Authenticate a session with a public key, read from a file
#include <libssh2.h>
int libssh2_userauth_publickey_fromfile_ex(LIBSSH2_SESSION *session,
const char *username,
const char *publickey,
const char *privatekey,
const char *passphrase);
session - Session instance as returned by libssh2_session_init_ex(3)
username - Pointer to user name to authenticate as.
username_len - Length of username.
publickey - Path name of the public key file. (e.g. /etc/ssh/hostkey.pub). If libssh2 is built against OpenSSL, this option can be set to NULL.
privatekey - Path name of the private key file. (e.g. /etc/ssh/hostkey)
passphrase - Passphrase to use when decoding privatekey.
Attempt public key authentication using a PEM encoded private key file stored on disk
Return 0 on success or negative on failure. It returns LIBSSH2_ERROR_EAGAIN when it would otherwise block. While LIBSSH2_ERROR_EAGAIN is a negative number, it isn't really a failure per se.
LIBSSH2_ERROR_ALLOC - An internal memory allocation call failed.
LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.
LIBSSH2_ERROR_SOCKET_TIMEOUT -
LIBSSH2_ERROR_PUBLICKEY_UNVERIFIED - The username/public key combination was invalid.
LIBSSH2_ERROR_AUTHENTICATION_FAILED - Authentication using the supplied public key was not accepted.