We present protocols for threshold decryption and threshold key generation in the GBD public-key cryptosystem in the “honest-butcurious” setting. These allow GBD computations to be performed in a distributed manner during both key generation and decryption, without revealing the private key to any party. GBD threshold decryption is similar to El-Gamal threshold decryption. GBD threshold key gen...

Guo et al. recently presented a reaction attack against the QC-MDPC McEliece cryptosystem. Their attack is based on the observation that when a bit-flipping decoding algorithm is used in the QC-MDPC McEliece, then there exists a dependence between the secret matrix H and the failure probability of the bit-flipping algorithm. This dependence can be exploited to reveal the matrix H which constitu...

K. Yoneyama et al. introduces the Leaky Random Oracle Model at ProvSec2008, which only considers the leakage of the hash list of a hash function used by a cryptosystem due to various attacks caused by implementation or sloppy usages. However, an important fact is that such attacks not only leak the hash list of a hash function, but also leak other secret states outside the hash list of a crypto...

In this paper we break a knapsack based two-lock cryptosystem proposed at ICICS’03 [7]. The two-lock cryptosystem is a commutative encryption algorithm that is very useful for the construction of the general t-out-of-n oblivious transfers and millionaire protocol. However, our analysis shows that the proposed knapsack based two-lock cryptosystem is extremely insecure. The serious flaw is that t...

Abstract Key-insulated encryption reduces the problem of secret key exposure in hostile setting while signcryption cryptosystem attains benefits digitally signing a ciphertext and public cryptosystem. In this study, we merge primitives parallel key-insulation with equality test to construct ID-based key-insulated for (ID-PKSET) cloud computing. The construction prevent data forgery, re-play att...

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 ...

In a group-oriented threshold cryptosystem, each group, instead of each individual member within the group, publishes a single group public key. An outsider can use this group public key to send encrypted messages to the group. However, the received encrypted messages can only be decrypted properly when the number of participating members is larger than or equal to the threshold value. All earl...

Key management represents a major and the most sensitive part of cryptographic systems. It includes key generation, key distribution, key storage, and key deletion. It is also considered the hardest part of cryptography. Designing secure cryptographic algorithms is hard, and keeping the keys secret is much harder. Cryptanalysts usually attack both symmetric and public key cryptosystems through ...

In a classical cryptosystem, as opposed to a public-key cryptosystem, communication between users is based on a secret key known to them, but no others. A key-distribution protocol is employed to distribute copies of this secret key to the users. One simple way to perform key-distribution makes use of out-of-band communication a diplomatic courier, for example. More desirable for a computer net...

This article defines a new algorithm for a secret key cryptosystem using cellular automata which is a promising approach to cryptography. Our algorithm is based on cellular automata built on a set of reversible rules which have the ability to construct unpredictable secret keys using MARGOLUS neighborhood. To prove the feasibility of the algorithm, we present some tests of encryption, decryptio...