Consider supporting the optional Curve25519 cipher

[SEJeff]

From the FIDO 2 specification ed25519 is Recommended:

Name: Ed25519
Value: 6
Description: Edwards-curve Digital Signature Algorithm on curve 25519
Reference: [RFC8032]
Status: Recommended

It isn't in the supports ciphers in the README or anywhere in the source. Just thought I'd add this here as a "nice to have". Thanks!

[x448]

Do you have a FIDO2 key that supports ed25519? If so, can you provide test data with embedded certs using ed25519? Thanks in advance!

[mitar]

So Yubikeys now use Ed25519 with -8 code. I tried to register:

const COSEAlgEdDSA = -8
webauthn.RegisterSignatureAlgorithm(COSEAlgEdDSA, x509.PureEd25519, x509.Ed25519, 0)

but it does not work. It seems the rest of the code does not support it (for example, assumes there is always a hash involved).