Also no expert about the math behind it but this is how I learned asymmetric encryption with public and private key on a very high level of abstraction:

To encrypt a message you basically take the unencrypted message to the power of the private key (lets call that d) and divide it by the result of a multiplication of two large prime numbers (lets call that N). Now you take the rest of that division, so basically modulo if you are familiar with that.

To decrypt, you take the encrypted message to the power of the public key (e) and divide it by N. The rest of that operation is again the unencrypted message.

So the private and public key are the pairs (d, N) and (e, N) respectively. The great thing about this is that you can post the public key publicly without care and only you, in possession of the private key, can decrypt messages encrypted with your public key. So its easy to verify if you got the key but hard to brute force due to modulo being a one way function. However, this basic RSA approach as described here is not used on its own anymore but rather in combination with other techniques to prevent guessing on very short messages or keys.

There definitely are bugs. But to be fair, for every phone I ever owned the forum looked the same: so many people complaining about so many different problems/bugs/hardware issues that you question why you even bought the phone in the first place. Most often the average user is perfectly fine but would never open up a forum post to announce this.

Someone decided to develop a fork. Posting from it right now. You can download it here

But it’s 1 GB of backups. There seems to be no limit to how much you store, it’s offline after all and syncs peer to peer it doesnt cost them money if you store more stuff. However, I’d be interested to see how easy it is to store you backups on your own somewhere.