## CryptoDB

### Masao KASAHARA

#### Publications

Year
Venue
Title
2015
EPRINT
2015
EPRINT
2014
EPRINT
2014
EPRINT
2010
EPRINT
In this paper, we propose a new method for constructing the public-key cryptosystems based on a class of perfect error-correcting codes. The constructed PKC is referred to as K(IV)SE(1)PKC. In K(IV)SE(1)PKC, members of the class of perfect error correcting codes such as (7,4,3) cyclic Hamming code and (3,1,3) code {000,111} is used, yielding a simple process of encryption and decryption. The K(IV)SE(1)PKC has a remarkable feature that the coding rate can take on exactly 1.0 due to the use of perfect codes. Besides the size of the public key for K(IV)SE(1)PKC can be made smaller than that of the McEliece PKC.
2010
EPRINT
In this paper, we present a new scheme referred to as K(III) scheme which would be effective for improving a certain class of PKC's. Using K(III) scheme, we propose a new method for constructing the public-key cryptosystems based on error-correcting codes. The constructed PKC is referred to as K(V)SE(1)PKC. We also present more secure version of K(V)SE(1)PKC, referred to as K*(V)SE(1)PKC, using K(I) scheme previously proposed by the present author, as well as K(III) scheme.
2007
EPRINT
Extensive studies have been made of the Secret Sharing Scheme(SSS). In this paper new classes of SSS, referred to as K-SSS, $\rm{K_I}$-SSS, $\rm{K_{I\hspace{-.1em}I}}$-SSS and $\tilde{{\rm K}}$-SSS are presented on the basis of recovering algorithm, K-RA. As an application, we shall also present a method for the recovering of secret informations learned only by heart, based on a particular class of K-SSS, $\rm{K_I}$-SSS.
2005
EPRINT
In this paper, we present a new class of public-key cryptosystem (PKC) using algebraic coding on the basis of superimposition and randomness. The proposed PKC is featured by a generator matrix, in a characteristic form, where the generator matrix of an algebraic code is repeatedly used along with the generator matrix of a random code, as sub-matrices. This generator matrix, in the characteristic form, will be referred to as $K$-matrix. We show that the $K$-matrix yields the following advantages compared with the conventional schemes: \begin{description} \item [(i)] It realizes an abundant supply of PKCs, yielding more secure PKCs. \item [(i\hspace{-.1em}i)] It realizes a fast encryption and decryption process. \end{description}
2005
EPRINT
In Sept.1990, the present authors firstly discussed DLP over composite number and presented an ID-based Key Sharing Scheme referred to as MK1. In 1991, Maurer and Yacobi presented a scheme, referred to as MY, which is similar to our scheme, MK1. Unfortunately the schemes MK1 and MY are not secure. In Dec.1990, the present authors presented a secure ID-based key sharing scheme referred to as MK2. With a rapid progress of computer power for the last 15 years, our proposed scheme would have more chance to be applied practically. Regrettably, it has not been widely known that (i) the schemes MY and MK1 are not secure, (ii) there exists a secure scheme, MK2. In this paper, we shall review MK2 and clarify the difference between MK2 and other schemes from the standpoint of security.
2005
EPRINT
In this paper, we propose a new concept Meta Ring Signature''. Suppose that a signature text work as a public key, we may achive a new digital signature Meta Signature'' such that, the signer of a signature text, in this paper we call basic signature, can sign on to another message by using the basic signature text as the public key of Meta signature scheme. First, we present a concept of Meta Ring Signature such that both basic signature and meta signature are Ring Signature.
2003
EPRINT
Extensive studies have been made of the public-key cryptosystems based on multivariate polynomials . However most of the proposed public-key cryptosystems of rate 1.0 based on multivariate polynomials, are proved not secure. In this paper, we propose several types of new constructions of public-key cryptosystems based on two classes of randomly generated simultaneous equations, namely, a class based on bijective transformation and another class based on random transformation. One of the features of the proposed cryptosystems is that the sets of random simultaneous equations significantly improve the utilization factor of the public-key space. We show an example of the proposed cryptosystem whose size is only 100 bits that seems to be apparently secure in a sense that the utilization factor is significantly large compared with the conventional public-key cryptosystems.
2003
EPRINT
The pairings on elliptic curves have been applied for realizing the secure ID based cryptosystems that can be invulnerable to the collusion attacks. The computation of the pairing are necessary for the cryptosystems, though the computation of the pairing requires high cost compared with the computation cost for the power operation over the finite fields or on the elliptic curve when the parameters are securely to be provided. In this paper we propose an efficient method for a class of ID based cryptosystems which have been proposed by the present authors. The proposed method is able to reduce the number of the computations for the pairing for verifying the ID based signature and also for decoding of the ID based public key cryptosystems with the authentication, by a factor of 2. Moreover we propose the ID based public key cryptosystems with signature and the ID based public key cryptosystems having the multiple centers.

#### Coauthors

Yasuyuki MURAKAMI (1)
Hiroyuki OKAZAKI (1)
Ryuichi SAKAI (3)