Date of Award

6-3-2004

Document Type

Thesis (Master's)

Department

Department of Computer Science

First Advisor

Sean Smith

Abstract

Dartmouth's Greenpass project seeks to provide strong access control to a wireless network while simultaneously providing flexible guest access; to do so, it augments the Wi-Fi Alliance's existing WPA standard, which offers sufficiently strong user authentication and access control, with authorization based on SPKI certificates. SPKI allows certain local users to delegate network access to guests by issuing certificates that state, in essence, "he should get access because I said it's okay." The Greenpass RADIUS server described in Kim's thesis [55] performs an authorization check based on such statements so that guests can obtain network access without requiring a busy network administrator to set up new accounts in a centralized database. To our knowledge, Greenpass is the first working delegation-based solution to Wi-Fi access control. My thesis describes the Greenpass client tools, which allow a guest to introduce himself to a delegator and allow the delegator to issue a new SPKI certificate to the guest. The guest does not need custom client software to introduce himself or to connect to the Wi-Fi network. The guest and delegator communicate using a set of Web applications. The guest obtains a temporary key pair and X.509 certificate if needed, then sends his public key value to a Web server we provide. The delegator looks up her guest's public key and runs a Java applet that lets her verify her guests' identity using visual hashing and issue a new SPKI certificate to him. The guest's new certificate chain is stored as an HTTP cookie to enable him to "push" it to an authorization server at a later time. I also describe how Greenpass can be extended to control access to a virtual private network (VPN) and suggest several interesting future research and development directions that could build on this work.My thesis describes the Greenpass client tools, which allow a guest to introduce himself to a delegator and allow the delegator to issue a new SPKI certificate to the guest. The guest does not need custom client software to introduce himself or to connect to the Wi-Fi network. The guest and delegator communicate using a set of Web applications. The guest obtains a temporary key pair and X.509 certificate if needed, then sends his public key value to a Web server we provide. The delegator looks up her guest's public key and runs a Java applet that lets her verify her guests' identity using visual hashing and issue a new SPKI certificate to him. The guest's new certificate chain is stored as an HTTP cookie to enable him to "push" it to an authorization server at a later time. I also describe how Greenpass can be extended to control access to a virtual private network (VPN) and suggest several interesting future research and development directions that could build on this work.

Comments

Originally posted in the Dartmouth College Computer Science Technical Report Series, number TR2004-509.

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