A Generalized Framework for Kerberos Pre-Authentication

Abstract

Kerberos is a protocol for verifying the identity of principals (e.g., a workstation user or a network server) on an open network. The Kerberos protocol provides a facility called pre-authentication. Pre-authentication mechanisms can use this facility to extend the Kerberos protocol and prove the identity of a principal.

This document describes a more formal model for this facility. The model describes what state in the Kerberos request a pre-authentication mechanism is likely to change. It also describes how multiple pre-authentication mechanisms used in the same request will interact.

This document also provides common tools needed by multiple pre-authentication mechanisms. One of these tools is a secure channel between the client and the key distribution center with a reply key strengthening mechanism; this secure channel can be used to protect the authentication exchange and thus eliminate offline dictionary attacks. With these tools, it is relatively straightforward to chain multiple authentication mechanisms, utilize a different key management system, or support a new key agreement algorithm. [STANDARDS-TRACK]

Abstract as published in the RFC, via rfc-editor.org.

What “Proposed Standard” means

An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.