Regarding my previous comment, if you want to be on the safe side and use only ASCII printable seeds (shouldn't matter for SSHA seeds), something like this could be used:
<?php
$salt = substr(base64_encode(pack("H*", sha1(mt_rand()))), 0, 4);
?>
Regarding my previous comment, if you want to be on the safe side and use only ASCII printable seeds (shouldn't matter for SSHA seeds), something like this could be used:
<?php
$salt = substr(base64_encode(pack("H*", sha1(mt_rand()))), 0, 4);
?>