### A Cryptosystem Based on Hidden Order Groups and Its Applications in Highly Dynamic Group Key Agreement

Amitabh Saxena and Ben Soh

##### Abstract

Let $G_1$ be a cyclic multiplicative group of order $n$. It is known that the Diffie-Hellman problem is random self-reducible in $G_1$ with respect to a fixed generator $g$ if $\phi(n)$ is known. That is, given $g, g^x\in G_1$ and having oracle access to a Diffie-Hellman Problem' solver with fixed generator $g$, it is possible to compute $g^{1/x} \in G_1$ in polynomial time. On the other hand, it is not known if such a reduction exists when $\phi(n)$ is unknown. We exploit this `gap'' to construct a cryptosystem based on hidden order groups by presenting a practical implementation of a novel cryptographic primitive called \emph{Strong Associative One-Way Function} (SAOWF). SAOWFs have interesting applications like one-round group key agreement. We demonstrate this by presenting an efficient group key agreement protocol for dynamic ad-hoc groups. Our cryptosystem can be considered as a combination of the Diffie-Hellman and RSA cryptosystems.

Available format(s)
-- withdrawn --
Category
Public-key cryptography
Publication info
Published elsewhere. Unknown where it was published
Contact author(s)
amitabh123 @ gmail com
History
2006-02-27: withdrawn