Message Digest (hash) engine. Allows direct or incremental processing of arbitrary length messages using a variety of hashing algorithms.
The Hash extension requires no external libraries and is enabled by default as of PHP 5.1.2. It may be explicitly disabled by using the --disable-hash switch to configure. Earlier versions of PHP may incorporate the Hash extension by installing the PECL module.
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.