# Questions tagged [probability]

Questions about the branch of mathematics concerned with modeling and analyzing random phenomena.

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### False positive error rate of truncated hash match

I’m having difficulty calculating the false positive error probability of matching a prefix of a hash that was truncated to m bits. Say I have string S1 that produces a SHA256 hash H1. I then save the ...
77 views

### Quantifying the success probability of brute force attack against (search) LPN

I've been trying to learn about attacks on LPN ($n$-bit secret, noise rate $\eta$), and have found several allusions to a brute force algorithm that runs in time exponential in $n$ and requires a ...
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1 vote
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### How are probabilities combined in the game hopping proof technique?

I'm currently studying a paper (Sequences of Games: A Tool for Taming Complexity in Security Proofs) on proving semantic security using the Game Hopping technique by Victor Shoup. On pages 9-11, he is ...
• 661
1 vote
91 views

### One time pad, Proof for a problem

We know 2 plaintexts of length L and 2 ciphertexts of length L(we don't know which one belongs which), assuming each given ciphertext is generated by encrypting one of the given plaintexts by XOR'ing (...
• 11
1 vote
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### What is the success probability of a single exploitation attempt for these scenarios

Consider an architectural security measure intended to prevent stack buffer overflow attacks where, instead of storing the return address on the stack, the CPU stores the difference of the stack ...
1 vote
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### Is it possible that a SHA256 hash has the same hex character over and over again?

In theory, there are infinite inputs, that you can hash with SHA-256. So theoretically it would be possible that one hash string would read 0xaaaaaaaa... But would ...
78 views

### What is the best way to accurately describe this statistical probability? [closed]

I am in the process of writing some information for an App. I need to express the probability of something happening but in a way that is correct but easy to understand. I'm confused on the actual ...
• 129
470 views

### Calculating minimum number of messages hashed a 50% probability of a collision (Birthday Paradox)

I encountered this while solving a crypto puzzle. This is the puzzle. ...
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### Likelihood of signature collision with EdDSA

Taking EdDSA as an example, given the length of a signature is 512-bits for a given data payload, what is the probability of a collision where there is another 512-bit value that is also a valid ...
• 1,264
1 vote
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### Probability that rank of a square matrix, whose each element is uniformly random from a ring of integers modulo prime p, is not full

I am currently reading a paper from CRYPTO, which is a top conference in cryptology. In the paper, the authors use a thereom like the one given below without a rigorous proof: the probability that \$...
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### Is it possible to construct a PRNG where the output numbers have a certain distribution of hamming weights?

I am in need of a non-uniform random number generator where each n-bit output has a hamming weight with a certain binomial distribution. For example, I would like a non-uniform PRNG which generates ...
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167 views

### Random Oracle to prove an Authenticated DH protocol

I am trying to understand how they use the random oracle to solve the CDH. For example, in the security proof on page 7 of the following paper; A Lightweight Message Authentication Scheme for Smart ...
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### How to have a bound (upper or lower) of Gaussion distribution over lattice based crypto>

In lattice-based crypto, we always need to sample 'noise' from Gaussian distribution, but how to measure the bound the noise? For example, if the Gaussian distribution is D_{u,\sigma}, where u is the ...
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1 vote