Base64 encoding / decoding functions in VbScript / Classic ASP

base64.inc.asp

<%
Function Base64Encode(sText)
    Dim oXML, oNode
    Set oXML = CreateObject("Msxml2.DOMDocument.3.0")
    Set oNode = oXML.CreateElement("base64")
    oNode.dataType = "bin.base64"
    oNode.nodeTypedValue = Stream_StringToBinary(sText)
    Base64Encode = oNode.text
    Set oNode = Nothing
    Set oXML = Nothing
End Function

Function Base64Decode(ByVal vCode)
    Dim oXML, oNode
    Set oXML = CreateObject("Msxml2.DOMDocument.3.0")
    Set oNode = oXML.CreateElement("base64")
    oNode.dataType = "bin.base64"
    oNode.text = vCode
    Base64Decode = Stream_BinaryToString(oNode.nodeTypedValue)
    Set oNode = Nothing
    Set oXML = Nothing
End Function

Private Function Stream_StringToBinary(Text)
  Const adTypeText = 2
  Const adTypeBinary = 1
  Dim BinaryStream 'As New Stream
  Set BinaryStream = CreateObject("ADODB.Stream")
  BinaryStream.Type = adTypeText
  BinaryStream.CharSet = "us-ascii"
  BinaryStream.Open
  BinaryStream.WriteText Text
  BinaryStream.Position = 0
  BinaryStream.Type = adTypeBinary
  BinaryStream.Position = 0
  Stream_StringToBinary = BinaryStream.Read
  Set BinaryStream = Nothing
End Function

Private Function Stream_BinaryToString(Binary)
  Const adTypeText = 2
  Const adTypeBinary = 1
  Dim BinaryStream 'As New Stream
  Set BinaryStream = CreateObject("ADODB.Stream")
  BinaryStream.Type = adTypeBinary
  BinaryStream.Open
  BinaryStream.Write Binary
  BinaryStream.Position = 0
  BinaryStream.Type = adTypeText
  BinaryStream.CharSet = "us-ascii"
  Stream_BinaryToString = BinaryStream.ReadText
  Set BinaryStream = Nothing
End Function
%>

@KarmaBlackshaw

Korean characters are converted into somewhat unreadable strings.

Dim encode
encode = Base64Encode("{""device"":""pc"",""user"":{""id"":10,""level"":1,""login_id"":""lorem29"",""login_name"":""회원가입신청"",""language"":""en""}}")

It returns

{"device":"pc","user":{"id":10,"level":1,"login_id":"lorem29","login_name":"isOi>?e??iz.i< i2-","language":"en"}}

Any idea why and how to solve this?

I use the Base64 class:
https://gist.github.com/domus71/f593fcc2fec3d9a4eb68fdf2034bf11d