This version of the client is using manual padding with random bytes. This isn't too bad, considering the SHA1 presence.
(See #4 here: https://core.telegram.org/mtproto/auth_key)
The server now supports OAEP, although this has yet to find its way into the docs and clients. We will update. Thank you!
The server now supports OAEP, although this has yet to find its way into the docs and clients. We will update. Thank you!