Pgp key format, strength

Delta Chat version


This is probably a very general question. I didn’t find any information about pgp-key format and strength limitiations.
Yesterday I tried to change to strengthen the key and tested several private/public-key combinations:

  • ecc/ecc Curve 25519/256
  • rsa/rsa 4096/4096
  • rsa/rsa 4096/3072
  • rsa/rsa 3072/3072

The keys were created on the command line by
gpg --expert --full-generate-key
(no password or username, just an email-address).

Afterwards I export private and pulic key seperately, copyied it to /storage/emulated/0/Download and imported the private key with the


The ecc-format wasn’t excepted at all (no import). I hoped to combine performance and more cipher-strength by switching to ecc.
Edit: Just read (linking is not allowed for new users)

A line of heavy activities in the last weeks happend around RPGP, the world’s first full-Rust implemenation of OpenPGP from Friedel Ziegelmayer. His new Rust library supports Autocrypt 1.1 primitives and will allow us to switch from RSA to the shorter and more modern ED25519 keys for e-mail encryption within the next releases. RPGP is working in development builds already. We are working on getting an independent security code review on RPGP.

Any of the rsa-keys were successfully imported.

I could sent messages to a different mail account and read it with thunderbird/enigmail.
However, with none of the rsa-variations I could successfully read messages in the

With the default generated key-pair (rsa/rsa 2048/2048) it worked.

Are there known limitations?