Posts: 2
Registered: ‎08-06-2013

Assistance with SIM (VB.NET) Sample Code for payment form



I am attempting to use sample code for SIM (VB.NET) and am having some difficulty. Here is the code I'm currently using:


HTML (may be slightly altered because of this forms HTML checker):


<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="wellsfargo.aspx.vb" Inherits="TDEA.wellsfargo" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<html xmlns="">
<head runat="server">
<form id="form1" runat="server" method='post' action=''>

login id
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<br />
amount<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<br />
<asp:Button ID="Button1" runat="server" Text="Button" />



<input id="HiddenValue" type="hidden" value="Initial Value" runat="server" />
<input type='hidden' runat="server" name='x_login' id='x_login' />
<input type='hidden' runat="server" name='x_amount' id='x_amount' />
<input type='hidden' runat="server" name='x_description' id='x_description' />
<input type='hidden' runat="server" name='x_invoice_num' id='x_invoice_num' />
<input type='hidden' runat="server" name='x_fp_sequence' id='x_fp_sequence' />
<input type='hidden' runat="server" name='x_fp_timestamp' id='x_fp_timestamp' />
<input type='hidden' runat="server" name='x_fp_hash' id='x_fp_hash' />
<input type='hidden' runat="server" name='x_test_request' id='x_test_request' />
<%--<input id="x_relay_response" type="hidden" runat="server" name="x_relay_response" value='TRUE' />--%>
<%--<input type="hidden" runat="server" name="x_relay_url" id='x_relay_url' />--%>
<input type='hidden' runat="server" name='x_show_form' value='PAYMENT_FORM' />







Imports System.Security.Cryptography
Public Class wellsfargo
Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
' start by setting the static values
Dim transactionKey = "REMOVEDFORSECURITY"
Dim amount = ".99"
Dim description = "TDEA Sample Transaction"
' The is the label on the 'submit' button
Dim label = "Submit Payment"
Dim testMode = "false"

' If an amount or description were posted to this page, the defaults are overidden
If Request.Form("amount") <> "" Then
amount = Request.Form("amount")
End If
If Request.Form("description") <> "" Then
description = Request.Form("description")
End If

' also check to see if the amount or description were sent using the GET method
If Request.QueryString("amount") <> "" Then
amount = Request.QueryString("amount")
End If
If Request.QueryString("description") <> "" Then
description = Request.QueryString("description")
End If

' an invoice is generated using the date and time
Dim invoice = DateTime.Now.ToString("yyyyMMddHHmmss")

' a sequence number is randomly generated
Dim random As New Random
Dim sequence = random.Next(0, 1000)

' a time stamp is generated (using a function from simlib.asp)
Dim timeStamp = CInt((DateTime.UtcNow - New DateTime(1970, 1, 1)).TotalSeconds)

'generate a fingerprint
Dim fingerprint = HMAC_MD5(transactionKey, loginID & "^" & sequence & "^" & timeStamp & "^" & amount & "^")

'Print the Amount and Description to the page by placing them in the Spans
'amountSpan.InnerHtml = amount
'descriptionSpan.InnerHtml = description

'Update the fields in the actual form
x_login.Value = loginID
x_amount.Value = amount
x_description.Value = description
'buttonLabel.Value = label
x_test_request.Value = testMode
x_invoice_num.Value = invoice
x_fp_sequence.Value = sequence
x_fp_timestamp.Value = timeStamp
x_fp_hash.Value = fingerprint
End Sub
Function HMAC_MD5(ByVal Key, ByVal Value)
' The first two lines take the input values and convert them from strings to Byte arrays
Dim HMACkey() As Byte = (New ASCIIEncoding()).GetBytes(Key)
Dim HMACdata() As Byte = (New ASCIIEncoding()).GetBytes(Value)

' create a HMACMD5 object with the key set
Dim myhmacMD5 As New HMACMD5(HMACkey)

' calculate the hash (returns a byte array)
Dim HMAChash() As Byte = myhmacMD5.ComputeHash(HMACdata)

' loop through the byte array and add append each piece to a string to obtain a hash string
Dim fingerprint = ""
For i = 0 To HMAChash.Length - 1
fingerprint &= HMAChash(i).ToString("x").PadLeft(2, "0")

Return fingerprint
End Function

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

End Sub
End Class


Once the page goes to the gateway at, I receive the following:


The following errors have occurred.

(33) Credit card number is required.
(33) Expiration date is required.


Ultimately, what I want to do is just come up with the value for "amount" & another unique value on my website, send the user off to the payment form on then send the aforementioned unique value back to my website along with a confirm/deny that the payment went though. I suppose my post is actually 2 questions...


1. Is SIM what I should be using to accomplish what I want to?

2. What am I doing wrong that I'm getting the error I'm getting/Is it on the code side or within my account settings?


TIA, Mike

Posts: 2
Registered: ‎08-06-2013

Re: Assistance with SIM (VB.NET) Sample Code for payment form

I am now able to get the payment form to pull up. Not sure what was causing the error. I rebuilt the page from scratch and now it is working. I still don't know how to send a custom value and return it to my website after payment though.

Posts: 3,093
Registered: ‎03-08-2010

Re: Assistance with SIM (VB.NET) Sample Code for payment form

Anything that is not field name are consider as merchant defined fields which are return on the relay response.

You can post those just like the x_??? field