Using hash_hmac() to Generate HMAC Hashes with a Key in PHP

The hash_hmac() function in PHP generates a keyed hash value using the HMAC method. Its signature is

string hash_hmac(string $algo, string $data, string $key, bool $raw_output = false)

.

Parameters

algo : The name of the hash algorithm to use (e.g., "md5", "sha256", "haval160,4"). Use hash_algos() to retrieve the list of supported algorithms.

data : The message to be hashed.

key : The secret key used for HMAC generation.

raw_output : Set to true to return raw binary data; set to false (default) to return a lowercase hexadecimal string.

Return value

If $raw_output is true, the function returns the raw binary hash; otherwise it returns a lowercase hexadecimal string. If the specified algorithm is not supported, hash_hmac() returns false.

Example

<?php
echo hash_hmac('ripemd160', 'The quick brown fox jumped over the lazy dog.', 'secret');
?>

Output

b8e7ae12510bdfb1812e463a7f086122cf37e4f7