Paper 2007/234 Original: eprint.iacr.org/2007/234 ↗

Provable-Security Analysis of Authenticated Encryption in Kerberos

Abstract

Kerberos is a widely deployed network authentication protocol currently being considered for standardization. Many works have analyzed its security, identifying flaws and often suggesting fixes, thus promoting the protocol's evolution. Several recent results present successful, formal methods-based verifications of a significant portion of the current version, v.5, and some even imply security in the computational setting. For these results to hold, encryption in Kerberos should satisfy strong cryptographic security notions. However, prior to our work, none of the encryption schemes currently deployed as part of Kerberos, nor their proposed revisions, were known to provably satisfy such notions. We take a close look at Kerberos' encryption, and we confirm that most of the options in the current version provably provide privacy and authenticity, though some require slight modifications which we suggest. Our results complement the formal methods-based analysis of Kerberos that justifies its current design.