Cryptmt Stream Cipher Version 3

In the previous manuscripts, we proposed CryptMT pseudorandom number generator (PRNG) for a stream cipher, which is a combination of (1) an F2-linear generator of a wordsize-integer sequence with a huge state space, and (2) a filter with one wordsize memory, based on the accumulative integer multiplication and extracting some most significant bits from the memory. No valid attacks have been reported so far. In this manuscript, we propose a modification of the algorithm to speed up the generation and the initialization, by (1) using the parallelisms such as pipelining and single-instruction-multiple-data (SIMD) operations included in modern CPUs, (2) in the filter, raising the ratio between the numbers of output bits and the input bits from 1/4 to 1/2. As a result, we propose the CryptMT Version 3 which has 1.8 times faster generation and 48.7 times faster initialization than the Version 1, while the security level seems comparable to the original version. The generation/initialization speed is comparable to the fast stream ciphers such as SNOW2.0. Moreover, CryptMT Version 3 is proved to have a period that is a multiple of 219937 − 1 and strong resistance to the standard attacks.