Using block tea (XXTEA), how can I convert encrypted text into human readable form?
string encryptedText = "ASDFSDAFSADFSDFSDFSDAF"; (assume it is in correct format)
I have the key/pwd also.
There is a Visual Basic implementation of the block tea algorithm here:
http://www.blog-dotnet.com/post/Tiny-Encryption-Algorithm-(TEA)-in-Visual-BasicNET.aspx
Block tea is meant to be easily implementable, so you shouldn't have a hard time converting that to C# (or compiling it into a .NET assembly with VB and then referencing it from .NET).
You should use the above as a base and then modify it as per the XXTEA algorithm, found here:
http://en.wikipedia.org/wiki/XXTEA
Again, it's meant as being easy to implement, so you shouldn't be too hard. If there are specific parts you are having issues with, please make sure to follow up.
Edit1: Core XTEA algorithm in C# with other parts in VB.NET at CodeProject
Tiny Encryption Algorithm and XTEA for the Compact Framework at CodeProject
Here is a JavaScript Implementation of the XXTEA algorithm and here.
Here is a Pascal implementation of all of them.
With all the other answers you should be able to put an implementation together. Once you do it, make a blog or report back here so it is recorded for the next guy!
I found this https://github.com/WooCode/xxTea which is a C# implementation, with unit tests provided. I haven't verified it's accuracy.
Related
I am working on a larger C# project in visual studio handling finance math, so naturally the code implements many special math formulas and they need to be properly documented. I am looking for a good way to produce a documentation from the code. Many objects already have some xml-doc comments with description setup and i am looking for ways to include math formulas written in latex into that.
What options are there and how easy are they to set up?
Or maybe more generally, are there better ways to produce such code documentation?
For me a few things are important:
documenation must have a way to include math formulas.
latex is our preferred syntax to write formulas
ability to use cref-like links in documentation
refactoring (like renaming a class) shouldn't break the links between documentation and object.
it should work with vs-intellisense tooltips and at least show the summary documentation of methods and classes
I tried using Doxygen 1.9.6 (we have also one C++ project) and I manged to make it partially work. it does render latex formulas from the summary tag, but it seems to have issues with certain C# things, for example i cannot make it to generate any documentation for (public) implementations of methods from generic interfaces regardless how i set up the configuration (need to do more research to what exactly is the problem).
I add this as a separate answer because it is completely different approach.
I have found another existing answer which may be helpful.
There are two extensions to VS which support LaTeX formula in comments.
https://marketplace.visualstudio.com/items?itemName=vs-publisher-1305558.VsTeXCommentsExtension (for VS 2017, 2019)
https://marketplace.visualstudio.com/items?itemName=pierreMertz.TeXcomments (works with VS 2010)
For VS 2022 there is new version of the first extension:
https://marketplace.visualstudio.com/items?itemName=vs-publisher-1305558.VsTeXCommentsExtension2022
Maybe Literate Programming is this what are you looking for. Literate programming is a programming paradigm where the documentation and the source code are written in a natural language, making the code easier to read, understand, and maintain. The source code is interspersed with explanations and descriptions that provide context and clarify the purpose and function of the code. This approach aims to make the code more accessible to a wider audience and to improve the overall quality of the code.
The general idea was introduced by Donald E. Knuth and implemented for C. (see http://www.literateprogramming.com)
Tommi Johtela proposed LiterateCS to implement it for C#. It assumes using markdown with LaTeX syntax for math formulas.
General introduction: https://johtela.github.io/LiterateCS/Introduction.html
Example of math formula in the generated documentation: https://johtela.github.io/LiterateCS/TipsAndTricks.html
Need Current SHA-3 C# code?
Greetings,
Does anybody know of good SHA-3 C# code? I'm trying to create my own little dll file in C#. So I'm not really looking for libraries like Bouncy Castle.
I've been running into numerous code examples that say they are SHA-3, but in fact are actually SHA-3 (Keccak) using old code. It's my understanding that although Keccak was the winner, there his been a slight padding change of one bit and the name officially became SHA-3. see FIPS 202.
So I'm looking for SHA3–256 coding that produces an empty string hash of "a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a". The older version (Keccak-256) produces "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470" from an empty string.
Another option would be adding the padding change to the current implementation. However, that's something I don't know how to do.
Thank you in advance.
My original SHA3 port is available:
https://www.nuget.org/packages/SHA3/1.0.0-rc
https://github.com/jdluzen/sha3/tree/netstandard
Use the property UseKeccakPadding to control which padding you need.
This is a self contained port on top of System.Security.Cryptography.HashAlgorithm. It's very small, and can be used directly as is.
I'm looking for some sample projects to read CAPTCHA images. Is there any in C# or VB ?
pseudo code:
String captchaText = CaptchaDecoder(Image captchaImage);
Take a look to:
Text-based CAPTCHA Strengths and Weaknesses. ACM Computer and Communication security 2011 (CSS’2011). link
The authors present a CAPTCHA breaker and explain a generic algorithm to crack standard CAPTCHAs
In this section we present our captcha breaker, Decaptcha, which is
able to break many popular captchas including eBay, Wikipedia and Digg
[...] Decaptcha implements a refined version of the three stage
approach in 15,000 lines of code in C# [...]
This is easier said than done.
This involves either brute-forcing the captcha or running OCR algorithms on it to try and detect what is written in the captcha.
You might want to check this related question: Has reCaptcha been cracked / hacked / OCR'd / defeated / broken?
It also depends on what techniques were used to produce the CAPTCHA. Some distort the text and some squeeze the text.
Your question is a little vague.
Additional reading here: http://en.wikipedia.org/wiki/CAPTCHA
Christian
There are so many types of Captchas out there that you won't find a single library to read them all. If you are only interested in one type though, you might have more luck. Even then, there are lots of variations on Captchas, and the engines frequently produce (whether on purpose or incidentally) tricky ones which even humans can't figure out. Humans can click the little icon to get a new one; your program might not be able to.
This question already has answers here:
How to detect the language of a string?
(9 answers)
Closed 8 years ago.
Is there any C# library which can detect the language of a particular piece of text? i.e. for an input text "This is a sentence", it should detect the language as "English". Or for "Esto es una sentencia" it should detect the language as "Spanish".
I understand that language detection from text is not a deterministic problem. But both Google Translate and Bing Translator have an "Auto detect" option, which best-guesses the input language. Is there something similar available publicly, preferably in C#?
Yes indeed, TextCat is very good for language identification. And it has a lot of implementations in different languages.
There were no ports in .Net. So I have written one: NTextCat (NuGet, Online Demo).
It is pure .NET Standard 2.0 DLL + command line interface to it. By default, it uses a profile of 14 languages.
Any feedback is very appreciated! New ideas and feature requests are welcomed too :)
Language detection is a pretty hard thing to do.
Some languages are much easier to detect than others simply due to the diacritics and digraphs/trigraphs used. For example, double-acute accents are used almost exclusively in Hungarian. The dotless i ‘ı’, is used exclusively [I think] in Turkish, t-comma (not t-cedilla) is used only in Romanian, and the eszett ‘ß’ occurs only in German.
Some digraphs, trigraphs and tetragraphs are also a good give-away. For example, you'll most likely find ‘eeuw’ and ‘ieuw’ primarily in Dutch, and ‘tsch’ and ‘dsch’ primarily in German etc.
More giveaways would include common words or common prefixes/suffixes used in a particular language. Sometimes even the punctuation that is used can help determine a language (quote-style and use, etc).
If such a library exists I would like to know about it, since I'm working on one myself.
Please find a C# implementation based on of 3grams analysis here:
http://idsyst.hu/development/language_detector.html
Here you have a simple detector based on bigram statistics (basically means learning from a big set which bigrams occur more frequently on each language and then count those in a piece of text, comparing to your previously detected values):
http://allantech.blogspot.com/2007/07/automatic-language-detection.html
This is probably good enough for many (most?) applications and doesn't require Internet access.
Of course it will perform worse than Google's or Bing's algorithm (which themselves aren't great). If you need excellent detection performance you would have to do both a lot of hard work and over huge amounts of data.
The other option would be to leverage Google's or Bing APIs if your app has Internet access.
You'll want a machine learning algorithm based on hidden markov chains, process a bunch of texts in different languages.
Then when it gets to the unidentified text, the language that has the closer 'score' is the winner.
There is a simple tool to identify text language:
http://www.detectlanguage.com/
I've found that "textcat" is very useful for this. I've used a PHP implementation, PHP Text Cat, based on this this original implementation, and found it reliable. If you have a look at the sources, you'll find it's not a terrifyingly difficult thing to implement in the language of your choice. The hard work -- the letter combinations that are relevant to a particular language -- is all in there as data.
Has C#/the .NET library builtin routines or constants for converting e. g. millimetres to inches? If so, where can I find them? (I just do not want to produce duplicate code again and again.)
No, there are no such build in routines or constants in the framework.
Totally gratuiitous off topic reply
F# has built in support for units. This is a random blog I just Binged Units Of Measure In F#
Here's a CodeProject sample that does unit conversion:
http://www.codeproject.com/KB/cs/Thunder.aspx
It's not built-in to .Net, but it will save you from having to write all this stuff yourself.
Update: it makes a bit of sense that this would not be part of .Net, because there are issues regarding the degree of precision to use in the conversions and the constants which are probably best left to the developer.
just roll your own set of assemblies which contain the functions so that you don't have to duplicate the code. a simple google search will yield the common conversion formulas. here's a good page.
edited to add the second link...