Encryption compatible between Android and C#

Question

I\'ve found plenty of examples how to do encryption in C#, and a couple for Android, but I\'m particularly looking for a way to handle encrypting (using something like AES,

Answer 1

If you correctly implement the same cipher (like AES) and mode (like CTR, CFB, CCM, etc) on both ends, the ciphertext from one end can be decrypted by the other end regardless of platform.

The Android example you linked to appears to use the ECB mode, and thus is not secure for your purposes. It's critically important that you understand the implications of the block mode you select. It's very easy to get crypto wrong at this level, resulting in a system that's not as secure as you think it is.

EDIT: I take that back, it's not using ECB, but the way it generates the IV is not practical. In any case, my point about understanding the implications of the block modes stands.

You can start with this wikipedia article. Bruce Schneier's book 'Practical Cryptography' is also hugely valuable to anyone implementing cryptographic security.

As to encoding the string, if you must convert the string into ASCII text Base64 is as good a way as any, but I would suggest you investigate use of HTTP PUT or POST to spare you this additional step.