PHP mhash_keygen_s2k() Function

The mhash_keygen_s2k() function is an in-built function in PHP which is used to generate a key according to the given hash, using a user-provided password. This is the salted S2K algorithm specified in the OpenPGP document (RFC 2440). This function can be used to compute the checksum, message digests, etc. A Salt is a random piece of data used to generate the key. To check the key, you must also know the salt, so it is a good idea to append the salt too.

Syntax:

 
string mhash_keygen_s2k(int $hash, string $password, 
                string $salt, int $bytes)

• $Hash: This parameter holds the hash ID i.e. one of the mhash_name constants.
• $Password: This parameter holds the user's password.
• $Salt: A salt is random data that is used as an additional input to a one-way function that hashes data, a password or passphrase. Salt has a fixed length of 8 bytes and will be padded with zeros if you supply less bytes.
• $Bytes: This parameter represents the key length, in bytes.

Return Value: This function returns the generated key as a string, or FALSE on error.

<?php

$inputString  = "p4ssw0rd" ;
$salt = "agejkhgeuka";

$bytes = "8";

// bin2hex is used to convert binary
// to hex string

print_r(bin2hex(mhash_keygen_s2k(
      MHASH_MD5, $inputString, $salt, $bytes)));

?>

Output:

e2dfb845290aae21