International Association
for Cryptologic Research

Recent revelations about government surveillance have significantly

increased the demand for end-to-end secure communications. However, key management remains a major barrier to adoption. Current

systems are often either vulnerable to a malicious or coerced key directory or they make unrealistic assumptions about user behavior,

for example, that users will verify key fingerprints out of band.

We present CONIKS, a system that provides automated key management for end users capable of seamless integration into existing secure messaging applications. In CONIKS, key servers maintain consistent directories of username-to-public key bindings that

allow participants to detect any equivocation or unexpected key

changes by malicious key servers. CONIKS also preserves user\'s

privacy by ensuring that adversaries cannot harvest large numbers

of usernames from the directories. Our prototype chat application

extends the Off-the-Record Messaging plug-in for Pidgin. A single

commodity server can support up to 10 million users and clients

need only download less than 100 kB per day of additional data.