# Tagged Questions

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

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### How does Hash with random cryptography work?

I am new in this world of cryptography and while reading some articles I got stuck into something that I did not understand correctly: the use of hash based on random cryptography. On my knowledge, ...
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### Is pseudo-random letter insertion secure?

Is pseudo-random letter insertion a secure mechanism? I mean by expanding the key or taking two parameters in the encryption function, you select positions in the text at which to insert random ...
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### use the same pad reversed

Suppose I have a random number (eg 625 467 921). I use it once to encrypt a message OTP style, and when I want to use them again, I reverse them (eg to ...
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### data structure of random / compressed data

can anybody explain to me what data structure results after data is compressed? I just try to find out the difference between random data and compressed data, the entropy of both is very high while ...
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### Can we use merely permutation to hide a message?

This question is related to this: When all shares of a secret are given to adversary as a permuted matrix I think the below question is a simplified version of that. Assume we have a 40-bit ...
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### Issue about randomness : what if random looks “human” ? [closed]

I read a lot of stuffs about entropy/randomness. But what if a random generator (either digits or strings) once output a "human" patern ? I know it is very unlikely to happen, but if a random code ...
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### Can shuffling plaintext produce a useable key?

If I 'shuffle' the characters in a long text, is there some number of shuffles that will produce apparent randomness approaching a cryptographically secure random number generator? A chapter in a ...
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### Existence of a random function under constraints

Let $F_1$ and $F_2$ be two random functions taking as input $N$ bits and returning $N$ bits. Let $C_1$ and $C_2$ two constants of $N$ bits. Is there a random function $P$ taking as input $2N$ bits ...
The keys used in an One Time Pad are required to be randomly generated from a keyspace $\mathcal{K}$, we require 256 bit random keys, i.e. $\mathcal{K}=\{0,1\}^{256}.$ Suppose we randomly select an ...
Given two arbitrary/random $n$-bit words, how could one best mix them to get one $n$-bit word for general crypto usages? I suppose that one should have an adequate measure of goodness of the mix ...