amazon web services - Verify JWT signature with RSA public key in PHP

Solution:

Could you try using another PHP library: https://github.com/Spomky-Labs/jose

// File test.php
require_once __DIR__.'/vendor/autoload.php';

use Jose\Checker\ExpirationChecker;
use Jose\Checker\IssuedAtChecker;
use Jose\Checker\NotBeforeChecker;
use Jose\Factory\KeyFactory;
use Jose\Factory\LoaderFactory;
use Jose\Factory\VerifierFactory;
use Jose\Object\JWKSet;
use Jose\Object\JWSInterface;

// We create a JWT loader.
$loader = LoaderFactory::createLoader();

// We load the input
$jwt = $loader->load($input);

if (!$jws instanceof JWSInterface) {
    die('Not a JWS');
}

// Please note that at this moment the signature and the claims are not verified

// To verify a JWS, we need a JWKSet that contains public keys (from RSA key in your case).
// We create our key object (JWK) using a RSA public key
$jwk = KeyFactory::createFromPEM('-----BEGIN RSA PUBLIC KEY-----...');

// Then we set this key in a keyset (JWKSet object)
// Be careful, the JWKSet object is immutable. When you add a key, you get a new JWKSet object.
$jwkset = new JWKSet();
$jwkset = $jwkset->addKey($jwk);


// We create our verifier object with a list of authorized signature algorithms (only 'RS512' in this example)
// We add some checkers. These checkers will verify claims or headers.
$verifier = VerifierFactory::createVerifier(
    ['RS512'],
    [
        new IssuedAtChecker(),
        new NotBeforeChecker(),
        new ExpirationChecker(),
    ]
);

$is_valid = $verifier->verify($jws, $jwkset);

// The variable $is_valid contains a boolean that indicates the signature is valid or not.
// If a claim is not verified (e.g. the JWT expired), an exception is thrown.

//Now you can use the $jws object to retreive all claims or header key/value pairs
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Solution:

I was able to get this library to work. However I had to build the key using KeyFactory::createFromValues instead of KeyFactory::createFromPEM. THANK YOU!