VB中实现MD5加密

p;  value = (value And &H3FFFFFFF) * 2
        value = value Or ((lngSign < 0) And 1) Or (CBool(lngSign And _
                &H40000000) And &H80000000)
    Next
    LongLeftRotate = value
End Function

''
'' Function to add two unsigned numbers together as in C.
'' Overflows are ignored!
''
Private Function LongOverflowAdd(Val1 As Long, Val2 As Long) As Long
    Dim lngHighWord As Long
    Dim lngLowWord As Long
    Dim lngOverflow As Long

    lngLowWord = (Val1 And &HFFFF&) + (Val2 And &HFFFF&)
    lngOverflow = lngLowWord \ 65536
    lngHighWord = (((Val1 And &HFFFF0000) \ 65536) + ((Val2 And &HFFFF0000) \ 65536) + lngOverflow) And &HFFFF&
    LongOverflowAdd = UnsignedToLong((lngHighWord * 65536#) + (lngLowWord And &HFFFF&))
End Function

''
'' Function to add two unsigned numbers together as in C.
'' Overflows are ignored!
''
Private Function LongOverflowAdd4(Val1 As Long, Val2 As Long, val3 As Long, val4 As Long) As Long
    Dim lngHighWord As Long
    Dim lngLowWord As Long
    Dim lngOverflow As Long

    lngLowWord = (Val1 And &HFFFF&) + (Val2 And &HFFFF&) + (val3 And &HFFFF&) + (val4 And &HFFFF&)
    lngOverflow = lngLowWord \ 65536
    lngHighWord = (((Val1 And &HFFFF0000) \ 65536) + _
                   ((Val2 And &HFFFF0000) \ 65536) + _
                   ((val3 And &HFFFF0000) \ 65536) + _
                   ((val4 And &HFFFF0000) \ 65536) + _
                   lngOverflow) And &HFFFF&
    LongOverflowAdd4 = UnsignedToLong((lngHighWord * 65536#) + (lngLowWord And &HFFFF&))
End Function

''
'' Convert an unsigned double into a long
''
Private Function UnsignedToLong(value As Double) As Long
        If value < 0 Or value >= OFFSET_4 Then Error 6 '' Overflow
        If value <= MAXINT_4 Then
          UnsignedToLong = value
        Else
          UnsignedToLong = value - OFFSET_4
       &nbs