Questions tagged [random-number-generator]
A random number generator is a software or hardware solution which functions as a generator of (real or pseudo) random numbers (or bits).
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Why does the NIST CTR DRBG apparently output the internal state when no additional input is given?
After reading through the specification of the FIPS CTR_DRBG in SP 800-90A (see Section 10.2.1), I got the impression that the output of the DRBG coincides with its internal state as long as no ...
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2answers
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Are there any practical differences between running a PRNG on a subset of bits from an RNG compared to running the RNG?
Given an RNG and a PRNG.
We define RNG(k) to mean that the RNG produces k random bits.
We define PRNG(k, seed) to mean that the PRNG uses seed to produce k pseudo-...
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1answer
30 views
Side-channel resistant discrete uniform sampling on $d\neq 2^t$ values?
Assume you have some source of $\mathsf{Bern}(1/2)$'s (probably some CSPRNG in practice). What is generally done to sample from $\mathsf{Unif}([d])$ in a side-channel resistant way (assuming $d$ isn't ...
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1answer
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Interpretation of certain results of NIST Test Suite
I am using NIST Test suite on a PRNG and have a confusion regarding some specific results. Following is the part of the results:
...
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2answers
45 views
Derive operations from an arbitrary number
I don't really know how to phrase this question, so I'll just mention the idea. This is partially reminiscent (at least in spirit to white box crypto): Can one derive arithmetic operations from a ...
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1answer
36 views
Given a point $c$ in a field $Z_p$. Can we get another value $c^{'}$ such that $\left(c^{\prime}-c\right)$ is invertible in $Z_p$?
If we have a point in a field $c$. Can we get another value $c^{'}$ such that
$\left(c^{\prime}-c\right)$ is invertible in $Z_p$ ?
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1answer
179 views
Asymmetric CSPRNG where the public key only works backward
Is there an asymmetric cryptographically secure pseudo random number generator in which the public key only goes backward? For example, I'd like to generate 5,000 digits, then provide the public key ...
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3answers
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Can we assume that a hash function with high collision resistance also means a highly uniform distribution?
I want to use a hash function to generate a random sequence from number 0-n. And so I would like to find a good function that results in values that are seemingly random (does not need to be secure), ...
3
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2answers
89 views
Does a regularly reseeded PRNG provide backtracking resistance?
I'm currently discussing a security topic with some of my classmates.
A cryptographic PRNG typically provides backtracking resistance if an adversary that compromises the internal PRNG state cannot ...
2
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1answer
71 views
Mapping between NIST test and TRNG features
Each of the NIST tests are generally explained in Random Bit Generation - Guide to the Statistical Tests. I was wondering if some one can help me understand them better. For example, which tests show ...
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1answer
120 views
Understanding $\varepsilon$-advantage in cryptographically secure deterministic RNG
In Efficient and Secure Pseudo-Random Number Generation by Vazirani & Vazirani, it is stated that every pseudorandom number generator which satisfies the XOR Condition can securely output $\log n$ ...
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1answer
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Stream cipher — Are all random bit generators suitable for stream cipher?
I learned the stream cipher using LFSR in the book. I wonder whether all random bit generators (i.e. BBS, Rabin generator) are suitable for stream cipher. I search using keywords "stream cipher" and "...
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Is it possible to use a XOF function as csrng? [duplicate]
Let's say we "seed" a xof function (eg. SHAKE256) with x cryptographically random bytes (enough so that they can't be bruteforced), could said function be used as a cryptographically secure random ...
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1answer
68 views
Why is LCG PRNG chosen to be as c++ rand() function?
The C++ rand() function is an Linear Congruential Generator (LCG) PRNG. my questions are:
Why was this algorithm chosen?
What are the pros and cons?
Is it good for cryptography?
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1answer
130 views
Using a non-secure random generator for IV or salt generation
I was just looking at a post on Code Review when I noticed the other answer to the post. While I would agree mostly with the answer, I do however doubt if having a Cryptographically Secure PRNG is ...
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3answers
203 views
Can a deck of cards be used as a practical source of cryptographic randomness?
This is not a duplicate of Entropy measurement from shuffled cards, as this concerns use of cards as a cryptographic entropy source, rather than calculating entropy from some number of cards.
The ...
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1answer
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Is openssl rand command cryptographically secure?
I'm wondering if the openssl rand command produces cryptographically secure random bytes. For example when in need for a random password or token:
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3
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2answers
89 views
How to make a hypothesis test for a simple statistical test for a certain RNG?
I'm self-studying about hypothesis test in the context of RNGs. I'm building a hypothesis test from scratch. I'm taking the simplest statistical test I can think of: how many $1$s are there in the ...
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3answers
154 views
Are XOFs and KDFs more usable than DRBGs?
CSPRNGs have 2 design requirements:
output unpredictability,
back-tracing resistance.
In addition to which, NIST SP 800-90Ar1 added other features such as a) instance customization/personalization,...
2
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2answers
161 views
Why should one model an entropy source in order to build a TRNG?
Some assert that a theoretical model of the unconditioned source must be created when building any TRNG. It's believed to be a fundamental requirement. So a few related questions arise:-
What is a "...
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1answer
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Brute forcing/hacking Secure passphrases - difficulty for random strings vs real words
I was wondering about this topic of brute forcing passwords,or ANY other way to deriving them - and asking myself whats more secure (relatively):
A Password which includes
A) 30 digits length- a ...
0
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2answers
66 views
secret and unique random number generator within a range
I am trying to think of a way to generate secret and unique random numbers within a range.
Say we have a public range [1-n], how could we have a maximum of n users choose a random number within this ...
2
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1answer
167 views
What are implementations of PRNGs based on ChaCha20? [closed]
I thought I'd find an implementation in NaCl, but /dev/urandom is what I find. Search engines samples revealed most implementations are broken.
What libraries are ...
2
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3answers
188 views
Low entropy - how does it compromise the crypto
One of the often pointed out mistake in dealing with crypto is not having enough entropy in the system. Without enough entropy the random numbers generated are not random enough.
But what I am not ...
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2answers
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How was the 5 digit random number in the VIC cipher generated?
Knowing that VIC was a "spy cipher" it is unlikely that the agents used a cryptographic device to genreate the 5 digit number but how did they do it?
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3answers
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Hardware RNG Bias
I have generator based on sampled noise (reverse-biased transistor - actually ChaosKey but that's not that important).
The noise source is fed into ADC and sampled with 16bit resolution (2 bytes). ...
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1answer
56 views
Method for generating random number(s) [closed]
I was reading about random numbers and their usage in security. I'd like to verify with more experienced people how good this method of generating random numbers will be.
Human beings are very hard ...
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1answer
140 views
Distinguishing generators of RSA primes and moduli
We are trying to distinguish two RSA prime generators:
Prime generator 1
draw uniformly at random an integer $p$ with $2^{1023.5}<p<2^{1024}$, until it is prime
output $p$.
Prime generator 2
...
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2answers
2k views
Example of cryptography random number
I read that random numbers are being used in cryptography and security. I think I have idea how to truly generate true random, non-deterministic number. But before continuing further I'd like to ask ...
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0answers
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Generating sets of unreadable/secure and unique random numbers
In the process of doing some research, I stumbled across the following two claims on the PokerStars website.
We do record all of the hole cards in all real money hands. This is an
important tool ...
2
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1answer
143 views
In the Linux Kernel 4.8+, does the CSPRNG update the entropy pool?
My understanding of how /dev/urandom works is that the kernel collects true randomness from a variety of sources, and mixes them together to remove statistical bias. It does this at regular intervals ...
4
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1answer
376 views
Salsa20 as a PRNG with streams
Can I use Salsa20 as a good non-cryptographic PRNG with different streams if I reduce the number of rounds to 8 and omit the addition step at the end? I want to omit the final step because I don't ...
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160 views
Set passes Dieharder randomness with ints values, fails when ints are split into bytes
I've generated 100M of random numbers in range (0..255). These numbers fail Dieharder tasts (bitnum = 8). However, I can pass this test by combining four bytes into an int.
Randomness of the set didn'...
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1answer
84 views
Can POS devices really generate random numbers?
I am doing an implementation of a system designed by a payment company and I am a little skeptical about the way they have designed the end to end cryptography.
The system is as follows:
There are ...
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5answers
875 views
Entropy vs predictability in PRNGs
If entropy is the measure of surprise, and a given PRNG has a uniform distribution, then the entropy would be high. So the Mersenne Twister(MT) has high entropy.
But the MT is also predictable. You ...
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0answers
96 views
How to get unknown constants from linear congruential generator
I need to crack this linear congruential generator.
I have
$$X_{n+1}=a⋅X_n +b \pmod m$$
I know: $m=31,X_3=30,X_4=19,X_5=26$
How can I find $a,b$ and $X_0$?
I have got already the following ...
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2answers
185 views
Aes Ctr non-secure PRNG
I want to construct a seeder for a big state PRNG (xorshift1024 based) and have been thinking about using Aes Ctr using multiple 256 bit keys, where the counter is simply encrypted multiple times (...
3
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2answers
221 views
Implementing randomness extractors
A randomness extractor is a function that takes an input sampled from high entropy distribution and outputs a value that is close to uniform distribution. It is slightly different from a PRG. PRGs ...
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1answer
246 views
Exactly what RNG weaknesses endanger (EC)DSA?
RFC 6979 defines deterministic variants of (EC)DSA. It states in introduction
One characteristic of DSA and ECDSA is that they need to produce, for each signature generation, a fresh random ...
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2answers
442 views
Choosing a Random Number Generator algorithm to encrypt a message
What are the best cryptographically secure pseudo-random number generator algorithms, and what are their strengths/weaknesses? I can't seem to come up with a list of them (or maybe I do, but they ...
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3answers
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Cryptography's random number problem?
Sophie Chen at Wired Magazine;
quantum mechanics could solve cryptography's random number problem
Such machine already exist, but it's too huge and not so fast in order to use it all the time.
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0answers
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Do any bits from the standard Mersenne Twister repeat more often than the total period? [closed]
While the total period of MT19937 is $2^{19937}-1$ by design, is the period of the sequence of any of the individual bits from the output less than this? I'll admit I'm far too unfamiliar with group ...
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2answers
325 views
Interpretation of (NIST) Non Overlapping Template Matching Test
Regarding the Non-Overlapping Template test, this test normally gives us a bunch of p-values (148 values). I would like to ask that how do we interpret those values into a single p-value for ...
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2answers
101 views
Is it possible to test 15-bit PRNG with the library TestU01?
The library TestU01 inconvenient for generators that don't produce 32-bit outputs. But is it possible to somehow test say a 15-bit generator with it? How could that be done?
For instance, the ...
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2answers
141 views
Blockchain cryptography
I'm a high school student doing a project about blockchain. I'm trying to figure out why hashing algorithms are crucial for the existence of blockchain and other types of cryptography wouldn't work. ...
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1answer
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How might one create a system of election by lot (sortition) that is both secure and verifiable?
I've been puzzling recently over sortition, a democratic method of selection for public office which I find very fascinating. Basically, instead of choosing candidates like Hillary Clinton or Donald ...
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Do hash functions need to “look random”?
I've noticed that looking random is not often listed as a requirement for a good hash function in the same way that preimage or collision resistance is.
Do we need hash functions to look random?
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2answers
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What is the difference between TRNG and CSPRNG?
I understand the output of a TRNG is almost impossible to reproduce, such a flipping a coin 100 times to produce a 100-bit sequence. However, it is also my understanding that a CSPRNG produces an ...
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1answer
146 views
Making PRNG cryptographically secure thru shuffling?
Is it practical to make a PRNG cryptographically secure if I shuffle the randomly generated numbers (say 256-bit) several times before hashing it, even if a hacker knows when I generate the numbers?
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1answer
993 views
Is SHA1 secured enough as a PRNG
I read SHA1 is still a secured hashing function with no collision found as of now. However, it's just a matter of time for someone to come up with such a collision or attack. Therefore, in new ...
