При разработке asp страниц Вам потребуется алгоритмы хэширования данных. Ниже показаны примеры их использования. 

Public Function GetHash(ByVal number As String, ByVal Algoritm As String) As String
GetHash = ""
'Create an encoding object to ensure the encoding standard for the source text
Dim ASCIIenc As New ASCIIEncoding
'Retrieve a byte array based on the source text
Dim ByteSourceText() As Byte = ASCIIenc.GetBytes(number)
'Instantiate an Provider object
Dim ByteHash() As Byte = Nothing
Select Case Algoritm
Case "MD5"
Dim DataHash As New System.Security.Cryptography.MD5CryptoServiceProvider
ByteHash = DataHash.ComputeHash(ByteSourceText)
Case "SHA1"
Dim DataHash As New System.Security.Cryptography.SHA1CryptoServiceProvider
ByteHash = DataHash.ComputeHash(ByteSourceText)
Case "SHA256"
Dim DataHash As New System.Security.Cryptography.SHA256Managed
ByteHash = DataHash.ComputeHash(ByteSourceText)
End Select

'Compute the hash value from the source
'Cycle through the hash and convert to string
If ByteHash IsNot Nothing Then
For Each b As Byte In ByteHash
'Convert byte(s) to string
GetHash &= b.ToString("x2")
Next
End If
End Function