Public Function Base64_HMACSHA1(ByVal sTextToHash As String, ByVal sSharedSecretKey As String)
Dim asc As Object, enc As Object
Dim TextToHash() As Byte
Dim SharedSecretKey() As Byte
Set asc = CreateObject("System.Text.UTF8Encoding")
Set enc = CreateObject("System.Security.Cryptography.HMACSHA1")
TextToHash = asc.Getbytes_4(sTextToHash)
SharedSecretKey = asc.Getbytes_4(sSharedSecretKey)
enc.Key = SharedSecretKey
Dim bytes() As Byte
bytes = enc.ComputeHash_2((TextToHash))
Base64_HMACSHA1 = EncodeBase64(bytes)
Set asc = Nothing
Set enc = Nothing
End Function
Private Function EncodeBase64(ByRef arrData() As Byte) As String
Dim objXML As MSXML2.DOMDocument
Dim objNode As MSXML2.IXMLDOMElement
Set objXML = New MSXML2.DOMDocument
' byte array to base64
Set objNode = objXML.createElement("b64")
objNode.DataType = "bin.base64"
objNode.nodeTypedValue = arrData
EncodeBase64 = objNode.Text
Set objNode = Nothing
Set objXML = Nothing
End Function