If one looks at Account Settings > End-to-End-Encryption > Add Key and creates a new key then gets the option EC. But you can't choose the bit length nor does one know which curve is used.
Anyone who knows that? Anyone who knows how secure that is?
I've downloaded the source code from the developer site. All the encrypted related parts under the libgcrypt
Libgcrypt is a cryptography library developed as a separated module of GnuPG. It can also be used independently of GnuPG, but depends on its error-reporting library Libgpg-error.
And those are listed as the supported curve in the library
Which one is used? Search files excluding the libgcrypt directory since it is the exact copy of it.
A grep
grep -r curve tools/ build/ calendar/ chat/ mail mailnews/ python/ suite/ taskcluster/ tools/
in the command line displays only
curve25519
This curve is used for public-key signature system as Ed2559.
Curve25519 is also known as the Bernstein curve. It is one of the most secure curves for the listed criteria as in the safecurves.cr.yp.to/.
If you want to read more about how secure the curve is, see our canonical answer;
And note that if ever Shor's period finding algorithm is built with enough qbits the curve will be no more secure.
Also;