Random number generator for cryptography

Abstract

One key requirement for many cryptograhic schemes is the generation of random numbers. Sequences of random numbers are used at several stages of a standard cryptographic protocol. One simple example is a Vernam cipher, where a string of random numbers is added to message string to generate encrypted code. C = M ⊕ K. It has been mathematically shown that this simple scheme is unbreakable if key K is as long as M and is used only once. The security of a cryptosystem shall not be based on keeping the algorithm secret but solely on keeping the key secret. The security of a random number generator (RNG) is related to the difficulty of predicting its future sequence values from past values. The quality and unpredictability of secret data is critical to securing communication by modern cryptographic techniques. The generation of such data for cryptographic purposes typically requires an unpredictable physical source of random data. We studied a chaotic circuit which consisted of an inductor, capacitance, diode and thus used for the BB84 protocol. We have studied both pseudo random and true random number generators and evaluated them through various tests like frequency, correlation, NIST etc.

Atmospheric effects on Quaternary polarization encoding for free space communication

“…But since the two distributions are not overlapping each other, an unambiguous bit designation can still be performed, which shows a higher tolerance for noise, as shown in our earlier work [11]. We have also shown in the earlier work that the measure of SOP obtained, is actually due to due to the ballistic and snake photons [13,14,11] whereas those that undergo significant depolarization cancel out each other. In this communication, we test this method with other polarizations, which will form components of a Quaternary encoding.…”

“…In additon, as we show in this communication, the depolarization behaviour is different for different encodings, adding additional difficulty, which is peculiar to M-ary encodings. But our method of differential measurement, as shown earlier [11], will allow us to extract information with a near zero bit error rate despite a significant depolarization.…”

“…• 11 horizontal The experimental setup is similar to the one explained in our earlier paper [11], briefly explained here for sake of completeness. It consists of two lasers L1 and L2, both VCSEL's operating at 780nm.…”

“…It was shown in reference [11] that the value of SOP is determined only by snake and ballistic photons which retain their polarization and the depolarized part of the light will cancel out and does not affect the SOP. We show below the same results using a full Stokes vector analysis.…”

“…We first briefly describe our experimental setup, which is same as the one used in [11]. We then present the results for errors due to depolarization, first for vertical and horizontal encoding and then independently for 45…”