(PHP 5 >= 5.1.2, PECL hash >= 1.1)
hash_init — Initialize an incremental hashing context
Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..)
Optional settings for hash generation, currently supports only one option: HASH_HMAC. When specified, the key must be specified.
When HASH_HMAC is specified for options , a shared secret key to be used with the HMAC hashing method must be supplied in this parameter.
Returns a Hashing Context resource for use with hash_update(), hash_update_stream(), hash_update_file(), and hash_final().
Example #1 Incremental hashing example
<?php
$ctx = hash_init('md5');
hash_update($ctx, 'The quick brown fox ');
hash_update($ctx, 'jumped over the lazy dog.');
echo hash_final($ctx);
?>
上例将输出：
5c6ffbdd40d9556b73a21e63c3e0e904