(PHP Extension) Validate JWS with Multiple Signatures using the General JSON Serialization Format

Validates and recovers data and headers from a JSON Web Signature (JWS) containing 3 signatures.

Note: Chilkat supports all of the following JWS algorithms:

   +--------------+-------------------------------+--------------------+
   | "alg" Param  | Digital Signature or MAC      | Implementation     |
   | Value        | Algorithm                     | Requirements       |
   +--------------+-------------------------------+--------------------+
   | HS256        | HMAC using SHA-256            | Required           |
   | HS384        | HMAC using SHA-384            | Optional           |
   | HS512        | HMAC using SHA-512            | Optional           |
   | RS256        | RSASSA-PKCS1-v1_5 using       | Recommended        |
   |              | SHA-256                       |                    |
   | RS384        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-384                       |                    |
   | RS512        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-512                       |                    |
   | ES256        | ECDSA using P-256 and SHA-256 | Recommended+       |
   | ES384        | ECDSA using P-384 and SHA-384 | Optional           |
   | ES512        | ECDSA using P-521 and SHA-512 | Optional           |
   | PS256        | RSASSA-PSS using SHA-256 and  | Optional           |
   |              | MGF1 with SHA-256             |                    |
   | PS384        | RSASSA-PSS using SHA-384 and  | Optional           |
   |              | MGF1 with SHA-384             |                    |
   | PS512        | RSASSA-PSS using SHA-512 and  | Optional           |
   |              | MGF1 with SHA-512             |                    |
   +--------------+-------------------------------+--------------------+

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.

// First, prepare the public keys that will be needed for each signature.

// ---------------------------------------------------
// Use the following RSA key loaded from JWK format.
$sbRsaJwk = new CkStringBuilder();
$sbRsaJwk->Append('{\'kty\':\'RSA\',');
$sbRsaJwk->Append('\'n\':\'ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx');
$sbRsaJwk->Append('HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs');
$sbRsaJwk->Append('D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH');
$sbRsaJwk->Append('SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV');
$sbRsaJwk->Append('MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8');
$sbRsaJwk->Append('NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ\',');
$sbRsaJwk->Append('\'e\':\'AQAB\'');
$sbRsaJwk->Append('}');

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

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

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

// ---------------------------------------------------
// The HMAC key (in base64url format)
$hmacKey = 'AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow';

// The code below will verify each of the signatures in this JWS:

// { 
//   "payload": "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu",
//   "signatures": [
//     { 
//       "protected": "eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0",
//       "signature": "IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw"
//     },
//     { 
//       "protected": "eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ",
//       "signature": "1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw"
//     },
//     { 
//       "protected": "eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0",
//       "signature": "YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw"
//     }
//   ]
// }

$sbJws = new CkStringBuilder();
$sbJws->Append('{ ');
$sbJws->Append('  \'payload\': \'SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu\',');
$sbJws->Append('  \'signatures\': [');
$sbJws->Append('    { ');
$sbJws->Append('      \'protected\': \'eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0\',');
$sbJws->Append('      \'signature\': \'IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw\'');
$sbJws->Append('    },');
$sbJws->Append('    { ');
$sbJws->Append('      \'protected\': \'eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ\',');
$sbJws->Append('      \'signature\': \'1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw\'');
$sbJws->Append('    },');
$sbJws->Append('    { ');
$sbJws->Append('      \'protected\': \'eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0\',');
$sbJws->Append('      \'signature\': \'YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw\'');
$sbJws->Append('    }');
$sbJws->Append('  ]');
$sbJws->Append('}');

$jws = new CkJws();

$success = $jws->LoadJwsSb($sbJws);
if ($success != true) {
    print $jws->lastErrorText() . "\n";
    exit;
}

// The payload is easily accessible:
print 'Payload: ' . $jws->getPayload('utf-8') . "\n";

$sbKeyId = new CkStringBuilder();
$bCaseSensitive = false;

$numSignatures = $jws->get_NumSignatures();
$i = 0;
while ($i < $numSignatures) {
    // protHeader is a CkJsonObject
    $protHeader = $jws->GetProtectedHeader($i);

    print '--------------------------' . "\n";
    print $i . ': ' . "\n";

    // Get the protected header.
    $protHeader->put_EmitCompact(false);
    print $protHeader->emit() . "\n";

    // Get the key ID ("kid") member.

    // Note: In this example, the "kid" values are contained in the protected headers.
    // They could've just as easily been located in unprotected headers.  In that case,
    // we would've called GetUnprotectedHeader(i) instead of GetProtectedHeader(i).

    $sbKeyId->Clear();
    $sbKeyId->Append($protHeader->stringOf('kid'));

    // Set the key based on key ID.
    if ($sbKeyId->ContentsEqual('myRsaKey',$bCaseSensitive) == true) {
        $jws->SetPublicKey($i,$rsaKey);
    }

    if ($sbKeyId->ContentsEqual('myEcKey',$bCaseSensitive) == true) {
        $jws->SetPublicKey($i,$eccKey);
    }

    if ($sbKeyId->ContentsEqual('myMacKey',$bCaseSensitive) == true) {
        $jws->SetMacKey($i,$hmacKey,'base64url');
    }

    // Validate this signature.
    $v = $jws->Validate($i);
    if ($v < 0) {
        // Perhaps Chilkat was not unlocked or the trial expired..
        print 'Validate failed for some other reason.' . "\n";
        print $jws->lastErrorText() . "\n";
    }
    else {
        if ($v == 0) {
            print 'Invalid signature.  The key was incorrect, the JWS was invalid, or both.' . "\n";
        }
        else {
            print 'Signature validated.' . "\n";
        }

    }

    $i = $i + 1;
}

// The output of this program is:

// 	Payload: In our village, folks say God crumbles up the old moon into stars.
// 	--------------------------
// 	0: 
// 	{
// 	  "alg": "RS256",
// 	  "kid": "myRsaKey"
// 	}
// 
// 	Signature validated.
// 	--------------------------
// 	1: 
// 	{
// 	  "alg": "ES256",
// 	  "kid": "myEcKey"
// 	}
// 
// 	Signature validated.
// 	--------------------------
// 	2: 
// 	{
// 	  "alg": "HS256",
// 	  "kid": "myMacKey"
// 	}
// 
// 	Signature validated.

?>