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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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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If I am about to generate one-time pad, where should I generate my pads from?

If I want to generate a few one-time pads, is it OK to just read required number of bytes from /dev/urandom without weakening information-theoretical security?
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Why do we use pseudo random PRNG in cryptographic applications instead of true random number TRNG

Cryptographic applications use deterministic algorithm for random number generation that are not statistically random but they appears to be random. Why do cryptographic applications use PRNGa ...
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Random number generator issue

I wrote a litte random generator using a geiger tube. I use a 16bit timer that overflows every ~1ms; when i get a reading form the geiger (~36count/minute), i save the current timer value as "random ...
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Are there flaws in (cryptographic) science/engineering/software/research due to pseudo random generators?

I am trying to see if there were any incidents in the past where using PRNG or not actual random scheme leaded to wrong conclusion in research. For example, a lot of fields today use simulations to ...
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Is Curve25519 vulnerable to private key exposure in the case of a bad RNG?

I'm really excited by what I've learned of advancements in elliptic-curve cryptography. Curve25519 seems to be a great choice at this point in time, but if I recall correctly, some elliptic curve ...
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Is ISAAC considered secure as a cryptographic random number generator?

The ISAAC site claims it is secure, but I wasn't aware of any trusted 3rd party sources that verified its security.
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Differences between methods of hardware random number generators

I'm reading about various hardware random number generators which - among others - implement the following approaches: Analog-to-digital converter noise Johnson–Nyquist noise Reverse biased ...
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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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True random numbers generated by sensors

Is using sensor raw data a good way of generating true random numbers? I mean using an IPhone's gyro/accelerometer raw output as a base for generating an array of true random numbers.
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When is an RNG a CSPRNG, a CSRNG, or a TRNG?

In a recent answer to a question about CSPRNGs, it was stated that… Nondeterministic algorithms where there is no such requirement, and ideally could be replaced by a true random generator. Example: ...
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Can I break a random number into two smaller vectors and consider them as two random numbers?

I have a cryptographically secured RNG that uses a recommended block cipher to generate the random number. As its output, I receive the random number which is very large, but the application requires ...
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Generating a random number using a quantum computer

I have been looking into the creation of truly random numbers using a quantum computer, but I have been having trouble with finding resources on this problem. Is it possible to create a truly random ...
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Does a hash function in chaining mode or in counter mode make a better pseudo-random number generator?

I have two pseudorandom generators: $f_1$ takes a random seed $l_0||r_0$ $\in \{0,1\}^{160}$ as input and outputs $r_1||r_2|| \dots ||r_k$, where $l_i||r_i = \operatorname{SHA-1}(l_{i-1}||r_{i-1})$ ...
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Perform ENT / Dieharder on raw entropy or on whitenened entropy?

In this question about hardware random number generator, a discussion about the following question has been started: In order to test RNG's and entropy's quality, should test suites like ENT and ...
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Can it ever be impossible to invert a PRNG?

I've read about the possibility of inverting the Mersenne Twister after 624 numbers of output. 624 matches the state size of my implementation of the Twister. Coincidence? If the generator only ...
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Why does anyone use elliptic curves for a CSPRNG?

I saw Martijn Grooten's talk on elliptic curves at BSides London this year, and it helped me understand how elliptic curve crypto works, especially in the case of Diffie-Hellman (ECDH). He also ...
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What quality of randomness is needed for randomized side channel countermeasures?

Using per-operation randomness is a popular and effective way to protect cryptographic implementations against side-channel attacks, e.g. using Shuffling (randomizing the processing order eg for AES ...
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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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Diode vs quantum computer

Consider everyone's favourite pseudo random number generator, RANDU where V is the output of any successive iteration. $$ V_{j+1} = 65539 \cdot V_j \; mod \; 2^{31} $$ I've purposefully chosen ...
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Generating random non-repeating numbers from a small group

I read this Q&A which gave a clever solution: feed an incrementing index into a block key cipher as a way of producing non-repeating random numbers. The problem is the block size of all the good ...
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Are there any practical ways to transfer random data securely?

The owner of the random.org service recommends that you do not use randomly generated numbers from their website in cryptographic keys. This makes sense, but it got me wondering. Is it possible to ...
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How to find generator $g$ in a cyclic group?

As generator $g$ is used in DH how do you find a combination of prime $p$ and $g$? eg: if we choose $p=23$ and its generator is $7$ (given in the book) how do we find the generator?
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How to analyze the off-by-one error's impact on the entropy of the result?

I'm reading Jean-Philippe Aumasson's book Serious Cryptography to learn more about cryptography. On page 37, the author gives an example of Cryptocat's off-by-one error in its PRNG implementation in ...
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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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How to determine the next number from java's Random method [closed]

I understand a little how Java's Random class works. I have two random numbers output from calls to nextInt() from a ...
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How can a poor RNG impact security?

I have read this article and I do somehow "understand" that the reduction of entropy makes it easier to guess. But how exactly can the security be reduced by that? Can you give a concrete scenario, ...
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Good enough deterministic PRNG based on hashes

Lets say I have a seed named iv which has a decent amount of entropy. Are there any glaring issues with the following? First 64 bytes are generated by SHA512(iv) Next 64 bytes are generated by ...
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New PRG from old

Is the following statement true: If $G: \{0,1\}^k \to \{0,1\}^n$ is a PRG, then so is $G':\{0,1\}^{k+l} \to \{0,1\}^{n+l}$ defined by $$G'(x||x')=G(x)||x'$$ where $x \in \{0,1\}^k$ and $x' \in \...
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Are my random numbers really “bad” or is that a statistical effect which “must” happen from time to time?

My software uses a TRNG (entropy source) which is part of an MCU. A check of random numbers generated by my software, carried out by a testing authority revealed a problem, which I have to examine ...
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What weaknesses in Hash_DRBG did NIST find and fix?

Matthew Green states in the Practical Kleptography presentation (video, at about 12:15) that Hash_DRBG (from SP800-90A) as originally proposed by NSA had potentially exploitable flaws or bugs and that ...
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How do I produce a stream of secure random numbers from AES-Counter mode?

I have just made my own program to encipher, using AES in counter mode, and have validated it using NIST data. So I know I have done it properly. I have read that AES-CTR can produce a stream of ...
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RSA random prime generator

What is the current standard of random bit generators? RSA relies on two large prime numbers, and I am wondering what is the algorithm used to generate such numbers?
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Is SHA-1 secure when used to implement a PRNG

I read SHA-1 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 ...
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Can I create a random access CSPRNG from a hash?

Can I use a keyed hash of a counter as a secure CSPRNG? E.g. 4th random block is Hash(4, seed) If not, what are the possible attacks?
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LFSR get output from characteristic polynomial?

Say you have a characteristic polynomial of an LFSR: $$f(X) = X^4 + X^3 + 1$$ How can I use this function f to get the output of the LFSR, given some initial state? Obviously I can create the LFSR ...
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Is this a good entropy collector and whitening technique?

I'm just reviewing a program someone wrote to provide high quality random data using an entropy collector and a hash based whitening technique. I'll try summarize the process: Collect entropy from ...
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Why aren't stream ciphers extremely secure?

The way I understand it, stream ciphers are pretty much one time pads off-sourced to a PRNG (the seed is the key that generates the fake one time pad). So why not just use one or more CSPRNGs (...
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Are factorization algorithms parallelizable?

I was reading about the Blum-Blum-Shub random number generator, and its security depends on the hardness of factoring very large numbers (like many things in crypto do). I'm just wondering, if I have ...
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Is there a secure source of entropy on a typical microcontroller?

On a device that does not have a hardware RNG, what is the best source for entropy? Some options and pitfalls floating around: Use the ADC to read something analog: can become deterministic if ...
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Hash functions to generate a one-time pad

Maybe this is a newbie question: Stream cypher, will XOR message bits with one-time pad bits. Suppose I have a pseudorandom number generator, like a Mersenne Twister or something similar. I could use ...
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How can a block cipher in counter mode be a reasonable PRNG when it's a PRP?

Wikipedia claims: A secure block cipher can be converted into a CSPRNG by running it in counter mode. This is done by choosing a random key and encrypting a 0, then encrypting a 1, then encrypting ...
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True Random Number Generator by milliseconds per keystroke (TRNG-Kms)

The simplest way to generate truly random numbers for OTP keys is to measure the time in milliseconds between each keystroke on a keyboard. The randomness depends on the user typing in various speeds. ...
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Secure AES Key Generation via Salsa20?

I am not rolling my own crypto or anything - just trying to learn about the Dos and Don'ts of cryptography: specifically about AES encryption and ways to generate keys for that. As far as I've ...
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How can I extract randomness from a JPEG file?

In a previous question I asked if (and why) BlueRand can or cannot be considered as a TRNG. Established that it's not a TRNG (due to the reasons explained by some users in the previous question), ...
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How to convert AES to a PRNG in order to run NIST Statistical Test Suite?

I want to run statistical tests on my implementation of AES. How should I convert it into a PRNG? Is there a standard way to go about doing this? I could not find much information about this although ...
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Formal relationship between encryption and random number generators?

Cryptographically secure random number generators seem to have similar properties to symmetric encryption: initial seed is permuted to produce a random numbers (key and ciphertext) given the seed, ...
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Unit testing a library RNG and its seeding for practical security

Suppose I have a cryptography library that provides me with a black-box random number generator that is supposed to be suitable for long-lived key generation. (Under the hood it may be assumed to use ...
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Proof that Alternating Step Generator and modifed ASG' have equivalent security?

The Alternating Step Generator (ASG) is a PRNG combining 3 LFSRs. Output of the ASG is the XOR of the output of two clock-gated LFSRs. At each step, a single one of these LFSRs is clocked, according ...
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How often to reseed the NIST CTR_DRBG with AES256_CTR

Even at a high consumption rate of 100,000 generations per second, it would take decades to exhaust the NIST recommended reseed interval of 2**48 invocations of DRBG _generate(). Should one even care ...

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