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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Distance between consecutive primes distribution

In several prime generation schemes I saw we pick a random number uniformly at random from a wide range and find the next prime after it. Obviously with such a scheme some primes are more likely than ...
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Can a PRNG be made into a CSPRNG by hashing the outputs?

So I was contemplating this answer to my last question, and it got me thinking: If I understand it right, one of the required properties of a CSPRNG is that it resists leaking information about its ...
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Is the PCG PRNG a CSPRNG, or why not?

Is the PCG family of PRNG algorithms cryptographically secure, and if not, what about them makes them inadequate for that? I have a good enough understanding of the general problem space that if you ...
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1answer
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Faster Shuffling for a Simple Application

Alice, Bob, and Charlie are working on three projects. Alice is the manager. At the beginning of each day, she chooses one project to work on (this choice is based on her preferences and is not ...
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NIST Approved Entropy Source List

Per NIST SP 800-90B – Section 3 – Entropy Source Validation : This Recommendation provides requirements for validating an entropy source at a stated entropy rate. Validation consists of testing by an ...
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NIST test suite for random numbers [closed]

I am using sts-2.1.2 (NIST test suite for random numbers) in Ubuntu 16.04 for testing random numbers and I've installed it successfully. However I don't know how to perform test on random numbers, how ...
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Min Entropy Value for Health Test per NIST 800-90B for 32 bit Noise Source

NIST 800-90B recommends Section 4.4.1 Repetition Count Test & Adaptive Proportion Test for health test on Noise sources. In the equation to calculate the cut-off value C for Repetition Count Test,...
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2answers
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PRNG next bit test

I would like to know whether a specific PRNG satisfy the next-bit test or not. will satisfying all of NIST statistical tests on PRNG guarantees passing the next-bit test? Or is there a specific ...
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1answer
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Does concatinating mutliple digests of hashes from CSRN result in a CSRN?

Kind of a noob question. Suppose; We generate 1,000 cryptographic-ally secure random numbers & store each of them in an array1. For each number in this array1, we take the hash sha256(CSRN) then ...
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The GCD strikes back to RSA in 2019 - Good randomness is the only solution?

When someone collects lots of RSA public modulus, the first thing comes to mind is; $$\text{GCD them all}$$ If you calculate the GCD of two different RSA modulus and if the result is not 1 then you ...
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Perfect shuffle possible with limited raw entropy?

I am trying to shuffle a standard 52-card deck in a perfect way (every outcome should be possible at an equal chance). I am not, at this point, concerned with cryptanalysis attacks against it. I have ...
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The importance of randomness in the creation of a key

Why does it matter what kind of random number generation is used during key generation? E.g. this answer states ...
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1answer
80 views

Creating Random Pad from XORed Sections of Pi

If two strings of equal length from random offsets in Pi were XORed together, would this result in a cryptographically secure random number suitable for use in a one-time pad? If so, would this mean ...
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PRNG XOR Pipeline

For an OTP I need the 'best' random data I can acquire. Please check if my thinking for stacking PRNGs together in a pipeline can only make the output statistically better, never worse?! So take a ...
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3answers
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Should the seed of CSPRNG produce the same random number?

Assume we are designing a CSPRNG to be used in encryption like that used for ECC-based cryptography. Is it required that the seed always produces the same random number always? Or should it be ...
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1answer
86 views

What is the weakpoint of PRNG based encryption? [closed]

Let's say I used this encryption schema: In words instead of images: Hash the encryption key with SHA256 Split it in half, first half use as XOR key for first 128 bit block of plaintext Hash the ...
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1answer
45 views

Is it possible to recover the seed value from a Mersenne Twister PRNG state?

So I know that you can recover the state of a mersenne twister generator by observing a sequence which is long enough. I was wondering if you could be able to recover the actual seed value used or ...
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1answer
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Strong RNG for encryption/authentation algo

I saw in the market several hardware options for creating strong RNG to produce strong KEYS: HSM TPM internal TRNG Intel RDSEED (TRNG)/RDRAND My questions are; What is the strength/entropy ...
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using non prime numbers in Blum Blum Shub or Blum Micali

I would like to use Blum Blum Shub, or Blum Micali methods as random number generators only. I am not interested in their encryption capabilities. I was wondering, if I replaced the prime numbers ...
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Can we use a Cryptographic hash function to generate infinite random numbers?

I have seen that there are PRNG that can generate a specific number of random-numbers. The Mersenne Twister as an example, can generate 2**19937 (if I'm not wrong) but... can we use a cryptographic ...
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Default RNG used by openssl for certificate generation [duplicate]

I have generated a certificate using openssl with the below command. ...
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1answer
82 views

What is the difference between $\in$ and $\in_{\small R}$?

I have a simple question about basic math. When I read different papers bout ABE, I see different methods to choose a random exponent. What is the difference between the following options? Choose a ...
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How is Pre Master Secret related to Client.random or Server.random if DH KEX is RSA

For TLS 1.2 cipher Suite AES256-GCM-SHA384, RSA is KEX(key exchagne algorithm). As per standards of RSA Diffie Hellman KEX, after 'ServerHello' message client gets server certificate and it generates ...
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What are usable entropy sources in a headless machine without /dev/random or any cryptography API?

If I have a headless machine (no mouse movements, no keyboard presses, or user input), without any cryptography CSPRNG APIs, where can I collect entropy from?
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Can the OpenSSL random number generator be considered cryptographically secure? [duplicate]

The OpenSSL Random Number generator documented here uses an OS-provided entropy source coupled with a MD5 hash function. Does it impact the quality of randomness to use a broken cryptographic hash ...
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Any speed up methods for finding the index of a random value produced by the Inversive congruential generator?

The Inversive congruential generator produces random values with: $$x_{n+1} = a\cdot x_{n}^{-1} + b \mod P$$ (special case if $x_n=0$ -> $x_{n+1}=b$) starting with an initial value $x_0$ With well ...
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What is the correct way to choose the start parameters for NIST tests? [duplicate]

I had an idea of creating a pseudo-random binary sequence with that code: ...
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Is it possible to use an algorithm to generate an OTP?

I am a software developer, not a cryptologist. I like the idea of perfect secrecy and would like to use a one-time pad (OTP) to encrypt/decrypt files up to, say, 50Mb. Is there a way that I can use ...
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1answer
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Problem with Hash-DRBG's seedlen values (and others)

In NIST-SP-800-90Ar1, the Hash-DRBG is instantiated with hash functions using strange values for seed length (seedlen) such as 440, 888. How are these values derived? How to derive values for other ...
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NIST DRBG algorithms' optional parameter

As I'm going through NIST-SP-800-90Ar1 spec for DRBG, I found the mention of security_strength in all of the 3 specified construct in the document: Hash_DRBG, HMAC_DRBG, CTR_DRBG. However, they're all ...
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'random' function $r_{n+1} = f(r_n)$, $|\{r_i,\forall i\}|=N$, $r_N = r_1$ where a function $g(r_k)=k$ is harder than in ECC?

Is there a deterministic pseudo random function $f$ with $r_{n+1} = f(r_n)$, $|\{r_i,\forall i\}|=N$, $r_N = r_0$, (for given random initial value $r_0$) where a function which derives the index of a ...
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1answer
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Randomness measure of a sequence over a finite set [duplicate]

If $S$ is a finite set (such as outcomes of a dice). If I have a sequence $x_0 ... x_n$ of elements over $S$, how can I measure randomness quality of such a sequence as compared to measuring quality ...
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Is a number generator based on hashing an incremental string and a seed considered random? Part 2

Sorry I didn't put enough details on my last question, I didn't expect that there is really lots of factors, so most answers were left for speculations. In this question, I will give the scenario I am ...
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Is a number generator based on hashing an incremental string considered random?

Consider the following system 1 - fixed string as a seed, example "something" 2 - concat an increment number "something-1" 3 - hash it, assume it is "9f2054ea4d2c" 4 - take the first 3 digits to ...
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1answer
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“Jitterentropy” vs CPU RDRAND in VeraCrypt 1.24

Veracrypt 1.24 just came out. It uses a true random number generator based on hardware events; namely, on CPU timing jitter, or "Jitterentropy". As an alternative to CPU RDRAND, I am a bit jittery ...
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How can I quickly generate thousands of letters randomly, and strongly mitigate the risk of any compromise?

I want to generate English letters in a truly random manner without resorting to hand-thrown dice, despite their advantages. Rolling dice would be too slow and tiring as I need four thousand letters. ...
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Is there a 'chain-function' which allows computing the value for the index which is next, previous, +/- some constants but has no shortcut for other?

Looking for an algorithm which has a cyclic 'chain'-function which only allows the computation of next, previous element and in addition to that also a shift by a small amount of constants. Example 1 ...
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What PRG expansion factors are safe?

I'm trying to better understand the "cost" of randomness usage/generation in practice. I understand that generally, some (small) amount of "true" randomness is generated, and then a CSPRNG is applied ...
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Why does mt19937 fail the universal test in NIST SP 800-22?

Update: with the help of @SqueamishOssifrage and @PaulUzdak, we discovered that my NIST SP 800-22 has a broken universal test. So this becomes a moot question. Check this report. It seems to sail ...
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Do any block cipher encryption functions (or similar functions) exist which are associative to each other and cyclic?

Most block ciphers encrypt a plaintext deterministically into a ciphertext which allows decryption in the opposite direction. Now, instead of encrypting just one plaintext, I'm looking for a cyclic '...
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1answer
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What is the most secure/reliable CSPRNG currently available? [closed]

In terms of period length, uniformity/distribution, what is the most secure/reliable CSPRNG currently available?
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Help, Feedback and Solutions to a problem on a PoC CSPRNG

Background I do not recommend trying to roll your own crypto. This is just a for-fun PoC, which won't be used in any public or private scenario. I am creating a PoC nearly-true random number ...
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What is the practical impact of using System.Random which is not cryptographically random?

I recently noticed a .NET software using PBKDF to derive an encryption key from a password string. This password string was ...
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1answer
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How can I estimate the amount of entropy (with JavaScript) that I'm seeding a CSPRNG with?

I am trying to determine how much entropy is going into a specific CSPRNG in JavaScript, but I can't seem to find a pure-JS client-side implementation of an entropy estimator. So, I need to find a ...
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Different ways of building a ChaCha20-based RNG

Let's say you're building RNG with ChaCha20 and the fast key erasure technique. There seem to be a few ways to do it. The reference implementation in the SUPERCOP benchmarking toolkit looks like ...
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Efficient way of generating a random number of N (less than 64) bits with exactly M bits equal to one [closed]

Would there be an efficient way to implement a function with the following signature: unsigned long long int random_word(size_t n, size_t m) that would generate ...
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1answer
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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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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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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: ...