Sciweavers

Share
EUROCRYPT
2004
Springer

Secure Hashed Diffie-Hellman over Non-DDH Groups

11 years 3 months ago
Secure Hashed Diffie-Hellman over Non-DDH Groups
We show that in applications that use the Diffie-Hellman (DH) transform but take care of hashing the DH output (as required, for example, for secure DH-based encryption and key exchange) the usual requirement to work over a DDH group, i.e., a group in which the Decisional Diffie-Hellman assumption holds, can be relaxed to only requiring that the DH group contains a large enough DDH subgroup. In particular, this implies the security of (hashed) Diffie-Hellman over non-prime order groups such as Z p . Moreover, our results indicate that one can work directly over Z p without requiring any knowledge of the prime factorization of p-1 and without even having to find a generator of Z p . These results are obtained via a general characterization of DDH groups in terms of their DDH subgroups, and a relaxation (called t-DDH) of the DDH assumption via computational entropy. We also show that, under the short-exponent discretelog assumption, the security of the hashed Diffie-Hellman transform is...
Rosario Gennaro, Hugo Krawczyk, Tal Rabin
Added 20 Aug 2010
Updated 20 Aug 2010
Type Conference
Year 2004
Where EUROCRYPT
Authors Rosario Gennaro, Hugo Krawczyk, Tal Rabin
Comments (0)
books