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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Is using /dev/hwrng for raw key material secure?
Is using /dev/hwrng for raw key material secure (as long as you trust the hardware)?
I tested it using the rngtest tool and it has good output.
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3answers
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How to compute the dataset size required by dieharder tests?
I am trying to use the dieharder random number test suite.
However, this suite requires massive amount of data (this paper claims 228GB for no rewinding for every test) for most of the tests. I'd like ...
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Mismatch between NIST SP800-90A test vectors and CTR_DRBG output
I am testing my Python implementation of NIST SP800-90A CTR_DRBG https://csrc.nist.gov/publications/detail/sp/800-90a/rev-1/final (AES-256, no df) with the CAVP test vectors (https://csrc.nist.gov/...
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2answers
90 views
Rigorous practical pseudorandom generators
It is known that existence of pseudorandom generators (PRGs) is equivalent to the existence of one-way functions. In turn, the latter is an open problem.
I am curious if someone developed kind of &...
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2answers
110 views
Does watching Youtube generate entrophy
Does watching videos (either online videos such as off youtube or saved locally) generate enough (if any) entropy to create secure encryption keys? I understand that some activities such as memory ...
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2answers
236 views
Benchmark for CSPRNG as stream ciphers?
My limitation in my security protocol is that I want my RNG as CSPRNG and I also want it to be super fast.
If I use Salsa20 or ChaCha or AES counter mode, I don't get the desired speed. I want my PRNG ...
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2answers
304 views
Is a LFSR sufficient for post-processing a biased TRNG?
I am building a TRNG on a FPGA based on ring oscillators. I found out that Linear Feedback Shift Registers (LFSRs) are commonly used for the post-processing of TRNGs. Here is my initial design:
Let's ...
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1answer
137 views
Which test suit is better to say if PRNG is CSPRNG:TestU01 or NIST?
Actually my concern is that I am planning to apply xoshiro256+ for implementation of stream cipher https://prng.di.unimi.it/
for my cryptographic application. It passes the BigCrush tests. Will it ...
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Distributed Random Oracle with Verifiable Shares
$Setup$:
Let's assume a quorum of $n$ nodes where each have a secret share $y_i$ from a know and safe leaderless DKG protocol.
Define $\mathcal{L}^i(y_i) = y$ as the lagrange interpolation for $x=0$, ...
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68 views
Is multiple encryption with stream ciphers vulnerable to meet-in-the-middle attacks?
Let's suppose I encrypt something with a stream cipher (CSPRNG) two times using two 256-bit keys and different IVs.
Will I get 512-bit encryption strength?
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2answers
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What is novel about Seedless RNGs?
Seedless Fruit is the Sweetest: Random Number Generation, Revisited introduces a theoretical framework for "seedless" RNGs.
AFAICT, this framework injects entropy directly into the ...
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Why are $\lceil 1/\operatorname{entropy-per-bit} \rceil$ number of bits not sufficient to generate an unbiased bit?
Consider a biased RNG badrand() generating 1 with probability $0.9$ and 0 with probability $...
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1answer
224 views
What is the NIST recommended maximum bias for random number generators?
What is the maximum bias recommended by NIST for random number generators?
This answer says that it is $2^{-64}$.
Is it same for all applications? Does NIST have a publication with more information?
I ...
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3answers
250 views
How to combine $n$ 'less random' bits to generate one 'more random' bit?
Suppose we have a random number generator badrand() generating 1 with probability $0.9$ and 0...
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1answer
59 views
Random number generator in C++ [closed]
I've wrote a simple random number generater in C++.
Simply, I thought, the random things in software. I wrote it based on below:
When an object is created on the stack, its address is random.
The ...
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1answer
209 views
On the initializaton of the “xorwow” PRNG
In the original paper, Marsaglia defines the xorwow() function and gives some example values for the initial state of $x$, $y$, $z$, $v$, $w$ and $d$. But it is not ...
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1answer
72 views
Soundness of Trevisan’s Extractor Against Quantum Side Information
I wonder how sound Trevisan's extractor can be against quantum side information. I checked many papers. And all of these papers were aiming to explain how sound Trevisan's Extractor is against quantum ...
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1answer
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How to get ramdom number between 1 and 2048 from /dev/hwrng?
I am (perhaps naively) evaluating the security considerations of using the following code to create BIP39 seed phrases (on a read-only and offline Raspberry Pi).
Apparently, using ...
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Why VDFs need to be “quickly” verifiable?
I am very new to the topic, I found it out only today afternoon, so forgive the dumbness of the question should that be the case.
I have tried to grasp the rationale of Verifiable Delayed Functions (...
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2answers
160 views
Is it guaranteed that all possible random numbers can be produced?
As far as I know PRGs get an input (seed) and generate a larger output value than the input. Therefore is it possible that some outputs will never be generated? based on the fact that input is smaller ...
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2answers
78 views
How big does M need to be in Blum Blum Shub?
I've read that Blum Blum Shub is a CSPRNG, defined by x_n+1 = x_n^2 mod M. I didn't understand that, and couldn't find any sources on how big should M be.
Are 32 ...
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8answers
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Why do some people believe that humans are “bad at” generating random numbers/characters like this?
I'm not even sure if they are serious, but I've heard many times that some people refuse to not only trust their computer to generate a random string (which is understandable) but also don't trust ...
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1answer
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Could a good PRNG have a long period?
I'm thinking about the evaluation of a cipher or separate cipher round as a PRNG. In general, we can encrypt consecutive natural numbers and check them with some randomness test. But PRNGs don't work ...
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1answer
100 views
Cryptography Engineering - Design Principles and Practical Applications - Chapter 9 Generating Randomness - Section 9.4 The Generator
I'm currently reading "Cryptography Engineering - Design Principles and Practical Applications" written by "Niels Ferguson, Bruce Schneier, Tadayoshi Kohno" published by Wiley in ...
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Using raw encrypted network data for randomness
I've read that encrypted data should be, theoretically, indistinguishable from random data. Using this principle of encryption, could I combine encrypted network traffic streams to generate either a ...
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5answers
4k views
Radioactive Decay, Gaussian or Uniform?
I'm trying to understand the nature of true randomness. I'm building an RNG using a radioactive source. Basically, I'm measuring the time between consecutive decays which in theory should be ...
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1answer
62 views
Can you explain to me how permuted congruential generator XSL-RR-RR works?
I found note about XSL-RR-RR on wikipedia:
https://en.wikipedia.org/wiki/Permuted_congruential_generator
But I don't understand what this means:
count = (int)(x >> 122)
low64 = rotr64((uint64_t)...
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0answers
62 views
Min Entropy per Bit for Trevisan's Extractor/or An Extractor
We know that: trevisan's extractor based on min entropy of the relative system. For trevisan extractor, we need source, seed, min entropy value per bit and error rate for per bit
I have the code for ...
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1answer
45 views
Differences between Extractors and Privacy Amplification for Quantum Random Generators
We know that for the last step of QRNG: we need to separate quantum and classical noises from each other so we use extractors, after extractor we need privacy amplification step. At this point: if ...
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1answer
286 views
Dieharder How can I make my input file suitable for Dieharder?
I created my random numbers and I saved them into a txt file. My input file includes just 0 and 1. Here is the link of my file
And I of course read some answer before asking that question but I could ...
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1answer
78 views
Does piping MT19937 random stream into SHA512 make the state of MT unrecoverable in practice?
It's well known that state of a Mersenne twister is quite easy to recover after you observe enough samples. But what happens if we pipe blocks comming out of MT into SHA512 and give this as output.
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Is a stream cipher and a (cryptographically secure) PRNG nearly the same thing?
If I let the authentification tag aside (which is important), encrypting with AES-GCM and a fixed key and nonce:
...
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1answer
502 views
Introduction to LLL algorithm applied to linear modular inequalities
What is the Lenstra–Lenstra–Lovász lattice basis reduction algorithm about?
How is it applied to solve for $x\pmod m$ a system of modular inequalities $(u_i\,x+v_i\bmod m)<w$ for $0\le i<n$?
I'm ...
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0answers
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How are ChaCha-based ARC4Random CSPRNGs initialized and reseeded?
I'm doing a spare-time project to collect cryptographic algorithms, implement them, and lastly benchmark them.
For the CSPRNG part, I'm evaluating NIST-SP-800-90Ar1 HMAC-DRBG and CTR-DRBG (Hash-DRBG ...
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1answer
51 views
Understanding the Inner State of a RNG
Based on the BSI evaluation criteria for quality of deterministic random number generators:
K4 – It should be impossible, for all practical purposes, for an attacker to calculate, or guess from an ...
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1answer
193 views
Reverse Java seed using outputs generated from nextInt(6)+1
Given a set of numbers within the range of 1-6:
[3,4,3,4,5,6,2,3,1,5,2,3,6,2,2,3,3,6,6,4,5,2,5,3,5,2,4,4,2,6,3,6,1,5,1,3,6,1,1,2,2,4,5,3,1,2,3,4,4,6]
generated using Java's nextInt(6)+1, is it ...
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Fisher Yates on “faulted” random number generator cryptanalysis
For the sake of curiosity and fun, i have implemented a C# program that operate as deck dealer on 40 cards deck (following the Fisher Yates shuffeling algorithm https://en.wikipedia.org/wiki/Fisher%E2%...
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Why is breaking the Blum Blum Shub PRNG not an undecidable problem?
The Blum Blum Schub (BBS) pseudo random number generator (PRNG) is defined inductively by
$$
x_{i+1} = x_i^2 \mod N
$$
to generate the bit sequence $b_0b_1b_2...$ where the bits are taken to be the ...
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1answer
68 views
Is it secure to repeatedly rehash a digest to extend the digest length?
Upon reading through the source code of Rainbow, a post-quantum signature algorithm, I found a hashing function that, using SHA-512, produced a variable length digest.
This was achieved was by ...
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1answer
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What issues are there while using Linux's /dev/urandom for generating cryptographic keys?
As of Linux 5.1 the /dev/random no longer uses the blocking pool. There is a talk about the change on the page Removing the Linux /dev/random blocking pool
I ...
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1answer
59 views
Lehmer random number generator cipher - looking for differentials
I'm looking for differentials in my kind of toy encryption scheme. I can't find any.
Let's consider linear congruential generator:
$X_{k+1} = a \cdot X_{k} \mod 2^{128}$
Such that $a$ is some number ...
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1answer
130 views
The Rationale behind NIST's counter/LFSR recommendation on deterministic IV constructions on SP 800-38D
The NIST has a "SP 800-38D: Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC". This guideline is a base for AES-GCM from definition to security ...
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2answers
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What is the advantage of adversary if the random number repeats?
In proof of CPA-security of encryption scheme $(r, F_k(r)\oplus m )$
where:
$F_k$ is a keyed function
$r\in_R\{0,1\}^n$ is a random number,
on page 85 of Introduction to modern cryptography we have
...
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1answer
67 views
Getting a random number on an STM32L0x1 device for SRP6a
I'm trying to get a random number for a STM32L0x1 MCU to use it in protocol SRP6a.
(I know that there are MCUs with an embedded hardware random number generator. But it would cost twice as much as the ...
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1answer
49 views
Why does l'Ecuyer reject p-values close to 1?
When applying several tests to a given generator, p-values smaller
than 0.01 or larger than 0.99 are often obtained by chance even if the
RNG behaves correctly with respect to these tests (such values ...
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1answer
74 views
On the Acceptability of a Naive Pseudo Random Number Generator
My question is probably both philosophical and technical.
Background
I was developing a CSPRNG, and I needed to shuffle the bits in one step in the middle of the algorithm - any naive shuffle would ...
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3answers
3k views
Why is the output of a True Random Number Generator (TRNG) insecure after it has been compressed?
I came across the following statement regarding true random number generators (TRNG):
A “P1 medium” [AIS31] true random number generator (TRNG) may not be directly used due to cryptographic reasons. ...
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(RNG) For the Middle Square Method, is there a table of periods for various seeds?
I'm interested in the properties of the original middle square method as articulated by John von Neumann and in particular in the relation between seed value and its period length (in cases where the ...
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2answers
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On The Next Bit Test
I would like to know what $O(v(n))$ really means in detailed and simple words please.
I found it everywhere in the literature I am reviewing but I cannot find what the intuition of it (especially if ...
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1answer
99 views
Using AES-CTR as a PRNG
AES-CTR is not considered as a CSPRNG, why ?
Is it unsecure to use it when a password is hashed with Argon2id to produce the seed to generate all random data needed for an end-to-end encyption system ...
