TEA, a Tiny Encryption Algorithm.

Introduction We design a short program which will run on most machines and encypher safely. It uses a large number of iterations rather than a complicated program. It is hoped that it can easily be translated into most languages in a compatible way. The first program is given below. It uses little set up time and does a weak non linear iteration enough rounds to make it secure. There are no preset tables or long set up times. It assumes 32 bit words. Encode Routine Routine, written in the C language, for encoding with key k[0] - k[3]. Data in v[0] and v[1]. void code(long* v, long* k) -- unsigned long y=v[0],z=v[1], sum=0, /* set up */ delta=0x9e3779b9, n=32 ; /* a key schedule constant */ while (n--?0) -- /* basic cycle start */ sum += delta ; y += (z!!4)+k[0] z+sum (z??5)+k[1] ; z += (y!!4)+k[2] y+sum (y??5)+k[3] ; /* end cycle */ v[0]=y ; v[1]=z ; Basics of the routine It is a Feistel type routine although addition and subtraction

Secondary Cosmic Ray Particles Due to GCR Interactions in the Earth's Atmosphere

Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface. Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations

The FLUKA Code: an Overview

FLUKA is a multipurpose Monte Carlo code which can transport a variety of particles over a wide energy range in complex geometries. The code is a joint project of INFN and CERN: part of its development is also supported by the University of Houston and NASA. FLUKA is successfully applied in several fields, including but not only, particle physics, cosmic ray physics, dosimetry, radioprotection, hadron therapy, space radiation, accelerator design and neutronics. The code is the standard tool used at CERN for dosimetry, radioprotection and beam-machine interaction studies. Here we give a glimpse into the code physics models with a particular emphasis to the hadronic and nuclear sector