These commands generate and use private keys in unencrypted binary (not Base64 “PEM”) PKCS#8 format. The PKCS#8 format is used here because it is the most interoperable format when dealing with software that isn't based on OpenSSL.
OpenSSL has a variety of commands that can be used to operate on private
key files, some of which are specific to RSA (e.g. openssl rsa
and
openssl genrsa
) or which have other limitations. Here we always use