A note on the complexity of breaking Okamoto-Tanaka ID-based key exchange scheme
The rigorous security of Okamoto-Tanaka identity-based key exchange scheme has been open for a decade. In this paper, we show that (1) breaking the scheme is equivalent to breaking the Diffie-Hellman key exchange scheme over Z(n), and (2) impersonation is easier than breaking. The second result is obtained by proving that breaking the RSA public-key cryptosystem reduces to breaking the Diffie-Hellman scheme over Z(n) with respect to the polynomial-time many-one reducibility.
okamoto-tanaka key exchange scheme diffie-hellman rsa reducibility