Secure group communication using fractional public keys

In this paper, we present the novel concept of fractional public keys and an efficient zero-round multi-party Diffie-Hellman key agreement scheme that is based on fractional public keys. Shared group keys are computed highly efficiently by using the fractional public keys of multiple participants as exponents. The scheme provides therefore an efficient and elegant way of multi-party key agreement without key establishment data transmissions. The presented cryptographic scheme is collusion resistant to any number of users.