ASP.NET

Private Sub cmdEncrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click<br />
        ' Encrypt<br />
        MyText = Encrypt(textbox1.text, "aabc123a") ' Here aabc123a is the key and textbox1.text is the text which you want to encrypt<br />
    End Sub<br />
<br />
Private Function Encrypt(ByVal strText As String, ByVal strEncrKey As String) As String<br />
        Dim IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}<br />
        Try<br />
            Dim bykey() As Byte = System.Text.Encoding.UTF8.GetBytes(strEncrKey)<br />
            Dim InputByteArray() As Byte = System.Text.Encoding.UTF8.GetBytes(strText)<br />
            Dim des As New DESCryptoServiceProvider<br />
            Dim ms As New MemoryStream<br />
            Dim cs As New CryptoStream(ms, des.CreateEncryptor(bykey, IV), CryptoStreamMode.Write)<br />
            cs.Write(InputByteArray, 0, InputByteArray.Length)<br />
            cs.FlushFinalBlock()<br />
            Return Convert.ToBase64String(ms.ToArray())<br />
        Catch ex As Exception<br />
            Return ex.Message<br />
        End Try<br />
    End Function<br />
<br />
Private Sub cmdDecrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click<br />
        MyText = Decrypt(TextBox2.Text, "aabc123a")<br />
End Sub<br />
<br />
Private Function Decrypt(ByVal strText As String, ByVal sDecrKey As String) As String<br />
        Dim IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}<br />
        Dim inputByteArray(strText.Length) As Byte<br />
        Try<br />
            Dim byKey() As Byte = System.Text.Encoding.UTF8.GetBytes(sDecrKey)<br />
            Dim des As New DESCryptoServiceProvider<br />
            inputByteArray = Convert.FromBase64String(strText)<br />
            Dim ms As New MemoryStream<br />
            Dim cs As New CryptoStream(ms, des.CreateDecryptor(byKey, IV), CryptoStreamMode.Write)<br />
            cs.Write(inputByteArray, 0, inputByteArray.Length)<br />
            cs.FlushFinalBlock()<br />
            Dim encoding As System.Text.Encoding = System.Text.Encoding.UTF8<br />
            Return encoding.GetString(ms.ToArray())<br />
        Catch ex As Exception<br />
            Return ex.Message<br />
        End Try<br />
    End Function<br />
<br />
Remember to add top of import: Imports System.Security.Cryptography