AES Encryption / Decryption for Beginners

Question

I am trying to encrypt NSString of both NSString and NSData in Objective-C, and so I started searching.

I started from here , but unfortunately it hit my head.

Then I found myself in this post , and it was very easy to follow, so I went and tried to figure out the implementation . Having studied the implementation, I saw the second answer on this post and saw that it had more adaptive implementations that led me to configure it . According to the gist readme, he "took down this Gist due to concerns about the security of the encryption/decryption" . This makes me think that implementation security from above also has security flaws.

From the same principle, he mentioned another alternative that I could use for encryption. After looking at the code, I noticed that it generates NSData using "a header, encryption salt, HMAC salt, IV, ciphertext, and HMAC" . I know how to handle this in order to decode the same library again, but how would I pass this to the server, given that I do not quite understand what I am sending to it?

At the heart of all this, I am above my head. Given what I said above, and knowing that I don’t have time to take on a lot of training for this, if only if it is absolutely necessary, what is the best way to handle this encoding / decoding process, given the private key with the ultimate goal ship it to a server that is not developed by me? (How's it for a run in a sentence!)

Answer 1

Maybe you should ask the server guy? Whenever you ever have encryption between batches too much, you should have some kind of agreement regarding the format of this data, raw primitives can't do it alone, not to mention that it's easy to ruin things that are protected with just primitives and the desire to just send the encrypted text aes will lead to errors.

The RNCryptor you mention is a high-level encryption library that defines a simple format that others should also follow, so it makes it easier to switch to another platform, but it has additional features necessary for AES to work properly. There are other libraries ( NaCL , GPGME and Keyczar ) that are not so simple in format but easy to use, so you will need to use the library at both ends, but I highly recommend that you use something like this if possible, but don't collapse your own.

Keyczar specifically exists for java, python, C ++, C #, and go, so if you can use the C ++ version on iOS (or the Mac that you focus on the client), you can be good on the server, as there are several options.