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# Cryptography : Recent Questions and Answers (Page 4)

## Generate AES key from weak string

I'm trying to generate AES256 key from user input password.The size of the password can be anything from 4 bytes long to 32 bytes long but let's assumeit...

## Are the Serpent Test Vectors incorrect?

I have recently written an implementation of Serpent and was testing it against known vectors to no avail. Using 256-bit key, I compared my encryption to the test vectors...

## What is the best deterministic authenticated encryption algorithm to date?

We have a main database where certain properties are PII and want to setup a read-only replica so other parts of the business can able to access (e.g. analytics) We'd...

## Simple explanation of sliding-window and wNAF methods of elliptic curve point multiplication

I'm trying to understand the implementation of elliptic curve point multiplication. I can easily understand the naive double-and-add algorithm, but I'm struggling to find a good explanation / example...

## Can repeatedly encrypting a message with a secure cipher ever produce the original input like what happens in ROT13?

Lets say we have a message 'm'.We encrypt 'm' using a stream cipher or any other type of cipher with cryptographic security that produces an output equal in length...

## Definition of $x^u bmod k$

In RSA, $C=M^e bmod N$ and $d=e^{-1} bmod φ(N)$ are used for encryption and signatures. What is the exact definition of $x^u bmod k$? Also, what is...

## How to recover RSA messages if they are padded with spaces?

I have a message m="hunter". Let's say we pad it with 2 spaces from the left making the final message as m_dash=" hunter". We are given with c where...

Asked on 10/24/2021 by Aviral Gupta

## How to compute $m$ value from RSA if $phi(n)$ is not relative prime with the $e$?

Here is some information we got : We know the value of $n$, with size $1043$. We know the value of $p$ (size $20$) and ...

## Code used for McEliece cryptosystem

In the McEliece cryptosystem, is choice of the code known to the attacker? And if a structural attack succeeded and the attacker found the generator matrix of...

## Chaining one-time signatures

To introduce the notation for the question, consider a one-time signature algorithm:There are a private signing key $sk$ and a corresponding public key $pk$, generated by $Gen(seed)$.To...