Digest Access Authentication is a way for service providers to verify a person’s credentials by using a web browser.
Specifically, digest access authentication uses the HTTP protocol, applying MD5 cryptographic hashing and a nonce value to prevent replay attacks. Hash values are affixed to the person’s username and password before they are sent over the network, enabling the provider’s server to authenticate the person.
Digest access authentication is preferred over basic access authentication, which uses unsecure Base64 encoding over HTTP. Basic access authentication is unsecure unless combined with transport-layer security (TLS).
“Digest Access Authentication provides for the hashing of usernames and passwords so online services can verify that the person accessing their service on the web browser is who they say they are.”