I'm looking to convert an ed25519 private key to an rsa private key using ssh-keygen.
I found this helpful guide but I am having trouble figuring out how to specify that the input format is ed25519 and the export format should be rsa.
I've tried a bunch of different ways trying to match the synopsis and the description of flags, but every time I try, I get "Too many arguments" error from ssh-keygen.
I'd also like to find the command to generate a public key from a ed25519 private key to verify that it works.
No, it can't be converted. RSA and EdDSA are not just different types of keys, these are totally different Cryptosystems. Key generation algorithms, private keys are just part of it.
All the conversion options available in ssh-keygen are usually convert one type of RSA key to another type of RSA key. e.g. converting OPENSSH RSA key to PKCS8 RSA key. Basically, that so called conversion is just packaging RSA key in different ways.