base64.bas

' http://web.archive.org/web/20060527094535/http://www.nonhostile.com/howto-encode-decode-base64-vb6.asp
' http://cwestblog.com/2013/09/23/vbscript-convert-image-to-base-64/

Public Function ConvertFileToBase64(strFilePath As String) As String

    Const UseBinaryStreamType = 1

    Dim streamInput: Set streamInput = CreateObject("ADODB.Stream")
    Dim xmlDoc: Set xmlDoc = CreateObject("Microsoft.XMLDOM")
    Dim xmlElem: Set xmlElem = xmlDoc.createElement("tmp")
    
    streamInput.Open
    streamInput.Type = UseBinaryStreamType
    streamInput.LoadFromFile strFilePath
    xmlElem.dataType = "bin.base64"
    xmlElem.nodeTypedValue = streamInput.Read
    ConvertFileToBase64 = Replace(xmlElem.Text, vbLf, "")
    
    Set streamInput = Nothing
    Set xmlDoc = Nothing
    Set xmlElem = Nothing
    
End Function

Public Sub ConvertBase64ToFile(strFilePath As String, strBase64 As String)

    Const UseBinaryStreamType = 1
    Const SaveWillCreateOrOverwrite = 2

    Dim streamOutput: Set streamOutput = CreateObject("ADODB.Stream")
    Dim xmlDoc: Set xmlDoc = CreateObject("Microsoft.XMLDOM")
    Dim xmlElem: Set xmlElem = xmlDoc.createElement("tmp")
    
    xmlElem.dataType = "bin.base64"
    xmlElem.Text = strBase64
    streamOutput.Open
    streamOutput.Type = UseBinaryStreamType
    streamOutput.Write = xmlElem.nodeTypedValue
    streamOutput.SaveToFile strFilePath, SaveWillCreateOrOverwrite
    
    Set streamOutput = Nothing
    Set xmlDoc = Nothing
    Set xmlElem = Nothing
    
End Sub