<?php
use Jose\Component\Encryption\Algorithm\KeyEncryption\RSAOAEP256;
use Jose\Component\Encryption\Algorithm\ContentEncryption\A256CBCHS512;
use Jose\Component\Encryption\JWEBuilder;
use Jose\Component\Encryption\Serializer\CompactSerializer;
use Jose\Component\Core\JWK;

// Load the PGW's Encryption Public Key
$pgwEncryptionPublicKey = file_get_contents('key/PACOEncryptionPublic.txt');

// JSON Payload to be encrypted
$payload = [
    'amount' => '100.00',
    'currency' => 'USD',
    'customer_id' => '12345',
];

// Create a JWK instance for key encryption
$keyEncryptionKey = JWK::createFromKey($pgwEncryptionPublicKey, null, ['alg' => 'RSA-OAEP-256', 'use' => 'enc']);

// Build the JWE token
$jweBuilder = new JWEBuilder();
$jwe = $jweBuilder
    ->create() // Create an empty JWE token
    ->withPayload(json_encode($payload)) // Set the JSON payload
    ->withEncryptionKey($keyEncryptionKey) // Set the encryption key
    ->addRecipient($keyEncryptionKey) // Add recipient for key encryption
    ->withHeader('alg', 'RSA-OAEP-256') // Specify key encryption algorithm
    ->withHeader('enc', 'A256CBC-HS512') // Specify content encryption algorithm
    ->build(); // Build the JWE token

// Serialize the JWE token
$jweSerializer = new CompactSerializer();
$serializedJwe = $jweSerializer->serialize($jwe);

// Attach the encrypted payload to your API request and send it to 2C2P Payment Gateway
// ...
?>