In 1987, Desmedt first proposed a group oriented cryptosystem. During the past decade, group oriented cryptosystem has become one of the important cryptographical primitives. Laih and Harn proposed a generalized threshold cryptosystem with two models in 1991. In their system, each group is only assigned public key. A ciphertext can be decoded by utilizing all the secret keys owned by the users ...

At Eurocrypt ’96, Meyer and Müller presented a new Rabin-type cryptosystem based on elliptic curves. In this paper, we will show that this cryptosystem may be reduced to the cryptosystem of Rabin-Williams.

At Eurocrypt ’96, Meyer and Müller presented a new Rabin-type cryptosystem based on elliptic curves. In this paper, we will show that this cryptosystem may be reduced to the cryptosystem of Rabin-Williams.

In 1991, Damgård proposed a simple public-key cryptosystem that he proved CCA1-secure under the Diffie-Hellman Knowledge assumption. Only in 2006, Gjøsteen proved its CCA1-security under a more standard but still new and strong assumption. The known CCA2-secure public-key cryptosystems are considerably more complicated. We propose a hybrid variant of Damgård’s public-key cryptosystem and show t...

A recently proposed public key cryptosystem based on Chebyshev polynomials suggests a new approach to data encryption. But the security of the cryptosystem has not been investigated in depth, for lack of an appropriate analysis method. In this paper, a new representation of Chebyshev polynomial is introduced to study security issues of the cryptosystem. The properties of Chebyshev polynomial se...

Multibiometric Systems: Fusion Strategies and Template Security By Karthik Nandakumar Multibiometric systems, which consolidate information from multiple biometric sources, are gaining popularity because they are able to overcome limitations such as non-universality, noisy sensor data, large intra-user variations and susceptibility to spoof attacks that are commonly encountered in unibiometric ...

We describe a public-key cryptosystem with worst-case/average case equivalence. The cryptosystem has an amortized plaintext to ciphertext expansion of O(n), relies on the hardness of the Õ(n)-unique shortest vector problem for lattices, and requires a public key of size at most O(n) bits. The new cryptosystem generalizes a conceptually simple modification of the “Ajtai-Dwork” cryptosystem. We p...

A new secure knapsack cryptosystem based on the Merkle-Hellman public key cryptosystem will be proposed in this paper. Although it is common sense that when the density is low, the knapsack cryptosystem turns vulnerable to the low-density attack. The density d of a secure knapsack cryptosystem must be larger than 0 9408 . to avoid low-density attack. In this paper, we investigate a new Permutat...

Proxy cryptosystem, first proposed by Mambo and Okamoto [M.Mambo, E. Okamoto, Proxy cryptosystem: delegation of a power to decrypt ciphertexts, IEICE Trans. Fundam. Electron. Commun. Comput. Sci. E80-A/1 (1997) 54–63], allows the original decryptor to delegate his decrypting capability to the proxies. However, until now, no practical proxy cryptosystem modes are proposed. Therefore, in this pap...

In this article, the authors propose a protected on-line signature based biometric authentication system, where the original signature templates are protected by transforming them in a non-invertible way. Recovering the original biometrics from the stored data is thus computationally as hard as random guessing them. The transformed templates are compared employing a Dynamic Time Warping (DTW) m...