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Small tags/sites

## Non-repudiation and digital signature of a dishonest third party

Let's assume a dishonest Alice who sends, encrypts & digital signs a message to Bob. Bob stores the decrypted message and the digital signature in a database. However Alice is a bad girl and ...

## Convert a string into a key

Is there a way to convert a string into a key so I can have the same encryption key for encoding/decoding? I do not mean using SecretKey btw. Key symKey = ...

## Given Final Block not properly padded while AES decryption

First, I'll tell what is my primary goal. I'm going to use AES to encrypt some content in the client side, then use RSA public key to encrypt the important AES specs and sending both AES encrypted ...

## Android - RSA algorithm : Decrypts a message with any private key

I am having a serious problem with the RSA asymmetric cryptography algorithm. A message encrypted using User A public key is being decrypted by the User's private key. On the computer it works fine. ...

## sftp fails with 'message too long' error

My java program uses ssh/sftp for transferring files into linux machines (obviously...), and my library for doing so is JSch (though it's not to blame). Now, some of these linux machines, have shell ...

## Existing Java implementation of $2y$?

I'm going to be doing some integration work between Java and an existing PHP app. PHP stores user passwords using the PHP function password_hash(), which implements the $2y$ Blowfish mode ...

## cryptographic issue on Android 4.4.2

I tried to run two examples cryptographic. Doing debugging with emulators via eclipse everything works fine, debugging with the physical device I get an error: pad block corrupted the code is ...

## Futuro or Subjuntivo to talk about a belief in a future event in a negative form

Objective Clarify which one to use 'Futuro' or 'Subjuntivo' (or it does not matter) to say "I do not believe/think it will rain tomorrow". No creo que lloverá mañana. No creo que llueva mañana. ...

## XOR cipher with three different ciphertexts and repeated key, key length known. How do I find the plaintexts?

Let us say we have three different plaintexts (all alphabets, A-Z): $x$, $y$ and $z$, each of length $21$. Let the key, $a$, be also of length $21$. Now, what we have is $x \oplus a$, $y \oplus a$ ...

## How to decrypt the ppp protocol data content?

One of our applications needs to connect to VPN connection and run it. when I captured traffic I see transaction of this program under PPP protocol. but content of transmission are compressed or ...

## Gradually learning the keybindings provided by AUCTeX

If I do M-x forward-char, Emacs gives a very useful message You can run the command "forward-char" with C-f. Considering the fact that Emacs can find all LaTeX keybindings in the file latex.el ...

asked 7 hours ago by Name on emacs.stackexchange.com

## Why is it a quadratic equation?

In Groth-Sahai NIZK proof system, they have defined something called Quadratic Equation in $\mathbb{Z}_n$ as shown below. But, my idea of quadratic equation was a second order polynomial equation in a ...

## Parallel Pollard's Rho: Number of distinguished points

When using the parallel version of Pollard's Rho algorithm for discrete logs, each processor performs its own random walk to find distinguished points, and reports the starting point and the ...

## Regexp not working

I messed up my latex code; I need to replace \cite[42]{source}. with .\cite[42]{source} and \cite{source}. with .\cite{source}. I tried \\cite$$.*$$\}\. -> .\\cite\1\} but I got an error: Invalid ...

## How to save a web page with its certificate?

I've made a payment to an online store and they're claiming there's no order with the number that appeared in my screen, therefore they're refusing to send me the product. I still have the page opened ...

## One-way function definition

I cannot understand why a one-way function $f$ is defined in this way $\text{Pr}(f(A(f(x))) = f(x)) < \frac{1}{p(n)}$ and not $\text{Pr}(A(f(x)) = x) < \frac{1}{p(n)}$ where $A$ is a ...

## Is it possible to encrypt the entirety of a video by encrypting specific frames?

I would have thought that if I encrypted all I-frames, the rest of the video would be encrypted because B- and P-frames are both derived from I-frames. Having done a little bit of testing - ...

## CBC Fiestel network chiper implementation

Ive built a fiestel chiper algorithem and Im using CBC for blocks. Im sitting on this code for over a week now, and I think my implementation of CBC is wrong. This is hoe I implemented CBC: When ...

## Proof that $gcd(e, \lambda(N)) = 1 \hspace{1mm} \Longleftrightarrow \hspace{1mm} gcd(e, \varphi(N)) = 1$

What is the proof for the fact that $gcd(e, \lambda(N)) = 1 \hspace{1mm} \Longleftrightarrow \hspace{1mm} gcd(e, \varphi(N)) = 1$ Where: $N = P * Q$ where $P$ and $Q$ are both primes. $\varphi(N)$ ...

## Using a non-function command in a tkinter button

I am trying to make a popup input window (for context the user is asked for an input and a key, if the key is blank then this window will pop up with an Entry bar asking for a new key, when the user ...

## Do any stream ciphers with aperiodic keystreams exist?

Exactly what it says on the tin. I can imagine constructing such keystreams from: The binary expansions of irrational numbers Chaotic systems like the logistic map or the Lorenz attractor. The ...

## What's a good way in Akka to wait for a group of Actors to respond?

In Akka, I want to send out a "status" message to actors in a cluster for their status. These actors may be various states of health, including dead/unable to respond. I want to wait up to some ...

## $a$ has a square root modulo $p$ if and only if its discrete logarithm log$_{g}(a)$ modulo $p - 1$ is even

Questions: Let $p$ be an odd prime and let $g$ be a primitive root modulo $p$. Prove that $a$ has a square root modulo $p$ if and only if its discrete logarithm log$_{g}(a)$ modulo $p - 1$ is even. ...

## Python RSA Brute Force Check

I have an exercise to brute force a piece of text that has been encrypted with a very small key. The public key I have is (e = 5, n = 203). The text has been converted to ASCII, shifted a fixed number ...

## minimal entropy approximation of a discrete random variable

Let $X$ be a $\mathbb{N}$-valued random variable. Define $$H^\epsilon_n(X) = \inf_f H(f(X))$$ where $f$ runs over all functions $\mathbb{N} \to \mathbb{N}$ such that $\Pr(f(X)\neq X)<\epsilon$ ...

## Is Computer Modern a high-quality font?

Computer Modern, a font created by a computer scientist for use with his own typesetting system TeX, has become one of the most frequently used fonts of all time, precisely because of the popularity ...

## AES javascript encryption and Java decryption

I've already implemented RSA encryption in javascrypt and RSA decryption in java which is just a simple process. But the problem I've to encrypt a large amount of data which is not possible for RSA at ...

## Where to store hashes, salts, keys in Desktop Applications

I am trying to figure out where or how i should store application secrets and keys inside a desktop application. For example a facebook app key or dropbox key and secret. So I've read that i should ...