symetric encryption with key for javascript and ruby

I want to encode a number which would be maximal 10 di开发者_开发知识库gits long using a key with ASCII chars.

The encoded string should be decodable with the same key , which should return the decoded number.

10 => encoding_with("secret_pass") => hash => decoding_with("secret_pass") => 10

Both operations should work the same way in Javascript and Ruby.

What algorythm should I use for this purpose ?

All data should be in ASCII, no multibyte data for input, hash, and the key.

A simple XOR should be sufficient.

JavaScript

Ruby

Yes, you can go overboard and break out the full crypto suite, but since one part of the algorithm will run in-browser, in JS (completely untrusted environment), any attempt at Serious Cryptography™ will give you a false sense of security (in other words, will actually make your system less secure).

If you're trying to protect the data in transit, use the tool that's made for the job; in this case, HTTPS.

I would look into some for of a Symmetric Key Encryption, and the most prominent one AES. AES is pretty much the standard and is implemented in both languages. Just make sure to use the same key and salt for encryption and decryption.

Javascript AES

Ruby AES

If you want it to be simple, and security isn't a great concern (since the javascript... observation in the comments), the easiest way would be to simple generate any random value, bigger (more digits) than the number, and simple XOR it with the number. This assumes the key (=random number) would be previously shared with the other program.

1. generate random number with 10 hex digits -> KEY
2. take the number then do (number XOR key ) -> result
3. send result
4. get the result and do (result XOR key) -> number

something better (stronger) would be to use any public-private key system. Exchange keys, crypt with public on one side, decrypt with private on the other side.