Erlang :cryto.generate_key() trouble

I learned now that X25519 and ED25519 public keys are derived in a different way. So you can’t actually use :crypto.generate_key(:ecdh, :x25519) to generate a ED25519 keypairs. You would need something like :crypto.generate_key(:eddsa, :ed25519), but this is currently not possible with Erlang’s crypto app.

So you can only sign/verify with ED25519, but not actually generate the keys.

Not sure if it’s of any help, but you might be interested in trying out enacl, I had a PR that allowed to get the public key from private+seed, but it never got merged.

Hello. I think the issue is now resolved with the last OTP version. Add ed25519 & ed448 support to crypto:generate_key by bkolobara · Pull Request #2329 · erlang/otp · GitHub

We are now able to generate ed22519 keys from the crypto app.

I contributed that PR .

I don’t think it’s part of an OTP release yet. Not that familiar with the release structure, but I think the master branch is going to be the next major version? So it may take some time.

I just upgraded yesterday my OTP version using asdf to take the master, so you can try out.

Erlang/OTP 23 [DEVELOPMENT] [erts-10.4.4] [source-1f6cb54c0a] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Interactive Elixir (1.9.1) - press Ctrl+C to exit (type h() ENTER for help)
:crypto.generate_key(:eddsa, :ed25519)
{<<214, 155, 88, 240, 57, 148, 244, 72, 176, 240, 144, 109, 221, 221, 231, 136,
   212, 128, 30, 246, 119, 190, 236, 1, 200, 155, 212, 213, 120, 184, 80, 53>>,
 <<20, 54, 157, 183, 196, 222, 44, 40, 247, 28, 65, 191, 0, 199, 239, 114, 80,
   255, 49, 149, 86, 229, 173, 196, 16, 5, 13, 73, 78, 180, 50, 108>>}