Description:
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The mcrypt_encrypt manual page (http://php.net/manual/en/function.mcrypt-
encrypt.php) says that:

It is recommended to use the mhash functions to create a key from a string.

But the introduction of the mhash manual 
(http://php.net/manual/en/intro.mhash.php) says that:

Note: This extension is obsoleted by Hash.

Here (http://php.net/manual/en/migration53.removed-extensions.php) it also 
stated that:

mhash - Discontinued; use the hash extension instead. hash has full mhash 
compatibility; all existing applications using the old functions will continue 
to work.

-----------------------

The problem is that there's no hash alternative for 
http://www.php.net/manual/en/function.mhash-keygen-s2k.php.

I'm filling this as a documentation bug, but I'm not exactly sure if it should 
be filled in some other category (perhaps feature request?) because at the 
moment we have no other way to do what mhash_keygen_s2k() used to do.