use Crypt::PK::RSA;
my $pk = Crypt::PK::RSA->new();
$pk->generate_key(256, 65537);
my $private_pem = $pk->export_key_pem('private');
my $public_pem = $pk->export_key_pem('public');

##</code><code>##

-----BEGIN RSA PUBLIC KEY-----
...
-----END RSA PUBLIC KEY-----

##</code><code>##

$ ssh-keygen -y -f privatekey > publickey