Csh: A post-quantum secret handshake scheme from coding theory

Abstract

In secret handshake schemes, the members in the same organization can anonymously authenticate each other and commonly negotiate a secret key for communication. Since its proposing in 2003, secret handshake schemes become an important privacy protection cryptographic technique on internet applications. In this paper, a secret handshake scheme based on coding theory (we call $$\mathsf {CSH}$$) is presented. This is the first code-based secret handshake scheme. $$\mathsf {CSH}$$ is constructed by combining the CFS signature system and Stern’s identification system, thus the security of $$\mathsf {CSH}$$ relies on the syndrome decoding problem just like the two above systems. Moreover, as far as we know, $$\mathsf {CSH}$$ is the first scheme to use a generic construction of Fiat-Shamir paradigm in secret handshake schemes. This may lead to a more generic framework construction.