I currently work on a projekt (https://github.com/konsultaner/connectanum-dart), that is related to the WAMP-Protocol (https://wamp-proto.org). The protocol supports an athentication algorithem called wamp-cryptosign that is based on the ed25519 private keys. My project currently supports the import of putty private key files and the openssh format (PKCS #8 is planned). The openssh format defines only bcrypt as kdf algorithm. Since wamp is a WebSocket protocol, we would like to store the password encrypted private key in the localstorage. Bcrypt seems to be a quite unsave solution these days. This is the reason why I am requesting argon2 support for the hashing function if this is wanted at all. There is a reference implemetation in c here: https://github.com/P-H-C/phc-winner-argon2