If NULL (or an empty string) is passed, libcurl will pass no public key to
libssh2, which then tries to compute it from the private key. This is known
to work with libssh2 1.4.0+ linked against OpenSSL.
If NULL (or an empty string) is passed, libcurl will pass no public key to
libssh2, which then tries to compute it from the private key. This is known
to work with libssh2 1.4.0+ linked against OpenSSL.