hash_init

(PHP 5 >= 5.1.2, PHP 7, PHP 8, PECL hash >= 1.1)

hash_initInitialize an incremental hashing context

Description

hash_init(
    string $algo,
    int $flags = 0,
    string $key = "",
    array $options = []
): HashContext

Parameters

algo

Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..). For a list of supported algorithms see hash_algos().

flags

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 flags, a shared secret key to be used with the HMAC hashing method must be supplied in this parameter.

options

An array of options for the various hashing algorithms. Currently, only the "seed" parameter is supported by the MurmurHash variants.

Return Values

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

Changelog

Version Description
8.1.0 The options parameter has been added.
7.2.0 Usage of non-cryptographic hash functions (adler32, crc32, crc32b, fnv132, fnv1a32, fnv164, fnv1a64, joaat) with HASH_HMAC was disabled.
7.2.0 Return HashContext instead of resource.

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_algos() - Return a list of registered hashing algorithms
  • 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

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