apache_md5_crypt() provides a function compatible with Apache's .htpasswd files.
This was contributed by Bryan Hart <bryan@eai.com>. This function is exported by
default.

The unix_md5_crypt() provides a crypt()-compatible interface to the rather new
MD5-based crypt() function found in modern operating systems. It's based on the
implementation found on FreeBSD 2.2.[56]-RELEASE. This function is also exported
by default.

For both functions, if a salt value is not supplied, a random salt will be
generated, using the function random_md5_salt(). This function is not exported
by default.