As well as the signed tokens, the encrypted tokens also have unprotected header. But with one difference: there are two unprotected headers:
Shared unprotected header applicable to all recipients.
Per-recipient unprotected header.
With the example below, we will create an encrypted token for two recipient and some unprotected header parameters:
$jwe = $jweBuilder->create()->withPayload('...')->withSharedProtectedHeader(['enc' => 'A256GCM', 'alg' => 'A256KW'])->withSharedHeader(['author' => 'John Doe'])->addRecipient($recipient_public_key_1, ['message' => 'Hello World!'])->addRecipient($recipient_public_key_2, ['description' => 'Nice song for you'])->build();
$jwe will be a valid JWE object built for two recipients. The unprotected header parameter
author is applicable to the whole token while
description are available only for the first and second recipient respectively.
Note: when an unprotected header is set, the Compact Serialization mode is not available.