hash_init

(PHP 5 >= 5.1.2, PECL hash >= 1.1)

hash_init — Initialize an incremental hashing context

Description

resource hash_init ( string $algo [, int $options = 0 [, string $key = NULL ]] )

Parameters

algo

Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..)

options

Optional settings for hash generation, currently supports only one option: HASH_HMAC. When specified, the key must be specified.

key

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.

Return Values

Returns a Hashing Context resource for use with hash_update(), hash_update_stream(), hash_update_file(), and hash_final().

Examples

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);
?>

The above example will output:

5c6ffbdd40d9556b73a21e63c3e0e904

See Also

• hash() - Generate a hash value (message digest)
• hash_file() - Generate a hash value using the contents of a given file
• hash_hmac() - Generate a keyed hash value using the HMAC method
• hash_hmac_file() - Generate a keyed hash value using the HMAC method and the contents of a given file