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

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6
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4answers
787 views

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 ...
11
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2answers
5k views

Predicting values from a Linear Congruential Generator

I have learnt that Linear Congruential Random Number Generators are not cryptographically secure - my understanding is that given an LCG of the form: ...
17
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4answers
1k 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. ...
5
votes
2answers
2k views

Are the SHA family hash outputs practically random?

Say I hashed the output from a random number generator (with nonce), would the resulting SHA256 hash be as random as the inputted number? And If I used the first 5 hex characters, and then used the ...
3
votes
1answer
181 views

Detecting steganography in the stream of short messages

I have stream of millions of short n-bit (n<30) messages generated by some random number generator. The source of random number generator is not available to me. I suspect there are messages used ...
8
votes
1answer
148 views

Is CPU timing jitter a usable entropy source?

In some virtualized environments, the only source of entropy available is CPU timing jitter. Can one get enough entropy from this source for practical uses? Also, is this secure against local side-...
8
votes
4answers
932 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 ...
4
votes
1answer
113 views

What is an impure NIST true random number generator?

I'm working on a true random number generator, and I came across this phrase in the American NIST guide, in section 6.4.1 Non-Approved Conditioning Components: The entropy rate provided shall be ...
1
vote
0answers
41 views

how to change math.random() implemented in javascript to securerandom [closed]

In Javscript code in one of our application,I am trying to change Math.random to secure random.I am not sure ,how to change.can anybody help?
8
votes
1answer
385 views

Uniformly distributed secure floating point numbers in [0,1)

Is there any way to generate cryptographically secure uniformly distributed floating point numbers in the interval [0,1)? For example, in Javascript, there is ...
1
vote
1answer
47 views
2
votes
1answer
155 views

Do any (non-hardware) RNGs exist which could be used to create an OTP for crypto purposes?

I've stumbled (jobwise) over a system where small messages (512 Bytes or less) are encrypted and decrypted using a simple XOR using a OTP. That OTP is created using a seed based on the individual user ...
6
votes
2answers
180 views

Hardware Random Numbers - How to convert Voltage signal into binary?

I have a physical unit, e.g. a resistor. I bias it with current and measure the voltage. Let us assume that the fluctuations ($\Delta V=V-<V>$) of this voltage signal are random. Now, $\Delta V$ ...
2
votes
1answer
63 views

Is (1 bit HW signal) XOR (8 bits PRNG output) sufficient for a HWRNG?

This is really a follow up question to a comment made regarding How to roll a HWRNG In the situation of whitening a hardware generated random bit stream, "XORing the two bitstreams should be fine ...
2
votes
4answers
3k views

Is a Mersenne-twister cryptographically secure if I truncate the output?

I want to create an online roulette game. Is it OK if the PRNG is seeded only once, when the user starts the game, or is it recommended to re-seed sometimes during game? Maybe just seeded once a day ...
2
votes
1answer
181 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 ...
11
votes
1answer
91 views

How to tell if a hardware RNG is rigged?

On a related note of building my own RNG, as someone suggested to use several commericial solutions how can I check if it is rigged against me? (although I am still strongly biased to a homebrew ...
2
votes
2answers
120 views

Given PRNG $G(s)$, why is $G(s) || G(s+1)$ not a PRNG?

I have given a pseudorandom Generator $G(s)$, $|s|=n$ whose expansion $l(n)$ is $>2n$. I also know that $G^\prime(s) := G(s_1,\ldots,s_{\lfloor\frac{n}{2}\rfloor})$ is a pseudorandom generator. Now ...
4
votes
0answers
50 views

Reusing same source for single-source randomness extractor

Let $ext$ be a single-source randomness extractor which takes a $d$-bit seed and a $n$-bit source as input and produces a $m$-bit output. Suppose we have a source $X$ with min-entropy $k$. Is it ...
3
votes
2answers
135 views

Will entropy be lost by using a DRBG?

Lets assume we have a DRGB (deterministic random bit generator) which is seeded by a good true RBG (random bit generator). Before any bit has been read from the DRBG, the entropy is clearly the number ...
3
votes
1answer
184 views

CTR DRBG dependent on request size?

I am trying to understand the CTR DRBG specification in NIST SP 800-90A. It seems slightly different to a pure stream cipher in that the key and counter are reset after each generate call using the ...
4
votes
5answers
235 views

How does generating random numbers “remove entropy from your system”?

In a previous question, I quoted the --gen-random entry in the GPG Man Pages. At the end it says: PLEASE, don’t use this command unless you know what you are ...
3
votes
1answer
96 views

gpg --gen-random quality level: is higher “better”?

The GNU Privacy Guard manual pages have this to say about using the gpg --gen-random 0|1|2 count command: Emit count random bytes of the given quality level 0, ...
2
votes
1answer
85 views

Collision likelihood from /dev/urandom for VMs using the same underlying hardware

We have multiple virtual machines sharing the same physical hardware. We use /dev/urandom for session key generation. But a question comes up: if ...
6
votes
1answer
184 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
73 views

Does Mersenne Twister generate homogeneous numbers?

I have been assigned to generate 15000+ homogeneous and uniform random numbers for a work. I have been searching if Mersenne Twister generate homogeneous distribution of numbers but I don't find ...
2
votes
2answers
176 views

Does it necessarily mean that an RSA moduli generated with poor randomness is not random?

In 2012 a group of researchers collected a large amount of RSA moduli and calculated their greatest common divisor in order to find common factors between them. By finding a common factor they could ...
9
votes
2answers
1k views

Does an encrypted random sequence conserve its “randomness”?

If you have a random uniform sequence of bits $A$ generated by a TRNG with good performance of randomness tests (eg Dieharder, NIST, Kolmogorov complexity, chi-square, etc) and perform an encryption (...
9
votes
1answer
761 views

What are the methods to construct a primitive binary nonlinear feedback shift register (NLFSR)?

Given a binary shift register of $n$ bits, a primitive binary nonlinear feedback shift register will generate a sequence with a period of $2^n - 1$. While I am unable to find a paper which directly ...
2
votes
0answers
26 views

Raw /dev/random output for keymat [duplicate]

Noob question: It is my understanding that the raw output from non-blocking /dev/random (where the kernel's entropy_avail estimate is equal to or greater than the number of random bits required) ...
8
votes
3answers
502 views

Why do we require a CSPRNG's output to be indistinguishable from true random?

Everywhere I read, indistinguishability of output from true random is stated as a requirement for CSPRNGs. However nobody bothered to give the rationale for such a strong requirement. Specifically, ...
3
votes
2answers
1k views

Generating unbiased numbers with a biased six sided die?

Eve takes a fair six-sided die and adds some heavy paint to the side of the die with the 6 on it. This results in a biased die that rolls a 6 with probability 2/7, and each other number (1-5) with ...
2
votes
1answer
113 views

Stream Ciphers and cycling questions

For all PRNGs (including CSPRNGs) lets say there is a sequence x, y, z, then when the PRNG cycles back to x, then the sequence following it will be exactly the same as before. Is this true for all ...
1
vote
1answer
170 views

Is it possible to create “non overlapping” RNGs?

For example, let's say I want two cryptographically strong RNGs (R1 and R2). And I want them to have the following property: R1 (resp. R2) will never generate the same random number twice. R1 (resp. ...
2
votes
1answer
64 views

Has there been any research on entropy efficient information-theoretically secure PRNGs?

I have an idea for an research project, but I am first wondering if it has been researched or implemented before. I think I have a way to come up with a set of PRNG algorithms which have the ...
5
votes
4answers
963 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 ...
2
votes
2answers
368 views

Combining a keystream generator with a block cipher

I understand that: A stream cipher's security is diluted if the same key is used more than once. This is fixed by using an additional initialization vector in the keystream's computation. A block ...
4
votes
2answers
869 views

Is it secure to concatenate two 16-bit random numbers into a 32-bit one?

I'm working on a security application for RF modules aimed to protect a communication between an autarkic sensor and a line-powered receiver against MITM (man-in-the-middle attacks). I decided to use ...
4
votes
1answer
730 views

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. ...
18
votes
2answers
4k views

Is HMAC-DRBG or Hash-DRBG stronger?

Out of the two deterministic random bit generators defined in section 10.1 of NIST SP 800-90A (i.e. based on hash functions), which one is cryptographically stronger? Hash-DRBG (Section 10.1.1) HMAC-...
5
votes
1answer
553 views

How to generate unique (random) numbers that can be traced back to a unique source number?

I need to generate unique (random) numbers that I can trace back to a unique source number. For example: source number A can generate numbers A1, A1, A3 .... Am source number B can generate numbers ...
3
votes
2answers
548 views

Whitening and randomness extraction

The Von Neumann randomness extractor is explicitly mentioned in the randomness extractor page of Wikipedia, but strangely enough that page does not contain any reference to whitening the results of an ...
6
votes
3answers
2k 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 ...
2
votes
1answer
66 views

Using Skein as PRNG

I have read that the Skein hash can be used for quite a few different functions, including a PRNG. Would using the 1024 Skein hash to return 16KB of data be appropriate for a PRNG? Or would it only be ...
3
votes
2answers
219 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 ...
2
votes
1answer
426 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 "...
2
votes
1answer
179 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 ...
2
votes
2answers
180 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
2answers
450 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 ...
4
votes
2answers
100 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($K, s$) = HMAC-SHA512$_K$($s$...