(PHP Extension) Verify JWT Using HS256, HS384, or HS512

Demonstrates how to verify a JWT that was signed using HS256, HS384, or HS512. (HS256 is JWT's acronym for HMAC-SHA256.)

This example verifies the signature. It also does the following:

• Checks to see if the time constraints ("nbf" and "exp") are valid.
• Recovers the original JOSE header.
• Recovers the original claims JSON.

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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");

// Demonstrates how to verify an HMAC JWT using a shared secret (password).

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

$jwt = new CkJwt();

$token = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU';

// First verify the signature.
// The password used to create this JWT was "secret".
$sigVerified = $jwt->VerifyJwt($token,'secret');
print 'with correct password: ' . $sigVerified . "\n";

// Now try with a different password:
$sigVerified = $jwt->VerifyJwt($token,'secret2');
print 'with incorrect password ' . $sigVerified . "\n";

// Let's see if the time constraints, if any, are valid.
// The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
// If the current system time is before the "nbf" time, or after the "exp" time,
// then IsTimeValid will return false/0.
// Also, we'll allow a leeway of 60 seconds to account for any clock skew.
// Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
$leeway = 60;
$bTimeValid = $jwt->IsTimeValid($token,$leeway);
print 'time constraints valid: ' . $bTimeValid . "\n";

// Now let's recover the original claims JSON (the payload).
$payload = $jwt->getPayload($token);
// The payload will likely be in compact form:
print $payload . "\n";

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
$json = new CkJsonObject();
$success = $json->Load($payload);
$json->put_EmitCompact(false);
print $json->emit() . "\n";

// We can recover the original JOSE header in the same way:
$joseHeader = $jwt->getHeader($token);
// The payload will likely be in compact form:
print $joseHeader . "\n";

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
$success = $json->Load($joseHeader);
$json->put_EmitCompact(false);
print $json->emit() . "\n";

?>