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.
This extension defines a Hashing Context resource returned by hash_init().
以下的常數由此延伸定義,只在這個延伸被編譯成PHP或實行時期被動態載入時有效。