Bridging the Usability Gap of PKI

Tobias Straub

tstraub@gkec.tu-darmstadt.de
Computer Science Department
Technische Universitaet Darmstadt

From a user's viewpoint, security in general and PKI (public key infrastructure) in particular are complex matters. According to a recent study [kes04], the majority of security incidents still can be traced back to user errors or carelessness, although users' troubles with PKI-enabled applications are known since the study of Whitten and Tygar investigating the handling of secure e-mail [WT99].

Unfortunately, due to the nature of PKI, user interaction cannot be avoided entirely, e.g. when an unknown certificate has to be imported as a trust anchor. In my work, I am proposing several measures to face the usability challenges of PKI.

One of them is a generic framework to comprehensively evaluate usability and utility of PKI-enabled applications [SB04]. Apart from being a tool to detect usability problems and assess applications, it may as well serve as a requirements specification for application designers.

Another idea is to delegate complex and security-critical tasks to skilled personnel or a service provider. For instance, the protocol described in [Str04] allows an organization to outsource the task of maintaining a PKI in a way that it retains full control and does not have to trust the service provider.

References

kes04
Lagebericht zur Informationssicherheit.
In: kes 4/2004 and 5/2004.

Str04
T. Straub.
A Method for Strengthening Certificate Enrollment.
WartaCrypt, 2004.

SB04
T. Straub and H. Baier.
A Framework for Evaluating the Usability and the Usefulness of PKI-enabled Applications.
European PKIWorkshop, 2004. (Springer LNCS 3093)

WT99
A. Whitten, J.D. Tygar.
Why Johnny Can't Encrpyt: A Usability Evaluation of PGP 5.0.
USENIX Security Symposium, 1999.