creation of (real or pseudo) random numbers (or bits).

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2
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2answers
112 views

Is it okay to include relative time for true random number generation?

Similar questions have been asked regarding use of time in true random number generation, but I'd like to consider using time as just one source of entropy, complementing others. True random number ...
5
votes
3answers
760 views

With a true random number generator at hand, how to implement one-time pad?

I have a Raspberry Pi single-board computer that happened to have an hardware true random number generator, based on some quantum effects on the processor silicon, baked into its BCM2835 chip and I ...
9
votes
3answers
1k views

Webcam random number generator

I have a question about random number generators. I have read from a real random number generator, based on a webcam ("randcam"). My problem is, that I do not really understand how the generation of ...
4
votes
2answers
198 views

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 ...
3
votes
2answers
54 views

A periodic PRNG based on hash function?

I need a PRNG which provides 128 bytes numbers. Let's say that given a symmetric key $K$ and an internal state $s$ I use the PRF HMAC-SHA512 this way: The output is PRNG($K, s$) = ...
7
votes
2answers
438 views

How feasible would it be to generate 300 million public key pairs in 8 hours?

Assume there is a hypothetical situation where one would need to generate hundreds of millions of public key pairs of reasonable strength in a limited time. What would be required in terms of ...
3
votes
3answers
44 views

How does the birthday paradox apply to random keys?

I'm developing a web app where I wish to use pseudorandom keys for items, perhaps akin to Imgur. I was thinking about how many combinations I need to reduce the chance of someone guessing any random ...
-2
votes
1answer
65 views

Shuffleless PRNG function with non-repeating values?

I need a simple PRNG function of type: Integer = PRNG(n, maxval) as I would like to count from 0 to maxval, not in a linear manner, but in a pseudorandom manner where I still use every value, but ...
1
vote
0answers
30 views

Testing PRNG quality from ECC public keys?

Having a large set of ECC public keys $P_i = n_iB$ on a fixed curve $E$ over a prime field, is there a way to determine if coefficients $n_i$ were generated using a bad PRNG? In other words, can a ...
2
votes
1answer
36 views

Prove that H(s) = G(!s) is a CPRNG if G(s) is one

Given a cryptographic pseudo-random number generator $G$, prove that $H$ with $H(s) = G(!s)$ is also a cryptographic pseudo-random number generator. Here $s$ is a binary string; $!s$ is its ...
6
votes
1answer
109 views

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 ...
2
votes
1answer
59 views

How to generate a large random number from smaller ones?

I'm using a function randInt that takes as input two integers as upper and lower bounds (inclusive) and outputs a pseudorandom number in that interval. ...
2
votes
3answers
239 views

How should I interpret this note on diffusion of the internal state of a PRNG?

This question is about Tyche, a non-cryptographic PRNG. While the PRNG is not cryptographic the analysis and this question surely is heavily involved with cryptography, so I think it's on-topic here. ...
3
votes
1answer
100 views

Cryptographic random numbers for key generation

I am trying to understand how a cryptographic library works (for example, one that provides assymetric encryption such as RSA), but I'm running into a few problems about the key-generation. There are ...
1
vote
2answers
118 views

Transforming Gaussian random $[0,1] $ numbers to uniform $[0,255] $

I am not exactly sure if this is for math stackexchange or crypto: A TRNG outputs numbers in $[0,1]$ in a Gaussian distribution. I would like to convert them into uniform random bytes ($[0,255] $) to ...
0
votes
0answers
3 views

How to use /dev/urandom with PHP to get CS random numbers [migrated]

I need to create random integers between the values of 0 and 10,000,000, and I will need several million such numbers. The numbers must be as close to a CSPRNG as possible in that should (for example) ...
0
votes
1answer
66 views

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 ...
1
vote
2answers
111 views

TRNG vs PRNG - Entropy?

How much more entropy gives a Hardware Random Number Generator or True Random Number Generator compared to a Pseudo Random Number Generator? I know it depends on which TRNG is used, but I'm thinking ...
4
votes
1answer
2k views

Who uses the RSA BSAFE library? [duplicate]

Who uses RSA's BSAFE library? Does anyone know what products use it, or have any statistics on how many end users use something that is built on BSAFE? Background: BSAFE is one of the oldest ...
5
votes
1answer
485 views

Can hash functions improve a lousy PRNG?

If I have a poor PRNG, could a cryptographically secure hash function make a better output? Say the PRNG can produce as much numbers as you wish, reasonably random, but not good enough to be used in ...
0
votes
1answer
36 views

What values constitute failing for ENT tests?

The dieharder tests give a clear PASSED, WEAK, etc and I'm wondering what those thresholds ...
2
votes
1answer
70 views

Hash functions to generate one time pad

Newbie question... may be... Stream cypher, will XOR message bits with one time pad bits Suppose I have a pseudo random number generator, like a Mersenne twister or sort of. I could use the ...
0
votes
1answer
101 views

Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22?

I need to use NIST SP 800-22 approved software / hardware to generate RSA key pair. Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22? And how is the SP ...
5
votes
1answer
224 views

Can machine learning analyze random number generator?

I'm studying for random number generators(RNG) and I saw about machine learning a few days ago. So I searched analysis of RNG using machine learning. But I couldn't find such fields. Are there such ...
1
vote
1answer
126 views

How broken is a xor of two multiply with carry generators?

How broken is a xor of two LCGs? How Brittle Are LCG-Cracking Techniques? Based on the above two questions, I have simply one additional question: how broken is a XOR of two 64-bit multiply with ...
2
votes
3answers
105 views

Establishing encryption key using shared secret

I need to establish some security on a network of 8 bit microcontrollers. very limited RAM, CPU and packet sizes. I have zeroed in on a shared secret based scheme. Setting up shared secret is out of ...
1
vote
1answer
58 views

Why in Android kernel CSPRNG state is saved?

I am reading about the security internals of Android. In the book Android Security Internals, in chapter on Cryptographic Providers, there is a para stating: On Android, CSPRNG implementations are ...
6
votes
2answers
114 views

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 ...
2
votes
1answer
83 views

Generating PGP key *without* random generator? (using fixed input only)

I understand why in general, a strong random generator or source of entropy is used when generating PGP keys. However, I have a use case where I want to generate PGP keys deterministically, i.e. ...
4
votes
1answer
587 views

Is it feasible to break Diffie-Hellman key exchange when the implementation uses a poor-quality PRNG?

I've come across an implementation of DH in Java that uses the Random class to generate the secret integer value $a$, as shown in in Wikipedia's description of the ...
0
votes
2answers
69 views

Fortuna: why are source ID and data length added together with entropy data into the pools

Section 9.5.6 of Cryptography Engineering states that The concatenation [of source number, length of data, and data itself] is then appended to the pool. Why are we including source number and ...
0
votes
1answer
43 views

Is randomsound for increasing entropy pool not doing what it is supposed to do?

I am using randomsound because I thought it would be a good idea to inject some additional entropy into the entropy pools of my linux machines (clearly those machines have a corresponding sound card). ...
2
votes
2answers
1k views

Estimating bits of entropy

Best ways to estimate average bits of entropy in a byte stream. I know there are different statistical tests out there (NIST, Dieharder, etc), which all do different ways of analyzing entropy. What ...
0
votes
1answer
47 views

Physical entropy source: How many bits entropy per byte is sufficent?

8 bit / byte would be perfect obviously. head -c 1M /dev/urandom | ent gives ~ 7.9998 bits per byte. Now, if I have a physical entropy source, how much entropy ...
0
votes
0answers
63 views

ElGamal Generator g problem

Having an ElGamal encryption scheme with p=19 which value can not be assigned to g? The answers were : 1,7,11,2 I think you can't assign value 1 to g.
-1
votes
2answers
74 views

Improving on a clocked PRNG

I recently developed a PRNG from scratch with a little inspiration from the initialization function used in the HC stream cipher. The state ($S$) of the basic version is an array of 5 bytes and uses ...
0
votes
0answers
81 views

How many bits of entropy can I expect from /dev/urandom in iOS?

Apple's latest security documentation indicates that it now uses CTR_DRBG for generating pseudo-random numbers (previously Yarrow instead of CTR_DRBG), using "timing variations during boot" and ...
0
votes
0answers
52 views

How to map a handful of numbers in a large range to a much smaller range deterministically without collissions

I want to map a set of long integers (say around 100 different values) that can span the entire 64 bit integer range to a much smaller range such as from 0 to 25000 deterministically with almost zero ...
0
votes
1answer
127 views

Encryption of plain text using stream cipher algorithm

We know that in stream cipher algorithms plain text and generated key are Xored byte by byte. Generated key depends on how much plain text there is and on that basis key will generate and plain text ...
0
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0answers
36 views

How to Exchange Random Coin Flips between Two Untrusted Parties [duplicate]

I'm not sure if this belongs here, but my friend and I were wondering if there was a good algorithm to exchange random coin flips to make some random decision between two untrusted parties without the ...
11
votes
3answers
757 views

How Brittle Are LCG-Cracking Techniques?

There are published techniques for cracking LCGs, but to my eye those techniques seem very brittle — very minor changes can add nonlinearity that renders techniques like the LLL algorithm unusable. ...
4
votes
3answers
518 views

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 ...
5
votes
1answer
319 views

Interpretation of the results of NIST (p)NRG suite

I have problems interpreting the NIST (sts-2.1.2) suite results. After running the statistics with 100 samples (each sample of 1000000 byte length) a new prng i got this result: ...
0
votes
0answers
36 views

Using a Secure RNG in Probabilistic Fair Exchange

I am attempting to implement probabilistic fair exchange described in Probabilistic Non-Repudiation without Trusted Third Party. A secures a message using AES with 512 bit keys (in my ...
5
votes
1answer
187 views

Crack linear congruential generator knowing every other word in sequence

I need to crack one of the example of linear congruential generator. I have $X_{n+1} = (a \cdot X_n + b) \bmod m$ and I know every other word in the output sequence: ..., 3158, ..., 1888, ..., ...
2
votes
2answers
206 views

Is it possible to calculate the 'skeleton key' for DUAL_EC_DRBG? What would it take?

According to Bruce Schneier the constants used in the spec of DUAL_EC_DRBG may be related to a secret set of numbers, that could function as a master key for ...
1
vote
3answers
822 views

Estimating random number entropy for input into 256 bit hash

Assuming a random number generation process outputs lots of numbers between 0-9. First I gathered up a bunch of the numbers, converted them to binary and created a bitmap. Not so random as you can ...
8
votes
4answers
738 views

Creating a small number from a random octet string

I'm trying to figure out the best way to generate a cryptographically secure random number between 0 and 200 (inclusive) from a cryptographically secure random string of bytes (ie. read from ...
0
votes
0answers
26 views

How to check if a sequence is generated by a linear congruential generator? [duplicate]

Assume a linear congruential generator is defined by $x_i=(x_{i-1}\cdot a+c)\bmod m$ and I am given the values $a$, $c$, $m$ and a sequence of numbers starting at the $n$th bit. Can I tell whether ...
7
votes
11answers
2k views

Algorithm: How to use x and y mouse movement co-ordinates to generate random data?

Background: I'm making a program for fun as a learning exercise. I want to generate some actual random key material (not pseudorandom) from a JavaScript program. For my program is just for ...