# Tag Info

## New answers tagged random-number-generator

0

In most PRNGs this leads to a total disaster, in particular when generator's state is bigger than the result returned as pseudo random (call to rand()). If you take Mersenne Twister with it's big period guaranteed and apply the construction you expose, as it returns 32 bit integers, eventually you will get a repeated value that was used to seed previously, ...

1

A lot of companies use BSAFE: for a long time, BSAFE was the most successful supported cryptographic toolkits: it predates the success of open source software, it predates the availability of crypto APIs in operating systems, and it predates the expiration of patents on RSA and public-key cryptography in general. And it's always been a reliable, well-tested, ...

2

The process of turning inputs that are hard to predict (formally, inputs that have some min-entropy) into bit strings that are cryptographically uniformly random is called entropy extraction. So there's your search term if you want to learn more theory. The problem. The fact that your outputs produce values that can pass a given statistical test (or even a ...

4

I've found this attack to be poorly documented, all-in-all. Below is a technical explanation of the matter, or one can skip to the conclusion if uninterested in the details. Dual_EC_DRBG First, let me give a short description of Dual_EC_DRBG using the notation of Shumow and Ferguson (see the presentation). As a preliminary, we are working with some ...

0

The value in question is the logarithm of one point to the base of a second point. Computing discrete logarithms on the curves in question is generally considered to be very hard.

4

Suppose g is a PRNG. $\:$ Define G by the following pseudocode: def G(w): m = length(w) n = ceiling(m/2) set x equal to the n leftmost bits of w set y equal to the m-n rightmost bits of w z = concatenate(g(x),y) output z In this case, G is a PRNG and G' is not a PRNG.

0

One thing you can do if you are not too concerned about losing some entropy is this: For the numbers 0 through 9, divide them evenly into two groups. Assign a 0 bit to any number that occurs in the first group, and a 1 bit for any number that occurs in the second group. For example: 0 = 0 1 = 0 2 = 0 3 = 0 4 = 0 5 = 1 6 = 1 7 = 1 8 = 1 9 = 1 Or you might ...

1

Proof of security: Let (x_1, ..., x_n) be the messages you caught. Let (p_1, ...) and (q_1, ...) be three streams of random messages known to both communication partners. Let these be from a true random number source generating non-autocorrelated data. Let (n_1, ...) be another stream of data from the same source. Since there is no correlation, it is ...

1

Germany's BSI has produced AIS 31 that includes requirements on Physical True RNGs (PTRNGs). It is designed to fill a gap in the Common Criteria standard. Chapter 4 describes pre-defined classes for physical true, non-physical true, deterministic and hybrid random number generators. ... The basic concepts and evaluation criteria are illustrated by ...

6

As far as I can tell, NIST has only one official document about entropy collection. SP-800-90B. The purpose of NIST Special Publication (SP) 800-90B is to specify the design and testing requirements for entropy sources that can be validated as approved entropy sources by NIST‘s CAVP and CMVP. It essentially defines a bunch of statistical tests to ...

1

A PRNG with a seed $S$ whose output is combined with the plaintext is called a stream cipher with the key $S$. So assuming that the details are filled in correctly, what you're describing is a stream cipher algorithm with two session keys, one used in each direction. Each seed/key must be unique, and the combination must ensure that each output bit has a ...

4

/dev/urandom itself is an acceptable crypto-quality (P)RNG. Therefore it can't hurt security to call it as often as you want. Assuming that /dev/urandom operates correctly (i.e. returns bit that cannot be predicted), the probability for an observer to correctly predict the bits generated by drbgFromSeed decreases (very slowly) with the number of generated ...

2

No, it would not be secure… especially not without specific precautions and protocol implementations – which random.org doesn't offer in the first place. Also, random.org is – as far as I know – not certified, which downgrades it from a “trust” point of view. But when talking about such randomness providers, I always like to mention a more professional ...

Top 50 recent answers are included