There are two basic types of symmetric algorithms: block ciphers and stream ciphers. Block ciphers operate on blocks of plaintext and ciphertext—usually of 64 bits but sometimes longer. Stream ciphers operate on streams of plaintext and ciphertext one bit or byte (sometimes even one 32-bit word) at a time. With a block cipher, the same plaintext block will always encrypt to the same ciphertext ...

In this paper we design a stream cipher that uses the algebraic structure of the multiplicative group Z Z * p (where p is a big prime number used in ElGamal algorithm), by defining a quasigroup of order p − 1 and by doing quasigroup string transformations. The cryptograph-ical strength of the proposed stream cipher is based on the fact that breaking it would be at least as hard as solving syste...

The ZK-Crypt combination compact hardware stream cipher engines each include a true random number generator, a stream cipher and a data authenticator based on a fast compact engine and proven "noise sources". The ZK-Crypt II 7.0 K gate and ZK-Crypt 8.2 K gate "engines" output a 32 bit word at each clock cycle with 128 and 160-bit keys, maximizing throughput with very low energy per enciphered b...

In this paper, we propose a new hardware friendly authenticated encryption (AE) scheme TriviA based on (i) a stream cipher for generating keys for the ciphertext and the tag, and (ii) a pairwise independent hash to compute the tag. We have adopted one of the ISOstandardized stream ciphers for lightweight cryptography, namely Trivium, to obtain our underlying stream cipher. This new stream ciphe...

We propose and analyze the Lizard-construction, a way to construct keystream generator (KSG) based stream ciphers with provable 2 3 n-security with respect to generic time-memory-data tradeoff attacks. Note that for the vast majority of known practical KSG-based stream ciphers such attacks reduce the effective key length to the birthday bound n/2, where n denotes the inner state length of the u...