Questions tagged [randomness]

Usage of randomness (i.e. non-predictable data, usually in the form of bits or numbers) for cryptographic purposes.

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Generating UUID from Keccak-256 hash

Is generating Keccak-256 hashes with timestamp + nonce (ensured to be unique for each run), and taking its most significant 16 bytes sufficient to generate random V4 UUIDs? Obviously the 13th hex ...
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Random Bit Generation [closed]

I am new to cryptography , and I am trying to recreate the RSA 1024 bit encryption algorithm from scratch.I was wondering how I could make a CSPRNG from scratch to generate 512 bit primes for RSA. ...
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The security of using a digital signature scheme twice with randomness

Suppose $\Pi=(Gen,Sign,Vrfy)$ is a secure signature scheme, is the following signature scheme $\Pi'$ secure? $Gen'$: The same as $Gen$, output public-private key pair $pk,sk$ on input $1^n$ $Sign'$: ...
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NIST STS randomness testing inconsistent results

I have generated the nine datasets according to this document for AES-128 and testing these for randomness using NIST STS. However, the results are inconsistent. Sometimes there appear a * in the ...
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Why cant you use randomness to seed more randomness?

If I have 256 bits of handwavium "perfectly random data" and I hash these 256 bits of data with a secure hash function (possibly SHA-256). Could the resulting hash be considered "...
3 votes
1 answer
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What is a "set synchronized CSPRNG"?

I'm looking to implement a performant revocation method for JWTs. I'm reading a paper, in which the following section's second paragraph states: If we use the client hashing approach described ...
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Is it possible to compress a random sequence with high entropy?

I have an algorithm that generates a pseudorandom sequence with a length of 100k and high entropy. I would like to check the quality of its randomness. So, I used a popular software program to ...
1 vote
4 answers
467 views

Any famous approach for analyzing the randomness of data?

I'm writing a function that will allow me to analyze the randomness of some input data and return some stats about the probability of this data to be random. Obviously it should be based on two things:...
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2 answers
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Random numbers used for ECC Diffie-Hellman

As the first step for generating a secret DH key a uniformly distributed random number $k$ must be generated, which is used to calculate the $k$-th exponent of the basepoint $A$. Depending on the ...
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Indistinguishability obfuscation and PRFs

Consider a family of pseudorandom functions $F$, each member $f_k$ of this family is indexed by a key $k$. It is true, due to a result by Barak et al, that black box obfuscation is not possible for a ...
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If G is a PRG, is G' necessarily a PRG?

Given: A function $$G: \{0,1\}^{3n} \to \{0,1\}^{6n}$$ which is known to be a secure Pseudorandom Generator (PRG). A derived function $$G'(x_1 \| x_2) = G_b(x_1\|0^n\|x_2), \text{ where } x_1, x_2 \...
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RSA random key generation [duplicate]

How RSA keys are tested for primality if they are random generated? I imagine this could be time consuming task.
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A question about "attacks on MAC key space"

At page 336 in "Handbook of Applied Cryptography - Menezes", I see the sentence For $n$-bit MAC with $t$-bit key space this requires $2^t$ MAC operations, after which one expects $1+2^{(t-n)...
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Can this algorithm be called a RNG?

So I developed this algorithm as RNG, although it looks random to me, I wanted to know the opinion of more experienced persons in the topic. ...
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From Entropy's perspective how Encryption affects a Message?

How Ciphers, specifically, Substitution Ciphers and Transposition Ciphers manipulate the Entropy of Plaintext w/wo the aid of Entropy Source? Reversely, how Decryption manipulates the entropy of ...
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Two-party randomness for KEM

As indicated in an earlier Q / A, KEM's do not necessarily directly encrypt a pre-generated random value. However, it is clear that some KEM's do actually do this, with RSA-KEM being an obvious ...
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1 answer
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NIST random number tests report

I am using the NIST test suite to test random binary numbers. when I tried it for data.pi, the generated report has some items that can not be interpreted. for example, the coeffecients named C0~C10. ...
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Deterministically secure PRG from deterministically secure OWF

Consider the construction of "A Pseudorandom Generator from any One-way Function" [HILL99] in Hastad et al. One way to proof pseudorandomness of this construction is by contradiction. That ...
4 votes
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What are the state-of-the-art TRNGs today?

How fast are the fastest ones? Which ones have the most entropy? Which ones are the most practical ones? I tried looking for answers on Wikipedia and also, I tried reading papers, but I am couldn’t ...
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Is it valid to transform the tested sample file and re-test, rather than invent additional randomness tests?

I'm enhancing the venerable ent randomness test suite. And I came across this idea in On Independence and Sensitivity of Statistical Randomness Tests. "To ...
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1 answer
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Does game-theoretical fairness work in when the goal of one party is randomness

When we take the coin flip in Blum's algorithm in "Coin flipping by telephone a protocol for solving impossible problems", where Alice and Bob both want ownership over the same car, then one ...
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Does randomization make a big difference in the output of the BKZ algorithm?

We all know that block Korkine-Zolotarev (BKZ) algorithm is essentially a deterministic lattice reduction algorithm. However, in the actual implementation, the BKZ algorithm contains some ...
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Can someone give a comprehensive guide on how to run NIST SP 800 90B entropy assessment c code in windows? [closed]

I am trying to run the github code in windows 11. I don't know what all I need to install in my laptop to run the C++ code. It would be a great help if someone can point out the steps to run the code.
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A HRNG that is NIST 800-90 compliant is not suitable for use for OTP generation right?

A HRNG that is NIST 800-90 compliant must use a DRBG in some way regardless of whether it adheres to a RBG1, RBG2 RBG3(XOR), or RBG3(RS) construction. This violates the requirement that the OTP is ...
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Why does NIST SP 800-90C RBG3 construction require XOR or reseeding a DRBG with a physical entropy source to produce full entropy?

NIST 800-90C defines 3 classes of random bit generation (RBG) constructions: RBG1, RBG2 and RBG3. All constructions must include a DRBG from NIST SP 800-90A. The particular construction in question is ...
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If we supply a random uuid4 hashed salt to Hashid, will it be considered secure?

Ideally, Hashids -: https://pypi.org/project/hashID/ are considered insecure and it is recommended that we should not use them for any sensitive functions. Though, is a HashId considered secure if we ...
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Why is decryption algorithm usyally deterministic?

For security against Chosen Plaintext Attack (CPA), we need randomized algorithms for encryption. But in some schemes (maybe almost all of them) take decryption algorithm deterministic. This procedure ...
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Good entropy from entropy test (90B) but still fail NIST800-22

I designed my TRNG with FPGA. My TRNG has a good entropy performance with a value of 0.99x over several test times. But for the NIST800-22, during several run times, sometimes my sequence passes all ...
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Does quantum-sourced randomness allow a potential random oracle instantiation?

My question is essentially the same as this one. The random oracle is a black box that does two things. Maintain a lookup table for any query that has already been asked. For all new queries, toss a ...
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Are Universally Unique Lexicographically Sortable Identifiers (ULIDs) safe to use as a session id?

The spec ( https://github.com/ulid/spec which is not a real standard ) explains that there are 80 random bits in an ULID. UUIDv4 is better from a security aspect, as it has 122 bits for randomness. ...
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Randomness and authentication on short value outputs (48 bits)

I want to implement a client that generates random 48-bit values and send them as broadcast messages. We assume also there is a legitimate receiver getting those values (so, there is some sort of pre-...
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1 answer
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Threshold Paillier encryption key generation time

I have used the threshold version of Paillier encryption without a trusted dealer in an application. I have tested the key generation phase with different security key sizes such as 80, 512, 1024, and ...
2 votes
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Is there any secure deterministic two-party computation protocol?

The notion of security considered here is privacy. Is there a secure two-party protocol does not rely on randomness at all when considering passive adversaries (or active adversaries)? If the answer ...
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Can the last n bitcoin blocks (including transactions) be reliable enough to be used as a seed for a PRNG or an input to a crypto hash-function?

Suggested by u/HolgerBier on reddit Is it unpredictable enough or too difficult to manipulate (as in more than a few hundred million USD) to have a sequence of blocks?
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What are some ways to produce a pre-determined sequence of a large number of dice rolls? [closed]

What are some ways to produce a pre-determined sequence of a large number of dice rolls (on the order of 100-1000 times) using biased dice or a biased human roller given the constraints that multiple ...
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1 answer
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Randomness of recursive sequence generation

How good from a randomness point of view are recursively generated sequences using good encryption algorithms? Let us say I take AES128 which generates good random sequences of outputs for counter ...
4 votes
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Use of scrambler LFSR for randomness extraction of semi-random source

I am using a linear feedback shift register (LFSR) in a scrambler configuration as a randomness extractor for a weakly random source. This source is semi-random (aka. Santha-Vazirani source): the bits ...
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Is a pseudorandom function (PRF) also a one-way function (OWF)? If yes, how can we proof that a PRF $f_k$ is a OWF? If no, what is the closest work?

Let $f_k$ be a PRF. We claim that $f_k$ is a OWF. PROOF let $f_k$ is not a OWF, there exists a $PPT$ algorithm $A$ that can invert $f_k$ with non-negligible advantage. Even if we know the input $x$ ...
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1 answer
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Walsh-Hadamard transform in randomness testing

I am working on using the Hadamard transform as a way to map randomly generated values and then apply statistical tests as defined by Nist or other institutions. One resource online I found ...
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1 answer
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Frequency Monobits Test

As detailed in the paper Statistical test suite for random and pseudorandom number generators for cryptographic applications by NIST, the first test is given as a basic significance test, it uses a ...
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2 answers
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What is entropy?

We discuss a lot of topics and use measures of entropy to determine how difficult it is for an attacker to be successful. What does entropy mean in the context of cryptography? How is entropy ...
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Runs and Autocorrelation test

I have the book "Handbook of applied cryptography". In there we have example for random tests. I have bits sequence ...
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8 answers
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How to generate random numbers within a range (0,n) from random bits?

What is a good method to generate random numbers between 0 and n from random bits? For example, I have a one million random bits generated according to NIST SP 800 90 publications. Now I need to ...
2 votes
2 answers
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A problem about matrix

I have an idea but I don't know if it will work. For the appropriate $p$ it is easy to find $n$ linearly independent $x_i$. Then we compute the inner product between the $x_i$. I think the information ...
4 votes
2 answers
203 views

Paillier cryptosystem break with random number

In the Paillier cryptosystem we choose $n=p\,q$ where $p$ and $q$ are primes, $g=n+1$, $\lambda=\phi(n)$, $\mu=\lambda^{-1}\bmod n$. The public key is: $(n,g)$. The private key is: $(\lambda,\mu)$. ...
6 votes
1 answer
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How can 4 users generate a provable fair random number?

The past few weeks I have been trying to solve a difficult problem. I have asked some cryptography experts but unfortunately they had no clue on how to solve the problem. The situation is as follows, ...
5 votes
2 answers
410 views

DDH hardness with shared public parameters

DDH is believed hard for subgroup of $ℤ^*_p$ with order $q=(p-1)/2$ when $p$ is a safe prime chosen randomly. What if $p$ isn't random: When parameters are shared, $p$ mightn't have been chosen ...
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How bad are human-generated random numbers really (One Time Pad)?

This is a pretty open question, so I'm mostly looking for gut reactions from experts more educated than I. Given these assumptions which are easy to verify with a quick Google search: One Time Pads ...
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ECDSA security proof in random oracle [duplicate]

I need to know if there is a security proof for ECDSA in the Random Oracle model?
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1 answer
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How to interpret a formula from the handbook of applied cryptography

In the handbook of applied cryptography, we can find the following formula for testing PRNG. My question is what does mean 2 in the upper index of the ...

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