"4012",
        "VK_VERSION"     => "008",
        "VK_SND_ID"      => "uid100036",
        "VK_REC_ID"      => "EYP",
        "VK_NONCE"       => "2",
        "VK_RETURN"      => "http://127.0.0.1:34211/auth/complete/",
        "VK_DATETIME"    => "2021-02-18T08:48:54+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! SEB 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) . $fields["VK_SND_ID"] .     /* uid100036 */
        str_pad (mb_strlen($fields["VK_REC_ID"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_REC_ID"] .     /* EYP */
        str_pad (mb_strlen($fields["VK_NONCE"], "UTF-8"),   3, "0", STR_PAD_LEFT) . $fields["VK_NONCE"] .      /* 2 */
        str_pad (mb_strlen($fields["VK_RETURN"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_RETURN"] .     /* http://127.0.0.1:34211/auth/complete/ */
        str_pad (mb_strlen($fields["VK_DATETIME"], "UTF-8"), 3, "0", STR_PAD_LEFT) . $fields["VK_DATETIME"] .   /* 2021-02-18T08:48:54+0000 */
        str_pad (mb_strlen($fields["VK_RID"], "UTF-8"),     3, "0", STR_PAD_LEFT) . $fields["VK_RID"];         /*  */
/* $data = "0044012003008009uid100036003EYP0012037http://127.0.0.1:34211/auth/complete/0242021-02-18T08:48:54+0000000"; */
// STEP 4. Sign the data with RSA-SHA1 to generate MAC code
// ========================================================
openssl_sign ($data, $signature, $private_key, OPENSSL_ALGO_SHA1);
/* ja4RGllJrAv0aSJAt5jrb4O956eUC1I7bqdO3x13QpicMwQ1K/wXZFoozSdYHAYLS4ggxSxVnPWse6HjJSikkOIpCnIrYm/OFrXJU4cKM3tqCGNGKzO7jkdfoipx6s9c9DXZimMt8eE8lim6SwlXVWGWlkdOPKm8LHxXrK1Hm0Ipi0aH7BQqGgJMdFek79JVi9lZU6sPwP1frENs+Rh9JQ7gkbNOuurpZhF7Qb4czc1GM6aaS1jDU0jpy6e8ANk6fRxNM92lFEj6nZog9Y9zYAkaFglAO1RbAYXMQGbUw1GCMKKIz0YQ4whPDMvWzk5IPGN7NYRboc8ZkSH0Y6QWFA== */
$fields["VK_MAC"] = base64_encode($signature);
// STEP 5. Generate POST form with payment data that will be sent to the bank
// ==========================================================================
?>
        
        Autentimise näidisrakendus "SEB"