Are there any built-in PHP functions that can help with encrypting letters for display?

One way to encrypt letters for display in PHP is to use the `str_rot13()` function, which performs a simple rotation of the letters in a string by 13 positions. This can be a quick and easy way to obfuscate text for display while still keeping it readable.

$text = "Hello, World!";
$encrypted_text = str_rot13($text);

echo $encrypted_text;