We present attacks against the McEliece Public-Key Cryptosystem, the Atjai-Dwork Public-Key Cryptosystem, and variants of those systems. Most of these systems base their security on the apparent intractibility of one or more problems. The attacks we present do not violate the intractibility of the underlying problems, but instead obtain information about the private key or plaintext by watching...

A repair of the Faure–Loidreau (FL) public-key code-based cryptosystem is proposed. The FL cryptosystem is based on the hardness of list decoding Gabidulin codes which are special rank-metric codes. We prove that the structural attack on the system by Gaborit et al. is equivalent to decoding an interleaved Gabidulin code. Since all known polynomial-time decoders for these codes fail for a large...

Existing finite automata public key cryptosystems (FAPKC) are analyzed in this paper. General types of cryptanalytic attacks on FAPKC are discussed and methods of breaking FAPKC by some known types of attacks are introduced. The times needed to perform the usual cryptanalytic attacks on FAPKC are calculated, in order to estimate processing complexity of those attacks. The contrastive analysis o...

The McEliece cryptosystem is one of the oldest public-key cryptosystem ever designated. It is also the first public-key cryptosystem based on linear error-correcting codes. The main advantage of the McEliece cryptosystem is to have a very fast encryption and decryption functions but suffers from a major drawback. It requires a very large public key which makes it very difficult to use in many p...

In 1984, Shamir [1] introduced the concept of an identity-based cryptosystem. In this system, each user needs to visit a key authentication center (KAC) and identify him self before joining a communication network. Once a user is accepted, the KAC will provide him with a secret key. In this way, if a user wants to communicate with others, he only needs to know the “identity” of his communicatio...

Certificateless public-key cryptosystem is a recently proposed attractive paradigm using public key cryptosystem, which avoids the key escrow inherent in identity-based public-key cryptosystems, and does not need certificates to generate trust in public keys. Recently, Al-Riyami and Paterson proposed a new certificateless public-key encryption scheme [2, 3] and proved its security in the random...

Nested certificates are used to certify their subject certificates. In this way, the subject certificates can be verified via their nested certificates without using signature verification methods based on public key cryptosystems. Such a verification method is called as subject certificate verification. In this paper, subject certificate verification method will be introduced. It will be shown...

\Fair" Public Key Cryptosystems (FPKCs) have recently been proposed as a method for providing secure escrowing of keys without relying on special purpose hardware. In a fair public key cryptosystem, the cryptosystem users are allowed to choose their own public and private keys, but they must share their secret keys with a group of trustees (escrow agencies) in a manner that allows the trustees ...

We present protocols for threshold cryptography in the GBD public-key cryptosystem. Both threshold decryption and threshold key generation are covered, in the “honest-butcurious” setting. This shows that it is possible to perform GBD computations in a distributed manner during both key generation and decryption, without revealing the private key to any party. GBD threshold decryption is similar...

We analysed and solved possible singularity for an improved MFE multivariate public key (Medium Field Multivariate Public Key Encryption) and studied the use of it in software copy protection. We used our new MFE multivariate public key cryptosystem to design an algorithm of software registration, in which a given plaintext can result in multi-cipher-text.. The breaking is hard because the ciph...