mhash and MD5

[kpWEB]

Below is a portion of code required by authorize.net (an online ecommerce processing center)...

// compute HMAC-MD5
// Uses PHP mhash extension. Pl sure to enable the extension
function hmac ($key, $data)
{
return (bin2hex (mhash(MHASH_MD5, $data, $key)));
}

// Calculate and return fingerprint
// Use when you need control on the HTML output
function CalculateFP ($loginid, $txnkey, $amount, $sequence, $tstamp, $currency = "")
{
return (hmac ($txnkey, $loginid . "^" . $sequence . "^" . $tstamp . "^" . $amount . "^" . $currency));
}

// Inserts the hidden variables in the HTML FORM required for SIM
// Invokes hmac function to calculate fingerprint.

function InsertFP ($loginid, $txnkey, $amount, $sequence, $currency = "")
{

$tstamp = time ();

$fingerprint = hmac ($txnkey, $loginid . "^" . $sequence . "^" . $tstamp . "^" . $amount . "^" . $currency);

As "mhash" is not installed by the server providor, can I just use the internal Md5 functionality with PHP4 instead, or will this yield a different alogoryth entirely?

And on that note, I have a dumb question...what are the "." for in the various strings above, is that basically a concatonation operator?

Thanks kindly, espeically in regards to the newbie "." question

[Mordecai]

I believe MHASH_MD5 yields the same results as md5(). If you want to make sure, just try both with a common string and match the results.

As for the question about periods, yes, they are used to concatenate the string.
"hello".", Clarice" results in "hello, Clarice"
$string."hi" results in the same thing as "$stringhi", but won't screw up if there is a $stringhi as well (nor will it insert spaces).
This is useful if you are using single quotes (') to print strings, so they are not parsed.

[kpWEB]

Unfortunately, I cannot compare mhash (from the above example) against MD5 as I dont not have mhash capability. If anyone does, and can compare, I would be grateful.

[toshog]

so --- is it the same output or not?