PEKE, Probabilistic Encryption Key Exchange, 10 Years Later, Including the PEKEv1.25 Specifications

This document revisits the PEKE (Probabilistic Encryption Key Exchange) cryptosystem and proposes the enhanced PEKEv1.25 that performs a hash computation on the original PEKE output in order to improve the security assurance and to broaden the field of use. For a key establishment application where only the server side publishes a long-term public key and can adequately protect the private key counterpart from implementation attacks, we claim that PEKE is unsurpassed in security and efficiency, among the finite field arithmetic cryptosystems (e.g. RSA and finite field Diffie-Hellman). We use an original definition for the type of key encapsulation service provided by PEKE, hoping that this abstract definition captures the characteristics of the protocol and usage context. However, we only suggest that related security proofs are encouraging for the security of PEKE