PHP: How can I generate a HmacSHA256 signature of a string

Question

Is there any way to create a HmacSHA256 signature of a string in php?

Answer 1

Here is an example of datatrans transaction signing (swiss e-payment solution) before call PSP with HMAC-SHA-256.

Hope it could help some developers.

$hmacKey    = 30911337928580013;

$merchantId = 1100004624;
$amount     = $total * 100;
$currency   = 'EUR';
$refno      = $orderId;

// HMAC Hex to byte
$secret     = hex2bin("$hmacKey");

// Concat infos
$string     = $merchantId . $amount. $currency . $refno;

// generate SIGN
$sign       = bin2hex(hash_hmac('sha256', $string, $secret)); 

Note: the merchant ID and HMAC key are both from Datatrans documentation available here : https://admin.sandbox.datatrans.com/showcase/doc/Technical_Implementation_Guide.pdf