Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..)
data
Message to be hashed.
key
Shared secret key used for generating the HMAC variant of the message digest.
raw_output
When set to TRUE, outputs raw binary data.
Default value (FALSE) outputs lowercase hexits.
Return Values
Returns a string containing the calculated message digest as lowercase hexits
unless raw_output is set to true in which case the raw
binary representation of the message digest is returned.
Examples
Example 1. hash_hmac() example
<?php echo hash_hmac('ripemd160', 'The quick brown fox jumped over the lazy dog.', 'secret'); ?>