ed25519 public keys from secret_key.pem

I was asked how to generate the public_key.pem and public_key_hex from a secret_key.pem file.

This is only for default ed25519 keys.

openssl pkey -in secret_key.pem -pubout -out generated_public_key.pem

{ echo -n 01; openssl pkey -outform DER -pubout -in "secret_key.pem" | tail -c +13 | openssl base64 | openssl base64 -d | hexdump -ve '/1 "%02x" ' | tr -d "/n"; } > generated_public_key_hex