"1111",
        "VK_VERSION"     => "008",
        "VK_SND_ID"      => "EYP",
        "VK_REC_ID"      => "uid100036",
        "VK_STAMP"       => "2",
        "VK_T_NO"        => "15799",
        "VK_AMOUNT"      => "2825.09",
        "VK_CURR"        => "EUR",
        "VK_REC_ACC"     => "",
        "VK_REC_NAME"    => "",
        "VK_SND_ACC"     => "EE171010123456789017",
        "VK_SND_NAME"    => "Tõõgera Leõpäöldi",
        "VK_REF"         => "26",
        "VK_MSG"         => "My cool payment",
        "VK_T_DATETIME"  => "2021-02-18T18:52:59+0000",
        "VK_ENCODING"    => "UTF-8",
        "VK_LANG"        => "EST",
        "VK_MAC"         => "JQpmGhbrPxVlTRt08tI5zc2rc5KuvLesKWPBrJvl8qJYVudkBBFYOcbtIt8VpGVbjIoXDoi2+h/lcuMK4+kdupR9prQEBNKuO5zFzXr2O2EHYCeInbrhO7HRciFJ1P+dKC6lRoFTkVrLHES9PzB3EGJOJi+ljswmNe+767cnwtjIfp2kNDFNS1V6C9gBwP137FIbUrT+Vx5HoQWsHSDrXRHZwfR/PaQr85iocVMbII+nEeUVdZPrPuwg2lyKp71myY55D82F1KNmMILDxSLZFmsx4jJ44aaNQGYBmiCVE/+IGMxFoSRu/IiMrXLRX8CbbhFrVxoAG/hH/95QsCRP2g==",
        "VK_AUTO"        => "N"
);
// STEP 3. Generate data to be verified
// ====================================
// Data to be verified 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) . $fields["VK_SERVICE"] .    /* 1111 */
        str_pad (mb_strlen($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) . $fields["VK_SND_ID"] .     /* EYP */
        str_pad (mb_strlen($fields["VK_REC_ID"], "UTF-8"),    3, "0", STR_PAD_LEFT) . $fields["VK_REC_ID"] .     /* uid100036 */
        str_pad (mb_strlen($fields["VK_STAMP"], "UTF-8"),     3, "0", STR_PAD_LEFT) . $fields["VK_STAMP"] .      /* 2 */
        str_pad (mb_strlen($fields["VK_T_NO"], "UTF-8"),      3, "0", STR_PAD_LEFT) . $fields["VK_T_NO"] .       /* 15799 */
        str_pad (mb_strlen($fields["VK_AMOUNT"], "UTF-8"),    3, "0", STR_PAD_LEFT) . $fields["VK_AMOUNT"] .     /* 2825.09 */
        str_pad (mb_strlen($fields["VK_CURR"], "UTF-8"),      3, "0", STR_PAD_LEFT) . $fields["VK_CURR"] .       /* EUR */
        str_pad (mb_strlen($fields["VK_REC_ACC"], "UTF-8"),   3, "0", STR_PAD_LEFT) . $fields["VK_REC_ACC"] .    /*  */
        str_pad (mb_strlen($fields["VK_REC_NAME"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_REC_NAME"] .   /*  */
        str_pad (mb_strlen($fields["VK_SND_ACC"], "UTF-8"),   3, "0", STR_PAD_LEFT) . $fields["VK_SND_ACC"] .    /* EE171010123456789017 */
        str_pad (mb_strlen($fields["VK_SND_NAME"], "UTF-8"),  3, "0", STR_PAD_LEFT) . $fields["VK_SND_NAME"] .   /* Tõõgera Leõpäöldi */
        str_pad (mb_strlen($fields["VK_REF"], "UTF-8"),       3, "0", STR_PAD_LEFT) . $fields["VK_REF"] .        /* 26 */
        str_pad (mb_strlen($fields["VK_MSG"], "UTF-8"),       3, "0", STR_PAD_LEFT) . $fields["VK_MSG"] .        /* My cool payment */
        str_pad (mb_strlen($fields["VK_T_DATETIME"], "UTF-8"), 3, "0", STR_PAD_LEFT) . $fields["VK_T_DATETIME"];  /* 2021-02-18T18:52:59+0000 */
/* $data = "0041111003008003EYP009uid1000360012005157990072825.09003EUR000000020EE171010123456789017017Tõõgera Leõpäöldi00226015My cool payment0242021-02-18T18:52:59+0000"; */
// STEP 4. Verify the data with RSA-SHA1
// =====================================
if (openssl_verify ($data, base64_decode($fields["VK_MAC"]), $public_key) !== 1) {
    $signatureVerified = false;
}else{
    $signatureVerified = true;
}
// STEP 5. Display output of the received payment
// ==============================================
?>
    Payment results
    Payment: 
    Signature: