Do you know a good forum/site to send in your hand cipher

Question

Is there any forum or website on the internet except reddit subs where you can send in your hand cipher to get it analyzed?

Answer 1

You can ask such questions on PuzzleSO. They have a cipher tag which has currently 1186 questions.

The tag has the following definition:

A cipher is a simple method of modifying messages to make them unreadable, but still possible to recover. Common ciphers are Caesar, Vigenere, Atbash, and several types of substitution cipher. Other ciphers include polynomial ciphers such as Playfair, Foursquare, etc

Answer 2

The first solution

I suspect that this is an example of an XY problem.

What you want is analysis of your cipher. The pre-supposed solution is to find someone else to do that analysis.

I propose that you already have someone to do that analysis: You!

Try to find a pre-existing design that is similar to yours that has attacks against it. Or find a course on cryptanalysis of (classical) ciphers. Or just sit down and think about what information you have and how you can use it.

Until you are already familiar with all of the standard and/or generic approaches to attacks, then asking for others to do the analysis is counter-productive towards your own education (which is what I presume designing classical ciphers is for) and will not improve your ability to construct superior designs.

Asking questions on crypto.stackexchange

If you are really stuck, and you can make your question narrow and precise, then asking for help on the main site is fine.

However, it is important to note that posting your design and asking for someone to break it is thoroughly frowned upon, and such questions will be closed. We require that you list what you have tried, and where you are stuck.

You would need to have a concise description of the relevant part of the algorithm that you have a question about. It should not be a code snippet - we are more of a math site than a programming site, so explain the design in mathematical terms as best as you can. Try learning to use TeX, it will help the reception of your question significantly.

If in doubt, look for old questions about algorithm design and classical ciphers that were not closed, that received positive votes, and that received answers. Then use such questions as a template to ask your own.

Ask in chat

Once you have sufficient (20) reputation points on the main site, then you can use The Side Channel, which is the chat room for cryptography.stackexchange. You can ask about anything you want there - however, you are not guaranteed an answer.

The pre-supposed solution

I leave this to others to find recommendations here - I don't know of any.

Until you have a design that is noteworthy in some sense (very fast, provably secure, existing analysis, etc) then few knowledgeable people will be interested/willing to work on it.