Erlang 24 Support

[mjquinlan2000]

Hi, this PR is not 100% done, but I believe it's a step in the right direction.

I have created a Cloak.Crypto module to intercept the calls to crypto and change based on System.otp_release/0
I have created a Cloak.Crypto.Interface behavior to ensure the functions across erlang versions.

There are a couple of things still broken mainly because I am a little out of my depth in the knowledge of ciphers in general.

First, the only version this seems to partially work on is erlang 24 and up. I don't know why but when I set the erlang version to anything less than 24 (i.e. 22 & 23), it gives me an 'Unknown Cipher' error even though the API should be the same.

Second, I am having trouble getting the AES.GCM functions to encrypt properly on erlang 24. I am missing something with the contract that is causing the decrypt to not work.

@danielberkompas if you could give me a push in the right direction it would be greatly appreciated.

[mjquinlan2000]

I think I just found all the answers in section 6.5 of the crypto User's Guide.

https://erlang.org/doc/apps/crypto/new_api.html#retired-cipher-names

I will push a change shortly

[mjquinlan2000]

I figured everything out. I just messed up some calls to :crypto.crypto_one_time_aead. Passing now

[mjquinlan2000]

Related to #102

[wingyplus]

I see a similar PR (#103) and they look still active on PR.

[mjquinlan2000]

@wingyplus I see that, but I don't agree with the way that they are coupling the cipher modules to the :crypto contract. The calls from Cloak.Cipher.* to the crypto API should be opaque and wrapped in a facade. They are also not dealing with the deprecated modules.

Of course, that's my design opinion and I don't care much either way. I'm just trying to get something out there that works so I can use Cloak with erlang 24

[coladarci]

Just want to thank you all for working on this - this is my only blocker for Elixir 1.12 so I'm so appreciative of you putting time into this!

[wingyplus]

Just want to thank you all for working on this - this is my only blocker for Elixir 1.12 so I'm so appreciative of you putting time into this!

If you want to go elixir 1.12. I recommended to go with otp 23 which is not breaking this libraray.

[danielberkompas]

Looks good! I'll make a few tweaks before releasing it, but nothing that will block this PR.

[kenny-evitt]

Sorry all for 'butting in', but someone pointed me at this PR in response to a question I had about similar changes in my own project; the forum post where I asked the question:

• Help with reading 'typespecs' for Erlang crypto module - Questions / Help - Elixir Programming Language Forum

Basically, I couldn't seem to use the :aes_ctr cipher with the new crypto functions – I had to use one of the explicit-key-length versions. That was and is a little confusing to me as it seems like :aes_ctr should be valid and I didn't change the system OpenSSL library I'm using either.

I also noticed that you seem to have made a similar change, i.e. using the :aes_256_ctr cipher instead of :aes_ctr, for OTP 24+.

Do any of you have any insight as to why that's required? I'm just curious! And feel free to ignore me :)

(This is a nice library BTW!)