Digestauthenticated

Digestauthenticated refers to the HTTP Digest Access Authentication scheme, a challenge-response method used to verify a client's identity without sending a plaintext password over the network. While commonly called Digest authentication, the term Digestauthenticated may appear in contexts discussing its use or implementation. The approach relies on cryptographic hashes and a server-generated nonce to protect credentials and deter replay attacks.

How it works in brief: when a client requests a protected resource, the server responds with a 401 Unauthorized status and a WWW-Authenticate header that includes a realm, a nonce, and potentially an algorithm and quality-of-protection (qop) values. The client then prompts the user for credentials and sends an Authorization header containing a hash-based response. The response is computed from values such as HA1 (a hash of username, realm, and password), the nonce, a client nonce (cnonce), the nonce-count, the chosen qop, and HA2 (a hash of the method and the requested URI). The server performs the same calculations to verify the response. This mechanism avoids sending the actual password, using the nonce to help prevent replay.

Standards and variants: Digest authentication was standardized in RFC 2069 and later refined in RFC 2617, with updates in RFC 7616 and RFC 7617. Algorithms such as MD5 and MD5-sess are supported, and qop values like auth or auth-int can be used to offer integrity protection for the request. Opaque values and stale indicators may accompany challenges to aid state management.

Security and limitations: Digestauthenticated improves over plaintext password transmission but relies on MD5, which has known weaknesses. It also requires TLS for overall confidentiality and is vulnerable to offline attacks if password strength is poor. Modern systems often prefer TLS with more modern schemes, though Digest authentication remains supported in many servers and clients for backward compatibility.