Many thanks for sharing. Looks like it would be ideal for password encryption/decryption.
Adding to your fine work, here's a few more functions that are just wrappers:

Code:
Public Function EncodeBase85_FromStringToString(ByVal sourceData As String, Optional Add_bota_Header As Boolean = False) As String
 Dim B() As Byte
 EncodeBase85_FromStringToArray sourceData, B, Add_bota_Header
 EncodeBase85_FromStringToString = StrConv(B, vbUnicode)
End Function
Public Function EncodeBase85_FromArrayToString(sourceData() As Byte, Optional Add_bota_Header As Boolean = True) As String
 Dim B() As Byte
 EncodeBase85_FromArrayToArray sourceData, B, Add_bota_Header
 EncodeBase85_FromArrayToString = StrConv(B, vbUnicode)
End Function
Public Function DecodeBase85_FromArrayToString(sourceData() As Byte) As String
 Dim B() As Byte
 DecodeBase85_FromArrayToArray sourceData, B
 DecodeBase85_FromArrayToString = StrConv(B, vbUnicode)
End Function
Public Function DecodeBase85_FromStringToString(sourceData As String) As String
 Dim B() As Byte
 DecodeBase85_FromStringToArray sourceData, B
 DecodeBase85_FromStringToString = StrConv(B, vbUnicode)
End Function