"1012",
        "VK_VERSION"     => "008",
        "VK_SND_ID"      => "uid100049",
        "VK_STAMP"       => "3",
        "VK_AMOUNT"      => "131.72",
        "VK_CURR"        => "EUR",
        "VK_REF"         => "39",
        "VK_MSG"         => "My cool payment",
        "VK_RETURN"      => "http://127.0.0.1:33801/banks/thorbanks_response/",
        "VK_CANCEL"      => "http://127.0.0.1:33801/banks/thorbanks_response/",
        "VK_DATETIME"    => "2021-02-18T18:53:06+0000",
        "VK_LANG"        => "EST",
        "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! LHV 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) . $fields["VK_SERVICE"] .    /* 1012 */
        str_pad (mb_strlen($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) . $fields["VK_SND_ID"] .     /* uid100049 */
        str_pad (mb_strlen($fields["VK_STAMP"], "UTF-8"),   3, "0", STR_PAD_LEFT) . $fields["VK_STAMP"] .      /* 3 */
        str_pad (mb_strlen($fields["VK_AMOUNT"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_AMOUNT"] .     /* 131.72 */
        str_pad (mb_strlen($fields["VK_CURR"], "UTF-8"),    3, "0", STR_PAD_LEFT) . $fields["VK_CURR"] .       /* EUR */
        str_pad (mb_strlen($fields["VK_REF"], "UTF-8"),     3, "0", STR_PAD_LEFT) . $fields["VK_REF"] .        /* 39 */
        str_pad (mb_strlen($fields["VK_MSG"], "UTF-8"),     3, "0", STR_PAD_LEFT) . $fields["VK_MSG"] .        /* My cool payment */
        str_pad (mb_strlen($fields["VK_RETURN"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_RETURN"] .     /* http://127.0.0.1:33801/banks/thorbanks_response/ */
        str_pad (mb_strlen($fields["VK_CANCEL"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_CANCEL"] .     /* http://127.0.0.1:33801/banks/thorbanks_response/ */
        str_pad (mb_strlen($fields["VK_DATETIME"], "UTF-8"), 3, "0", STR_PAD_LEFT) . $fields["VK_DATETIME"];    /* 2021-02-18T18:53:06+0000 */
/* $data = "0041012003008009uid1000490013006131.72003EUR00239015My cool payment048http://127.0.0.1:33801/banks/thorbanks_response/048http://127.0.0.1:33801/banks/thorbanks_response/0242021-02-18T18:53:06+0000"; */
// STEP 4. Sign the data with RSA-SHA1 to generate MAC code
// ========================================================
openssl_sign ($data, $signature, $private_key, OPENSSL_ALGO_SHA1);
/* Wf/u6t9mcI4Kwr2EedBJh15aN3axh+sdFn6fdYapkHuTi9bzlWY5VtQUg59N5/uN2kkptc8faVyJ27mxD0bWOGZWhLQAEPxQ/Q1/mI1zGspZrhejLywJ7NXierddusiF30oBWnAr91Qq1FNmAITyf3d3jcoa3BqfybWuZ/w+R9Z/zpvU4f+2jDBHVe2Rq1caR/2CoEiSg96iRQi4EMs1DzntIpNCWQcWdyDRQGiVtgzO+yjMBm3s2TDcKDLeT3SOgpvg5bz6koFro8VFKJJ8QKqU81SAPKsAChlq1ypMqI+wHuFXPS1butWuAyZIY5q2P6ygrEpmoGO57DYcWrELlg== */
$fields["VK_MAC"] = base64_encode($signature);
// STEP 5. Generate POST form with payment data that will be sent to the bank
// ==========================================================================
?>
        
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