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Small tags/sites

## How to typeset those symbols using MathJax?

I don't know how to typeset the $\Rightarrow$ with the text under it as shown in this image? I know that \xrightarrow{\text{substitution}} gives rise to $\xrightarrow{\text{substitution}}$ but when …

## Authentication using digital signtures

I know a bit of authentication theory, but would like to know how is it really put in practice. There are these software patches that must be distributed periodically. To ensure that only the genuine …

## counting points not on elliptic curve

Given an curve with equation $y^2=x^3+ax+b$, I want to find the number of pairs $(a,b)\in \mathbb{F}_p \times \mathbb{F_p}$ NOT on the curve. How do I do it? I have an intuition that it is $p$, but …

## Doxygen: How to include source files in LaTeX output

I'm using doxygen for the documentation of my program and I'm trying to get the actual source files to be included into the PDF-Output of the LaTeX generator. I've set the following settings in the …

## Program for creating a Keyboard “CheatSheet”

I'm already searching for a while for a program to create a kind of Keyboard Cheatsheet like this: http://www.digitalcombatsimulator.com/upload/iblock/a6d/dcs_a10c_keyboard.png The Keyboard Designer …

## Does it make sense to stretch non-keys?

I was thinking about stretching salt. Key-stretching is good against brute force guessing and assumes your system isn't compromised. Salting a one-way makes it so you have to compute * n for each …

## If H(m) = 0 for some m, how can a DSA signature be forged?

If we know for some message $m$ that $H(m) = 0$, how can we forge a DSA signature with only the public key? I got that $g^s*r = (g^x)^r$ where $x$ is the private key, but that's one equation with 2 …

I'm trying to convert an ant build file to Gradle and I was wondering if there exists a way to specify which packages should be in the javadoc in the same way 'packagenames' works in ant? Thanks ...

## Wrong decrypt return using Air 3.9 for iOS 7 and as3crypto library (AES)

I'm trying to build a security verification of password that send to server a password encrypted (using as3crypto library for AES encryption) and receiving a xml with the same password encrypted again …

## Where can I find understandable pseudocode for MD5 hash function?

My professor is having us implement our own MD5 hash function by only looking up the psuedocode. He said " I would expect about 30 minutes or so to code it." I highly doubt it's that easy to code up. …

## Is applying AES multiple times safer?

The KeePass security help page talks about preventing dictionary attacks To generate the final 256-bit key that is used for the block cipher, KeePass first hashes the user's password using ...

## Is there no information gain using entropy on 2 classes?

I have a very random population I'm trying to split using binary decision tree. Population probability TRUE 51% FALSE 49% So the entropy is 1 (rounded to 3). So for any feature the entropy will …

## Confused about symmetric 128,256 key and the secret provided

I have searched and searched but cannot locate an answer to my question so I am hoping the experts here can. When I read about symmetric encryption like AES I see mention of the key and key size such …

## NodeJS/Meteor how to download many files from external server through request.get and future?

I'm currently having a problem when trying to download many images through a external request.get, bellow are the code var future = new Future(); var images, nome, blob; .each(imoveis, ...

## Is an elliptic curve over $\mathbb{F}_p$ order preserving for the points $(x,y) \in \mathbb{Z}_p$?

Let $E\colon y^2=x^3+ax+b$ be an elliptic curve, and consider its realisation over the finite field of prime order $p$: $E(\mathbb{F}_{p})$. Then if $0<a,b$ is the following true? \forall ...

## Enhance CSPRNG output

If I XOR the output from 2 CSPRNG will the result be better (more random) than the output from either one? Assume one of the PRNG is biased.

## Text and MathJax above symbol

How can regular text and/or MathJax be positioned directly atop a MathJax symbol? Example: http://tex.stackexchange.com/questions/85113/xrightarrow-text. The code there seems bootless on MSE? ...

## Help me review this PHP cryptography implementation for a web-based file server

I'm not a dedicated cryptographer, so I'm looking for someone to look over these functions I wrote and let me know if there are any implementation errors leading to security vulnerabilities or just …

## counting points on elliptic curve

Given an elliptic curve with equation $y^2=x^3+ax+b$, and i want to find the number of points $(a,b)\in E(\mathbb{F}_p)$ where the polynomial has repeated roots, how do i do it? I have an intuition it …

## Problems with specific unix commands while using Jsch (Exec) on Android

Hello i was doing a couple of days and research and some problem analysis, but i have no clue how to solve my Problem right now. Maybe someone can help.... I am using Jsch for Android devices to ...

## Regex searchable word list for space-less monoalphabetic substitution

I am working on teaching myself basic cryptography, in the process I created a simple substitution cipher based on a single alphabet, and a statically defined offset (no key for now). Now that ...

## How to build a jar for Android using command line

I am building a library for use in Android apps. So far I have been using a library project in Eclipse to make a jar file. That works fine, but I'd like to build the jar from source using a ...

## CTR cipher mode secret counter?

Would it be safe to use a CTR mode this way: exchange the nonce with DH but the counter is send unencrypted together with the encrypted data. haven't seen anything about this. IV's don't need to be …

## 32-bit random mapping function

I'm looking for a function f that maps a 32-bit integer into another. The function should be bijective, and though the mapping should look approximately random, it is not required to be ...

## Can insecure algorithms be combined to form a secure algorithm?

This is hypothetical as I can't think of any reason to do this, but out of curiosity.. Could I, for example, take the MD5 digest of a message and concatenate it with the SHA-1 digest (not quite ...

## Scala: Syntax of passing an execution context to Future's map function

A previous version of this question did not come to the point, so I tried to boil it down: The map function of a Future takes an ExecutionContext, as shown below (taken of API 2.10.3) def map[S](f: …

## How to hash using ripemd128 on iOS / OS X?

I would like to hash a string using ripemd128 on iOS / OS X, but there does not seem to be core support for this, or any simple open source framework implementing it. Anyone has a solution?

## Remove padding from a multidimensional array

My assignment is to code a transposition cipher in VB, and I decided that the Route cipher would be the easiest to implement. I have coded the creation of the matrix and the method in which the cipher …

My understanding is that, simply put, a stream cipher is just a CSPRNG such that $R(i,k)$ will produce a deterministic but statistically random sequence, where $i$ is an IV, and $k$ is the session ...