"4012",
        "VK_VERSION"     => "008",
        "VK_SND_ID"      => "uid100010",
        "VK_REC_ID"      => "SAMPOPANK",
        "VK_NONCE"       => "4",
        "VK_RETURN"      => "http://127.0.0.1:45887/auth/complete/",
        "VK_DATETIME"    => "2021-02-18T09:22:33+0000",
        "VK_ENCODING"    => "UTF-8",
);
// STEP 3. Generate data to be signed
// ==================================
// Data to be signed is in the form of XXXYYYYY where XXX is 3 char
// zero padded length of the value and YYY the value itself
// NB! Danske expects symbol count, not byte count with UTF-8,
// so use `mb_strlen` instead of `strlen` to detect the length of a string
$data = str_pad (mb_strlen($fields["VK_SERVICE"], "UTF-8"), 3, "0", STR_PAD_LEFT) . $fields["VK_SERVICE"] .    /* 4012 */
        str_pad (mb_strlen($fields["VK_VERSION"], "UTF-8"), 3, "0", STR_PAD_LEFT) . $fields["VK_VERSION"] .    /* 008 */
        str_pad (mb_strlen($fields["VK_SND_ID"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_SND_ID"] .     /* uid100010 */
        str_pad (mb_strlen($fields["VK_REC_ID"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_REC_ID"] .     /* SAMPOPANK */
        str_pad (mb_strlen($fields["VK_NONCE"], "UTF-8"),   3, "0", STR_PAD_LEFT) . $fields["VK_NONCE"] .      /* 4 */
        str_pad (mb_strlen($fields["VK_RETURN"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_RETURN"] .     /* http://127.0.0.1:45887/auth/complete/ */
        str_pad (mb_strlen($fields["VK_DATETIME"], "UTF-8"), 3, "0", STR_PAD_LEFT) . $fields["VK_DATETIME"] .   /* 2021-02-18T09:22:33+0000 */
        str_pad (mb_strlen($fields["VK_RID"], "UTF-8"),     3, "0", STR_PAD_LEFT) . $fields["VK_RID"];         /*  */
/* $data = "0044012003008009uid100010009SAMPOPANK0014037http://127.0.0.1:45887/auth/complete/0242021-02-18T09:22:33+0000000"; */
// STEP 4. Sign the data with RSA-SHA1 to generate MAC code
// ========================================================
openssl_sign ($data, $signature, $private_key, OPENSSL_ALGO_SHA1);
/* cWZx27wnUBCAhaamIYpko4pWQ8kjVjcTBsFhTbRs5DbPeg6yAu5U6Cbls1RDwF2Pr15bs1CYqsUK4ZBK+eatMVMsKkOcIjcD71CHKAFGT3h9AuaGxL/W3QcID5Z2YCukXWKVFeM+/C8EH3/GKEm+VVjsChRpKPvXMPiCF+TNK+3tpPKtLq6PoqLjd0HNqAdfV4FjFgZEW1heWcpQ1CTnFxfwsnGq64NDSf5KWfs6rIlJfuuEZv2mDwv7fcIXneeHBnk0kVLlpgxXmXvb1hVbR8IN+DCosfb3qBiuhB7eWdBfs7h5YNytitIAeBTexfTH6zOX1CoznrpsQCJb4jPIgA== */
$fields["VK_MAC"] = base64_encode($signature);
// STEP 5. Generate POST form with payment data that will be sent to the bank
// ==========================================================================
?>
        
        Autentimise näidisrakendus "Danske"