How do I create a new key pair and save them in files?

How do I create a new key pair and save them in files? OpenSSL I guess. I have Windows 7 and Xampp, which has OpenSSL in the APache directory (although I am having some problems with openssl_pkey_new() (see Why does openssl_pkey_new() fail?).

Anyway, once I get OpenSSL configured, what does the c开发者_如何学JAVAode look like to create a new key pair and save them in files?

To generate a key pair:

<?php
/* Create the private and public key */
$res = openssl_pkey_new();

/* Extract the private key from $res to $privKey */
openssl_pkey_export($res, $privKey);

/* Extract the public key from $res to $pubKey */
$pubKey = openssl_pkey_get_details($res);
$pubKey = $pubKey["key"];
?>

To save the key to a target file:

file_put_contents($file, $key);