RC4: Day 7

Collisions for RC4-Hash

RC4-Hash is a variable digest length cryptographic hash function based on the design of the RC4 stream cipher. In this paper, we show that RC4-Hash is not collision resistant. Collisions for any digest length can be found with an expected effort of less than 2 compression function evaluations. This is extended to multicollisions for RC4-Hash. Finding a set of 2 colliding messages has an expecte...

PC-RC4 Algorithm: An Enhancement Over Standard RC4 Algorithm

RC4 is most widely used stream cipher. In many standard security protocols is used the RC4 like in Wi-Fi Protocol Access (WPA) and Wired Equivalence Privacy (WEP). Here we propose a new enhanced RC4 algorithm named as PC-RC4. It is an extension of standard RC4 Algorithm. The basic purpose of this enhancement is to making strong RC4 algorithm. RC4 stream cipher is basically two stages process na...

World Health Day, 7 April 2001.

Burkard 7 Day Recording Volumetric Spore Sampler

STANDARD OF REFERENCE Built and developed with the assistance of scientists closely associated with problems relating to airborne particles such as fungus spores and pollens, the sampler has proved to be a standard of reference throughout the world. Although the instrument compares closely to the trap described by Hirst in 1952 (Ann app. Biol 39 pp. 257-265) its performance has been enhanced by...

World Health Day — April 7, 2013

Hypertension affects one third of adults in the United States (1) and is a major risk factor for heart disease and stroke (2). A previous report found differences in the prevalence of hypertension among racial/ethnic populations in the United States; blacks had a higher prevalence of hypertension, and Hispanics had the lowest use of antihypertensive medication (3). Recent variations in geograph...