Encoding to Base64

Base64 is an encoding scheme that represents data using 64 characters. It is commonly used in email, software, and web APIs.

In this example, we will show you how to convert text data to Base64 using VBA without any reference settings.

Source Code

'*-------------------------------------------------------------
'* Encode text to Base64
'*
'* @param text The value to be converted
'* @return Base64 formatted data
'*-------------------------------------------------------------
Public Function EncodeToBase64(ByRef text As String) As String

  ' Prepare the object
  Dim node As Object
  Set node = CreateObject("Msxml2.DOMDocument.3.0").createElement("base64")

  ' Encode
  node.DataType = "bin.base64"
  node.nodeTypedValue = ConvertToBinary(text)

  ' Remove line breaks that cannot be removed by the function and return
  EncodeToBase64 = Replace(node.text, vbLf, "")
End Function

'*-------------------------------------------------------------
'* Convert string to binary data
'*
'* @param text The value to be converted
'* @return Binary data
'*-------------------------------------------------------------
Public Function ConvertToBinary(ByRef text As String)

  ' Prepare the object
  Dim BinaryStream As Object
  Set BinaryStream = CreateObject("ADODB.Stream")

  ' Configure the Stream
  With BinaryStream
    .Type = 2
    .Charset = "us-ascii"
    .Open
    .WriteText text
    .Position = 0
    .Type = 1
    .Position = 0
  End With

  ConvertToBinary = BinaryStream.Read
End Function

Test Execution

Execution

Public Sub execute()
    Debug.Print (EncodeToBase64("aaa"))
    Debug.Print (EncodeToBase64("aab"))
    Debug.Print (EncodeToBase64("aac"))
End Sub

Result

YWFh
YWFi
YWFj

Additional Information about Base64

Base64 is an encoding scheme that allows handling multibyte characters and binary data in communication environments where only 64 printable alphanumeric characters can be used and other characters cannot be handled. It is defined by MIME and widely used in email, which can only handle 7-bit data. Specifically, it uses 62 characters from A-Z, a-z, 0-9, two symbols (+, /), and the symbol ”=” is used for padding (to fill the remaining part).

Base64 - Wikipedia

As mentioned above, Base64 is still widely used today, and there are also other encoding schemes such as Base16 and Base32.

Since it is defined by MIME, it is used in VBA when the MIME type of the API specifies Base64, for example.