Cryptology ePrint Archive: Report 2004/366

Piece In Hand Concept for Enhancing the Security of Multivariate Type Public Key Cryptosystems: Public Key Without Containing All the Information of Secret Key

Shigeo Tsujii and Kohtaro Tadaki and Ryou Fujita

Abstract: We propose a new concept, named piece in hand, which can be applicable to a wide class of multivariate type public key cryptosystems to enhance their security. The piece in hand provides such cryptosystems with a new type of trapdoor which is compatible with the trapdoor originally equipped in them. The piece in hand concept is based on a new paradigm for public key cryptosystem in general. On the one hand, in most traditional public key cryptosystems such as the RSA and ElGamal schemes, the public key contains all the information of the secret key. On the other hand, in our scheme, the piece in hand, which is a part of the secret key, is not contained in the public key but is taken from outside of the public key to plug in during the decryption. In this paper, we illustrate how to apply the piece in hand concept to enhance the security of multivariate type public key cryptosystems, by presenting the general theory for the use of the concept.

Category / Keywords: public-key cryptography / public-key cryptography, multivariate polynomial, multivariate type public-key cryptosystem

Date: received 16 Dec 2004

Contact author: tadaki at kc chuo-u ac jp

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Version: 20041220:211740 (All versions of this report)

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