The principle of compressed sensing (CS) can be applied in a cryptosystem by providing the notion of security. In this paper, we study the computational security of a CS-based cryptosystem that encrypts a plaintext with a partial unitary sensing matrix embedding a secret keystream. The keystream is obtained by a keystream generator of stream ciphers, where the initial seed becomes the secret ke...

In this paper, a novel key management model and algorithm for two-tier architecture network are proposed based on elliptic curve cryptosystem (ECC) combined with public key (CPK) technology, verifiable secret sharing technology, and two-tier architecture network technology. This novel key management algorithm is composed of several sub-algorithms, such as key generation, key update, nodes joini...

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...

The asymmetric cryptosystem plays an important role in the cryptology nowadays. It is widely used in the fields of data encryption, digital watermarking, digital signature, secure network protocol, etc. However, with the improvement of computing capability, longer and longer the key length is required to ensure the security of interaction information. To shorten the key length and improve the e...

The topic of this thesis is established in the area of mathematical cryptology, more preciselyin group based cryptology. We give extensions of cryptographic protocols, develop new crypto-graphic protocols concerning the mathematical background and give modifications of them. Inaddition cryptographic analysis as well as examples are given. The focus lays on the developmentof new ...

Polar codes are novel and efficient error correcting codes with low encoding and decoding complexities. These codes have a channel dependent generator matrix which is determined by the code dimension, code length and transmission channel parameters. This paper studies a variant of the McEliece public key cryptosystem based on polar codes, called"PKC-PC". Due to the fact that the structure of po...

In this paper we propose an efficient multivariate public key cryptosystem. Public key of our cryptosystem contains polynomials of total degree three in plaintext and ciphertext variables, two in plaintext variables and one in ciphertext variables. However, it is possible to reduce the public key size by writing it as two sets of quadratic multivariate polynomials. The complexity of encryption ...

We report experiments on the security of the GGH-like cryptosystem proposed by Micciancio. Based on these experiments, we conclude that the system can be securely used only in lattice dimensions ≥ 782. Further experiments on the efficiency of the system show that it requires key sizes of 1MByte and more and that the key generation as well as the decryption take inacceptibly long. Therefore, Mic...

This paper presents a survey of key evolving cryptosystems in the public key setting, focusing on two main approaches: ‘forward security’ and ‘intrusion resilience’. The essential feature of this design strategy is that the secret key changes over time, while the corresponding public key remains unchanged. Key evolving cryptosystems can limit the damage caused by an attacker who occasionally le...

We propose a cryptosystem that has an inherent key escrow mechanism. This leads us to propose a session based public verifiable key escrow system that greatly improves the amount of key material the escrow servers has to keep in order to decrypt an encryption. In our scheme the servers will only have a single secret sharing, as opposed to a single key from every escrowed player. This is done wh...