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

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2answers
136 views

CSPRNG that cannot be used as random extractor

Are there any specific CSPRNG's that cannot be used as randomness extractor within a TRNG? In other words, can you simply provide enough entropy gathered from a good entropy source as seed in any ...
3
votes
2answers
351 views

Map Bytes to Number

Using node.js crypto library I can generate cryptographically strong bytes. How can I use this to generate a random number between 0 and 9999 (both inclusive)?
3
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4answers
866 views

random number generator 10-side dice alternative

A lot of sites (e.g. Dirk Rijmenants') refer to 10-side dice to generate random number for one-time-pad. I was thinking about new ways to generate random numbers, letters and passwords. here what I ...
3
votes
2answers
269 views

How to generate a random integer in interval $[1, 2^n-1]$ from random integer in interval $[0, 2^n-1]$?

For a project I am working on, I have access to a CSPRNG that outputs a random integer in the interval $[0, 2^n-1]$ for any integer $n$ greater than 0. I cannot use the zero values, so I have my RNG ...
3
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2answers
1k views

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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1answer
735 views

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 ...
3
votes
2answers
313 views

Breaking a PRNG Scheme

Assume the following scheme for a PRNG generating decimals in [0,100) Given a message and a key, compute tag := HMAC512(message, key). Take the first 5 hexadecimal characters of the tag. If the ...
3
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1answer
128 views

Potential vulnerability in DH key selection - am I understanding this right?

I'm reading through a DH implementation, and I think I found a potential hole. Public $p$ and $g$ values are properly selected. A candidate secret value $\bar a$ is pseudo-randomly selected such ...
3
votes
1answer
501 views

Are there secure stream ciphers that cannot be parallelized?

Are there any stream ciphers (or a deterministic random number generators, that should work as well I guess?) that cannot be parallelized? So for example if I seed it with a specific value, and then ...
3
votes
1answer
307 views

Predicting Java's PRNG using partial output

I have a program (a game) that uses Java's nextInt function with parameter 0x10000 to get a random 16-bit number. Java's ...
3
votes
1answer
352 views

Which PRNG security requirements do I need for key generation

Do I need to worry about "predictability" an an allegedly secure CSPRNG if I am just using it to generate key material from time to time? Suppose that for some odd reason, I am less trustful today ...
3
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2answers
59 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($K, s$) = ...
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3answers
46 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 ...
3
votes
1answer
299 views

Unpredictability vs randomness

I'm experimenting with creating an entropy source for an environment where I have no hardware available and the language is very high level (executed in a virtual machine). I know it's not a good idea ...
3
votes
1answer
193 views

Does changing the random number selected for each message increase security in Schnorr's scheme?

I was reading about Schnorr's scheme and in that for signing the signer generates a random number and continues with his operation. I am trying to implement this in a scenario where the signature ...
3
votes
1answer
239 views

Seed a PRNG with random data and a password

I'd like to combine a random key file with a password to generate a secure seed for a CSPRNG. The key file is assumed to have very high entropy, but the password will be whatever the user provides. ...
3
votes
1answer
195 views

Does hash_df use binary or an ASCII hexadecimal representation for numbers to be passed to the hash function?

I'm implementing the HASH_DRBG algorithm. As per NIST-SP800 90 document for HASH DRBG Generation, section 10.4.1 "Derivation Function Using a Hash Function (Hash_df)", the Hash_df algorithm contains ...
3
votes
1answer
440 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. ...
3
votes
2answers
813 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
901 views

Are there any Javascript CSPRNGs? [closed]

I'm writing some software that requires the use of a CSPRNG with javascript for use in the browser and I'm wondering what libraries are available. Crypto-js doesn't seem to have a CSPRNG I can ...
3
votes
1answer
940 views

RSA key pair generation using PRNG with same seed

I see a lot of Q/A where persons are trying to generate a specific key pair using static data such as a password. Now say we use a known PRNG (dangerous assumption), seeded with a the data as a static ...
3
votes
2answers
729 views

Using an RSA private key simultanously as an AES encryption key to generate random numbers?

Currently I'm implementing a PRNG for an embedded system. Using the RFC 4086 I've decided to use the X9.17 - to be more specific the successor X9.31- standard to implement my PRNG. X9.17 uses DES, but ...
3
votes
1answer
104 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 ...
3
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1answer
3k views

Generating a secure random number in javascript

What I am trying to do is generate a large (4096bit) random number in JavaScript that is cryptographically safe to use. My approach is the following: I am creating a ...
3
votes
0answers
279 views

Entropy of Androids motion-sensor data

My app on Android uses the built-in motion sensors to collect seed-data for the PRNG (java.security.SecureRandom) that is later to be used for key-generation. The user is told to shake the device so ...
3
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2answers
171 views

Alternative sources of random numbers

Considering that algorithmic methods for generating unpredictable streams are hard to come by, I've wondered if any of these potential sources are good for making keys, seeds, and the like: stocks, ...
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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 ...
2
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2answers
135 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 ...
2
votes
3answers
365 views

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 ...
2
votes
2answers
462 views

Seed / reseed DRBG too often?

There are limits to how much you can use a the DRBG before you have to reseed it, but are there any limits to how much you must use it before reseeding? Take the following scenarios as an example… ...
2
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2answers
2k views

How to find generator $g$ in a cyclic group?

As generator $g$ is use in DH how to find combination of prime $p$ and $g$? eg: if we choose $p=23$ its generator is $7$ (given in book) how to find it?
2
votes
3answers
524 views

PRNG taking advantage of very large seed

Can anyone suggest a good (CS)PRNG algorithm that takes advantage of having a very large (ideally arbitrarily large) seed? I'd like to use several kilobytes, perhaps several hundred kilobytes, of ...
2
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2answers
497 views

PRNG determinism (and java.security.SecureRandom)

Looking at getDefaultPRNG() in java.security.SecureRandom makes me very unsure about how to use it. On my desktop, it uses sun.security.provider.NativePRNG, which reads from ...
2
votes
1answer
380 views

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 ...
2
votes
1answer
139 views

Is it possible to get better randomness by using multiple PRNGs?

I don't know if this question even makes sense, but: Is there be any benefit or impact to some sort of hierarchical (e.g. a PRNG drives the decision for which PRN to pull from a set of PRNGs) or ...
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 ...
2
votes
1answer
489 views

LFSR using words

If I've got an LFSR, let's say a 16-bit Fibonacci LFSR as shown in the corresponding wikipedia article, which generates maximum length sequences, could I use it to create word sequences instead of bit ...
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. ...
2
votes
1answer
107 views

Recasting randomly generated numbers to other widths

Suppose I have a list of randomly generated uint_8's, uniform over the whole range of uint_8. I write them into a file as raw ...
2
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2answers
352 views

How do I demonstrate that a PRNG not designed for cryptography is not suitable for generating passwords?

This is a replication of this question on Stack Overflow. There's class Random in .NET runtime which is designed for use as a cheap fast source of pseudo-random ...
2
votes
1answer
250 views

Cryptographically strong pseudo-random seq. generators

If a pseudo-random sequence generator is built so that it uses an n-bit seed and outputs a string that is of length x. Let's say one wants to generate a bit string of length y and uses the previous ...
2
votes
1answer
85 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
1answer
67 views

Is this JS library using openssl genrsa -rand improperly?

pem, a JS wrapper around openssl, has the following code in it: var params = ['genrsa', '-rand', '/var/log/mail:/var/log/messages', keyBitsize ]; Am ...
2
votes
1answer
127 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 ...
2
votes
2answers
168 views

GGM PRG construction: Why do we need to change keys all the time with underlying PRG

When constructing a PRF that has n bit input using the GGM PRG, why do we always have to recursively run the PRG using its previous output as a seed key n times. Instead, why don't we run the PRG n ...
2
votes
3answers
2k views

ANSI X9.31 standards for generating random numbers

The NIST-Recommended Random Number Generator Based on ANSI X9.31 Appendix A.2.4 Using the 3-Key Triple DES and AES Algorithms has 3DES being used three times for each 64-bit block of random data ...
2
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2answers
690 views

Avalanche noise RNG for one-time pad use

I came across this little HRNG widget and was really intrigued as I have been looking for a decent but afordable source for truly random bits to use in a one-time pad. The question is, would a HRNG ...
2
votes
1answer
336 views

Proving correctness of pseudorandom generator construction given existing pseudorandom generator

Say if I have a given pseudorandom generator G which takes a k-bit input and outputs a 3k-bit number. How should I show that a specific construction using this pseudorandom generator is valid? For ...
2
votes
1answer
414 views

Generating a cryptographically secure, many-time use, symmetric encryption key

I need to generate a 256 bit encryption key described by the adjectives in the title. Currently I intend to create the key using this RNG. Is this a secure manner of creating the key, given that it ...
2
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1answer
287 views

Conforming Randomness To An Alphabet

Imagine that we're trying to create a function to generate a random string conforming to a user-supplied alphabet. That way, users can generate random strings with given characters. Something like: ...