Little Dragon Two: An efficient Multivariate Public Key Cryptosystem

TL;DR

This paper introduces Little Dragon Two, an improved multivariate public key cryptosystem that maintains efficiency while providing enhanced security against known attacks, with a public key structure similar to its predecessor.

Contribution

It proposes Little Dragon Two, a secure variant of the original Little Dragon cryptosystem, with a bijective public key algorithm suitable for encryption and signatures.

Findings

Achieves security against all known attacks on Little Dragon

Maintains similar efficiency and public key size as the original Little Dragon

Provides a bijective public key algorithm usable for encryption and signatures

Abstract

In 1998 [8], Patarin proposed an efficient cryptosystem called Little Dragon which was a variant a variant of Matsumoto Imai cryptosystem C*. However Patarin latter found that Little Dragon cryptosystem is not secure [8], [3]. In this paper we propose a cryptosystem Little Dragon Two which is as efficient as Little Dragon cryptosystem but secure against all the known attacks. Like Little Dragon cryptosystem the public key of Little Dragon Two is mixed type that is quadratic in plaintext and cipher text variables. So the public key size of Little Dragon Two is equal to Little Dragon Cryptosystem. Our public key algorithm is bijective and can be used for both encryption and signatures.