[delta-chat] new android releases / switch to RSA2048 keys

Hi all, there is a new android release out on gplay and f-droid: https://delta.chat/en/2019-03-14-oauth2release one thing that we missed to announce is the default for encryption keys has changed and is now RSA2048 instead of the previous RSA3072. This improves the setup time (often taking 60 seconds, now 10) and also reduces message size. We are aiming to support ECC/ED25519 keys which will much reduce key sizes. If you are wondering if RSA2048 i safe enough you may consider: - gpg (the command line tool) defaults to RSA2048 - Autocrypt setup messages (transfering your secret key) are not safer than RSA2048 encryption keys. - general advise still is that RSA2048 is enough https://paragonie.com/blog/2019/03/definitive-2019-guide-cryptographic-key-… cheers, holger