";
    print $jws2->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";

// Recover the original content:
print $jws2->getPayload('utf-8') . "\n";

// Examine the protected header:
// joseHeader is a CkJsonObject
$joseHeader = $jws2->GetProtectedHeader($signatureIndex);
if ($jws2->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.
// In our village, folks say God crumbles up the old moon into stars.
// Protected (JOSE) header:
// { 
//   "alg": "ES256"
// }

?>