Reducing the Dependence of SPKI/SDSI on PKI
Trust-management systems address the authorization problem in
distributed systems. They offer several advantages over other
approaches, such as support for delegation and making authorization
decisions in a decentralized manner. Nonetheless, trust-management
systems such as KeyNote and SPKI/SDSI have seen limited deployment in
the real world. One reason for this is that both systems require a
public-key infrastructure (PKI) for authentication, and PKI has proven
difficult to deploy, because each user is required to manage his/her
own private/public key pair. The key insight of our work is that
issuance of certificates in trust-management systems, a task that
usually requires public-key cryptography, can be achieved using
secret-key cryptography as well. We demonstrate this concept by
showing how SPKI/SDSI can be modified to use Kerberos, a secret-key
based authentication system, to issue SPKI/SDSI certificates. The
resulting trustmanagement system retains all the capabilities of
SPKI/SDSI, but is much easier to use because a public key is only
required for each SPKI/SDSI server, but no longer for every
user. Moreover, because Kerberos is already well established, our
approach makes SPKI/SDSI-based trust management systems easier to
deploy in the real world.
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Somesh Jha
Last modified: Tue Sep 11 13:59:48 CDT 2007