# Questions tagged [randomness]

Usage of randomness (i.e. non-predictable data, usually in the form of bits or numbers) for cryptographic purposes.

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### 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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### Sequence test for an image cipher

I am reading a paper on security analysis of a cipher image using the paper at the following URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8306512&tag=1 It indicates some ...
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### 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 ...
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### 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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### Expected Linear Complexity of a sequence

Let (s) be a sequence of length n. What are the expected linear complexities of (s) and $(s)^{\infty}$ (meaning that the periodic version of s)? I have no idea of the answer to this question? What ...
719 views

### Dieharder input data format. Do I need new line at the end?

I am testing my sequence for randomness using Dieharder with a command like dieharder -a -g 202 -f in.txt >>result.txt my in.txt looks like ...
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### Are there any key exchange schemes that only require entropy on one side?

Are there any cryptographically secure (in terms of confidentiality) key exchange schemes which are usable if one partner in the connection is entirely deterministic and has absolutely no entropy? I ...
107 views

### Is there an algorithm or protocol that allows to securely generate random shuffles when two parties are not colluding without a sever side seed?

I am building an app that pits one party against another party in a gambling transaction – both parties have competing interests and have an incentive not to cheat the other party. I am looking for a ...
1k views

### Public Randomness-Based Random Number Generator using Mobile Phone?

I have an idea to create a True Random Number Generator that use randomness source from a smartphone sensors. My idea is to collect sensors data from a lot of smartphone using mobile apps and then the ...
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### SRP with random, but constant private-value b

In RFC5054, the SRP6a algorithm states that the client and the server should generate random ephemeral private values $a$ and $b$ respectively which are used for further derivation in the handshake ...
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### Why in one time pad must the key distribution to be truly random

One time pad required a truly random key. Why canwt it be a psudo-random key? For example, if the key distribution is that for each bit the probability to get 1 is 0.6 and the probability to get 0 is ...
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### Pad ciphertext with arbitrary number of bits

I have a symmetric-key encryption scheme. I think the output from this scheme (MAC + IV + CBC ciphertext) should already be practically indistinguishable from random, but I would like to pad the ...
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### Beginners question about revealing randomness in probabilistic asymmetric encryption

I am encrypting "1" with probabilistic encryption with a foreign public key (I don't have the private key for it) which results in an encrypted file e. Can I prove to a third party, that e contains ...
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### How can C rand() be exploited if a secure seed is used?

I've just started doing a research project on CSPRNGs and I would like to know what kind of vulnerabilities a regular PRNG has with a secure seed. For example, if I generate a random number using ...
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### Is it possible to compress a random sequence with high entropy?

I have an algorithm that generates a pseudorandom sequence with a length of 100k and high entropy. I would like to check the quality of its randomness. So, I used a popular software program to ...
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### Entropy after shuffling result of /dev/urandom

first of all: Im pretty paranoid. I am creating a seed on my linux server using the following command: cat /dev/urandom |tr -dc A-Z9|head -c\${1:-81} Since I don´...
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### How to calculate entropy of a random number?

I am having a set of random numbers and I want to calculate entropy of them. I searched many entropy calculation formula, but I didn't get it. Can you elaborate a little bit?
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### Assuming that NP = RP, how would this impact cryptography?

In terms of complexity classes, we assume that NP = RP. In other words, we assume that there is a randomized algorithm that solves a NP complete problem (and through polynomial time reductions, ...