The Parallel High-Speed Word-based Nonlinear Functions

In this paper¹, we propose some parallel structures of the word-based nonlinear combine functions in word-based stream cipher, high-speed versions of general (bit-based) nonlinear combine functions. Especially, we propose the high-speed structures of popular four kinds in word-based nonlinear combiners using by PS-WFSR(parallel-shifting or parallel- structured word-based FSR): m-parallel word-based nonlinear combiner without memory, m-parallel word- based nonlinear combiner with memories, m-parallel word-based nonlinear filter function, and m-parallel word-based clock-controlled function. In addition, we propose an implementation example of the m-parallel word-based DRAGON stream cipher, and determine its cryptographic security and performance.