Usage of randomness (i.e. non-predictable data, usually in the form of bits or numbers) for cryptographic purposes.
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2answers
68 views
random number generator 10-side dice alternative
A lot of sites like this one Here, refer to 10-side dice to generate random number for otp. I was thinking about new ways to generate random numbers,letters and passwords. here what I got.
to ...
4
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1answer
153 views
Quality of randomness on a Linux system with haveged
Has anyone checked if using haveged, a Linux daemon which uses the HAVEGE algorithm, changes the non-deterministic properties of the random data from ...
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2answers
66 views
How secure is passing a MAC to Python's random.seed before using random.choice to generate a MAC?
I'd like to use Python's random.choice seeded with a HMAC-SHA1 tag to generate a MAC encoded in a variable set of chars.
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2
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0answers
113 views
Correct way to truncate data to a range
2 hours ago I thought I had this figured out, but now I am doubting myself and want someone to validate my algorithm.
I want to take a stream of k trusted random ...
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2answers
84 views
How does the rand() function in C work? [closed]
I want to know how rand() works (even when I don't provide any seed how it produces PRNs?) thanks!
2
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2answers
156 views
How to efficiently generate a stream of independent, but biased random bits?
Usually, in cryptography, one is interested in debiasing a stream of independent (true) random bits, and several algorithms exist to do this. What about the converse? Let's assume I have a stream of ...
1
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1answer
96 views
How to generate a random polynomial of degree $m$?
I am trying to do a homework in which implement a variation of this paper and I don't know how to generate a polynomial of degree $m-1$. This polynomial is used to generate the $y_0$ and $y_1$ values.
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2
votes
1answer
97 views
Crypto puzzle as proof of randomness?
I need an untrusted client to generate a random public/private keypair (in particular, an Ed25519 keypair, which can be generated really fast), but I'm only allowed to see the public key. The ...
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1answer
62 views
use the same pad reversed
lets say I have this random numbers ' 625 467 921 ' and use them once to encrypt a message otp style and then I want to use them again so I reverse them to be ' 129 764 526' and use to encrypt the ...
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4answers
287 views
Randomized algorithms and the one time pad
The way I understand it, an algorithm is said to be randomized if it uses randomness as part of its logic (quoting Wikipedia). Now, in the case of encryption algorithms, I assume this means that for ...
1
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1answer
175 views
How to test distribution of a hash function?
From what I've found, it is generally accepted a cryptographic hash function like SHA-2 has an evenly, randomly distributed output. Is there a way to test this without running through the entire ...
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1answer
149 views
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 ...
3
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1answer
168 views
Using chi square for distinguishing between compressed and random data
I am trying to find some measurement for identifying and distinguishing between compressed and random data. I tried this first by computing the entropy of such data, the entropy value is extremely ...
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2answers
187 views
Is just a bit of random, “fully random”?
I understand that hashing a datetime is a pseudo-random number, and not good in a security context.
But what about hashing a datetime plus a truly-random but constant string (just a string that an ...
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2answers
306 views
Are mouse movement coordinates useful as a seed for a RNG?
Is it good to use a mouse movement as a 64-bit random seed for a Pseudorandom Generator like AES in Counter Mode?
Should I only need to get the X and Y coordinates of the mouse movement?
2
votes
1answer
166 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:
...
0
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1answer
89 views
Combatting traffic shape analysis with spurious packets
I was reading a question about combatting traffic analysis, and a thought occured. If I send random junk messages periodically, would that defeat traffic analysis?
The messages would contain some ...
2
votes
2answers
198 views
How to decrypt this RSA-like cipher
Suppose we have a RSA-type Modulus $n = pq$ with $p,q$ prime. We also pick a random public exponent $e$ with $\gcd(e,\varphi(n)) = 1$ and compute the private exponent $d$ with $de \equiv 1 ...
5
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1answer
297 views
Why are MACs in general deterministic, whereas digital signature constructions are randomized?
The fact is I'm not quite sure if my question statement is true, however all the MAC constructions I know of (e.g. CBC-MAC, CMAC, HMAC) are deterministic, whereas many constructions for digital ...
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2answers
183 views
How can encryption involve randomness?
If an encryption algorithm is meant to convert a string to another string which can then be decrypted back to the original, how could this process involve any randomness?
Surely it has to be ...
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1answer
155 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 ...
0
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1answer
114 views
BigInteger in Java and Randomness
I'm looking for some PRNGs and as I have been using Java for a long period of time I thought that the BitInteger class together with the Random class could both generate some large pseudo random ...
3
votes
1answer
162 views
Is a subset of a random set still random?
Suppose you have an infinite list of random bytes, and you select the first N bytes that correspond to printable ASCII characters. Is this list of N bytes still as secure (e.g. for the purpose of a ...
4
votes
3answers
248 views
Is there some way to generate a non-predictable random number in a decentralised network?
Is there a way to generate a random number with given restrictions:
It will be used in a decentralised network with a big number of peers (no central authority to generate it)
Its generation should ...
3
votes
4answers
494 views
Stretching a random seed to maximize entropy
I'm using a random number generator that requires me to pass it a big (several kilobytes) pool of random data for initialization.
I've gathered entropy from various system metrics (free memory, ...
4
votes
1answer
629 views
ElGamal Signature Scheme: Recovering the key when reusing randomness
Show how if Alice uses the same value of $k$ to sign two different messages $m_1$ and $m_2$, using the ElGamal signature scheme, Eve can recover the value of $a$ from the corresponding signatures ...
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3answers
2k views
How to generate a list of unique random strings?
How would you generate a list of distinct random strings, where all strings are alphanumeric and have a fixed length?
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1answer
228 views
How to enhance randomness of AES?
I'm using PHP to encrypt a string and Java to decrypt it on a remote server. To perform the encryption, I'm using the strategy that can be found here.
My problem is that the strings I encrypt are ...
8
votes
3answers
585 views
What is the use of REAL random number generators in cryptography?
I understand the use of pseudo-random number generators. I am not getting mixed up between these and "real" random number generators.
However, I don't understand for what a real random number ...
48
votes
10answers
3k views
Is modern encryption needlessly complicated?
RSA, DES, AES, etc. all use (relatively) complicated mathematics to encrypt some message with some key. For each of these methods, there have been several documented vulnerabilities found over the ...
18
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4answers
431 views
Necessity of Randomness of Salts?
Given the desire to have unique salts for each user of your system, is it actually necessary to create a cryptographically-random salt for each user? If your system already has some other unique user ...
