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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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
765 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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AES-CTR mode using different key's generated trough PBKDF2 in case at least two IVs repeat
Supposed that a client has AES-128 bit randomly generated static key
The client is using a PBKDF2 in order to to generate a vector(list) of keys i.e. target keys to leverage will be located ...
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34 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
93 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 (...
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1answer
89 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
207 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
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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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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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1answer
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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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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
89 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
93 views
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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1answer
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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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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
98 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
247 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 ...
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2answers
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Encryption using deterministic CSPRNG as secure as CSPRNG
As a beginner it seems that a scheme derived from a CSPRNG should be as secure as that CSPRNG. Is this a correct assumption? Are there restrictions or known special cases? A rough outline would be:
...
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1answer
89 views
Does hashing a PRNG by a cryptographically secure hashing algorithm result in a CSPRNG?
Or specifically, does ChaCha20 hashing of the xoroshiro128+ random number generator result in a cryptographically secure random number generator?
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1answer
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python secrets security evaluation [closed]
The python library secrets gives a title as;
"Secrets - Generate secure random numbers for managing secrets"
and makes a distinction from "random module" by
In particularly, secrets should be ...
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1answer
177 views
How to generate tokens from a secret key?
The problem is simple: I want to be able to spit out 256-bit "tokens" that only I could've produced because I know my secret key $s$, and given any number of these tokens, no one can figure what $s$ ...
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Mersenne Twister's vulnerabilty with small-size distributions
C++ rookie here, trying to wrap his head around (CS)PRNGs.
I (assume that I) already understand the concept of the Mersenne Twister being "broken" (i.e. not cryptographically secure) due to its ...
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1answer
55 views
Randomizing Prime Field Elements
I need my code to generate random elements from $GF(p)$ ($F_p$ or $Z_p$, if you will).
The Crypto API I have available provides one with random bit strings. To tailor that to my needs, I can think of ...
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1answer
53 views
adaptation of NIST sp800-22 for short sequences
I would like to ask about the NIST test suite for randomness evaluation. The test suite consists of 15 subtests which evaluate the particular property of the sequence.
In fact, each test has an ...
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1answer
191 views
HMAC-SHA512 output randomness?
This is regarding an online roulette game that claims to be fair. Here is the explanation:
Two strings are created:
...
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2answers
170 views
How is a ciphertext encrypted using random numbers decrypted using a symmetric key algorithm
We use true random number generators as a source of keys for encryption. What I can not wrap my head around is: How is this cipher text decrypted in case of symmetric key algorithm as we need the same ...
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0answers
33 views
ZK-proof of usage in a seed of CSPRNG
Assume a Player chooses a seed $s$ and he wants to prove that he uses it as a seed to CSPRNG function, where the seed is not public.
How can he prove it?
Thanks.
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0answers
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Can you rely on the permutation of a ciphertext for secrecy?
Say you have a message and you run it through an all-or-nothing transform. A transform that requires every single block in the correct order in order to recover any data. Each block is ...
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1answer
103 views
repeatedly hashing result and using reverse sequence as RNG secure?
I want to have a source of randomness for which:
no one but me can predict the next number in the sequence.
I know the entire sequence in advance, but I have no way of manipulating it once the first ...
3
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1answer
98 views
Cryptanalysis on affine like matrix based strange cryptographic scheme [closed]
This is a garage made encryption scheme provided as cryptanalysis practice during 34C3 CTF.
The challenge is done under the following assumptions
All Mersenne twister instances are MT19937 64bit ...
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1answer
85 views
LFS Kolmogorov Randomness
Consider following LFS register (where + denotes addition modulo 2)
I have found the output sequence as 1,0,1,1.
I know that The K(s) of a string s is defined as the length of the shortest computer ...
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1answer
241 views
Identifying the type of algorithm for a PRNG that uses modular multiplication and addition
GNU libc uses the following pseudo-random number generator: $$(\mathit{state} \times 1,103,515,245) + 12,345 \pmod {2^{31}}$$ where state is the result of the previous call to the generator.
My ...
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5answers
171 views
Pseudorandom number generator for which it is impossible to deduce the seed
I'm looking for an RNG that in the case that an attacker would get all or part (most likely part) of the pseudorandom data, there will be no way for them to deduce the original seed more efficiently ...
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2answers
154 views
Is this a good way extracting randomness from some physical process?
Let's say the system has a hardware randomness generator, generating random numbers using a proven truly random process. The distribution of the numbers though, is unknown.
Assume the randomness ...
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1answer
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Why does BCRYPT_RNG_DUAL_EC_ALGORITHM get removed from CNG API on Windows 10?
On article at => Microsoft Docs
CNG Algorithm Identifiers
I notice that BCRYPT_RNG_DUAL_EC_ALGORITHM is now removed since Windows 10.
Beginning with Windows ...
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Geometry of the outputs of linear congruential random number generators
I learned that possible $m$ long sequences produced by linear congruential random number generators(of the form $r_{i+1}\equiv ar_i+b \mod n$) fall on hyperplanes. Using this fact I have come to think ...
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0answers
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What is the fastest way to generate truly random one time pad without electrical or any other complicated device?
I want to generate truly random one time pad as fast as possible but without the use of any electrical or any other complicated device. What is the fastest way to do that?
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3answers
155 views
Usage and limitations of sponge functions for PRNG
This HRNG uses SHA3 as a sponge function (in its device driver) to inflate ots raw source output to many MByte/s. They compare this output rate to the output of other HRNG which don't use a sponge ...
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0answers
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How Are Linear Congruential Generator Multipliers Chosen?
There are several numbers that keep coming up when looking at certain random number generators, for example 6364136223846793005 is used in newer pcg-family algorithms and seems to draw it from ...
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0answers
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Question on inputs of PRFs and HKDF KDF
I've read a lot of information about PRNGs, PRFs and KDFs. As far as I know:
PRNG: The seed for the PRNG must be a uniform string. It transforms a short real uniform string into some bits of pseudo-...
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3answers
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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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5answers
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Why are PRNG in programming languages not cryptographically secure by default?
In most programming languages, there is a module or function in the stdlib for creating random output like random.random() in Python.
Because those functions use a ...
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1answer
273 views
Any concrete examples of the use of NIST Special Publication 800-90B?
This question relates to NIST Special Publication 800-90B, Recommendation for the Entropy Sources used for Random Bit Generation. A copy is available here.
Can anyone supply a pointer to any ...
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3answers
408 views
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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2answers
92 views
Figure out algorithm to numeric key generator with one known input and output
I have a software program running on a piece of hardware. To access a specific functionality it runs a challenge-response-like authentication, that is it generates a numerical 4-digit PIN and expects ...
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2answers
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Is a tree of CSPRNGs secure?
Given two CSPRNGs $A$ and $B$ (of possibly the same family/algorithm), where $A$ is properly seeded from a high-entropy source, can $A$ be used to seed $B$ without compromising the security of either? ...
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1answer
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In coin flipping protocols, why aborting is allowed, and why the non-aborting party flips a coin at the end?
To convey how an adversary can bias the coin, most often a simple commitment-based two party coin-tossing protocol is given, as in [1]:
Alice sends Bob the commitment $c = commit(x)$
Bob sends Alice ...
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1answer
297 views
ECDSA vulnerability related to recovering private key using same r
I'm considering this for bitcoin transaction as it uses ECDSA so if the signer generates two signatures suppose s1 and s2.
where:
I get it that any attacker who have s1 and s2 can recover its private ...
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3answers
1k views
Encrypting RNG output
Under the following premise:
I need to generate multiple symmetric keys;
I cannot be sure about the quality of local system RNG;
I already have a strong key K (generated by other means / elsewhere).
...
