my $ssh2 = Net::SSH2->new() ;
$ssh2->connect(HOST) or $ssh2->die_with_error ;
$ssh2->check_hostkey(tofu => HOSTKEY) 
    or $ssh2->die_with_error ;
$ssh2->auth_publickey(USER, PUBLICKEY, PRIVATEKEY)
    or $ssh2->die_with_error ;
$ssh2->auth_ok() ;

##</code><code>##

Username/PublicKey combination invalid (-18 LIBSSH2_ERROR_PUBLICKEY_UNRECOGNIZED
) at D:\Perl\ondreamhost.pl line 28.