Configuration settings: 'accept_schemes' => 'basic'|'digest'|'basic digest' 'realm' => <string> 'digest_domains' => <string> Space-delimited list of URIs 'nonce_timeout' => <int> 'use_opaque' => <bool> Whether to send the opaque value in the header 'algorithm' => <string> See $supportedAlgos. Default: MD5 'proxy_auth' => <bool> Whether to do authentication as a Proxy