Option Explicit
Option Base 0

Public Type MD5_CTX
    i(1) As Long
    buf(3) As Long
    inc(63) As Byte
    digest(15) As Byte
End Type

Public Declare Sub MD5Init Lib "Cryptdll.dll" (ByVal pContex As Long)
Public Declare Sub MD5Final Lib "Cryptdll.dll" (ByVal pContex As Long)
Public Declare Sub MD5Update Lib "Cryptdll.dll" (ByVal pContex As Long, ByVal lPtr As Long, ByVal nSize As Long)

Public Function ConvBytesToBinaryString(bytesIn() As Byte) As String
    Dim i As Long
    Dim nSize As Long
    Dim strRet As String
   
    nSize = UBound(bytesIn)
    For i = 0 To nSize
         strRet = strRet & Right$("0" & Hex(bytesIn(i)), 2)
    Next
    ConvBytesToBinaryString = strRet
End Function

Public Function GetMD5Hash(bytesIn() As Byte) As Byte()
    Dim ctx As MD5_CTX
    Dim nSize As Long
   
    nSize = UBound(bytesIn) + 1
   
    MD5Init VarPtr(ctx)
    MD5Update ByVal VarPtr(ctx), ByVal VarPtr(bytesIn(0)), nSize
    MD5Final VarPtr(ctx)
   
    GetMD5Hash = ctx.digest
End Function

Public Function GetMD5Hash_Bytes(bytesIn() As Byte) As String
    GetMD5Hash_Bytes = ConvBytesToBinaryString(GetMD5Hash(bytesIn))
End Function

Public Function GetMD5Hash_String(ByVal strIn As String) As String
    GetMD5Hash_String = GetMD5Hash_Bytes(StrConv(strIn, vbFromUnicode))
End Function

Public Function GetMD5Hash_File(ByVal strFile As String) As String
    Dim lFile As Long
    Dim bytes() As Byte
    Dim lSize As Long
   
    lSize = FileLen(strFile)
    If (lSize) Then
        lFile = FreeFile
        ReDim bytes(lSize - 1)
        Open strFile For Binary As lFile
        Get lFile, , bytes
        Close lFile
        GetMD5Hash_File = GetMD5Hash_Bytes(bytes)
    End If
End Function