Abstract: The present invention includes a method and device for calculating an encryption key, K?c, for use in the initialization of an encryption algorithm. The present invention discloses a method for calculating the encryption key, K?c(x), by obtaining a ciphering key, Kc(x), determining a maximum ciphering key length, L, based on the requirements of the two devices wishing to communicate, and determining a maximum usable encryption key length, Lmax. The ciphering key, Kc(x), is then manipulated through an addition function or an exclusively-or function with a polynomial g1(x). The result is multiplied with a polynomial g2(x), which spreads the starting points of said encryption key, K?c(x). The encryption key is thus determined according to K?c(x)=g2(L)(x)[Kc(x) mod g1(L)(x)]. The method of calculating the encryption key, K?c, ensures that a maximum ciphering key length is not exceeded. In addition, the method provides new possible starting points each time a new encryption key, K?c, is generated.

Abstract: A highly efficient mix network for small numbers of inputs is provided. Four data messages would be a typical number of inputs. The structure of sorting/permutation networks is used to permute the input. This is done in a way that changes the position of pairs of items. A mix network is provided which is highly efficient on small input batches and is robust and private in the face of collusion by any minority set of mix servers. Additionally, the mix network method and apparatus has the feature of being publicly verifiable because the mixing method yields a transcript of results that can demonstrate to a third party that the mix proceeded correctly. An apparatus comprised of a plurality of mix servers is provided. Each mix server includes a randomizer network. Each randomizer network receives a plurality of input data messages and performs re-encryption and permutation operations on the plurality of input data messages to form a plurality of output data messages.

Abstract: A stream cipher cryptosystem includes a pseudo-random number generator receiving a key and providing a keystream. A cryptographic combiner combines a first binary data sequence and the keystream with a one's complement operation to provide a second binary data sequence. In encryption operations, the cryptographic combiner is an encryption combiner and the first binary data sequence is a plaintext binary data sequence and the second binary data sequence is a ciphertext binary data sequence. In decryption operations, the cryptographic combiner is a decryption combiner and the first binary data sequence is a ciphertext binary data sequence and the second binary data sequence is a plaintext binary data sequence.