cmd5.cls

VB、ASP、JS、VBS中使用MD5的模組 很實用喔！

        Err.Raise 6
    End If
    
    ' We do not care about the top most bit or the final bit, the top most bit
    ' will be taken into account in the next stage, the final bit (whether it
    ' is an odd number or not) is being shifted into, so we do not give a jot
    ' about it
    RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits)
    
    ' If the top most bit (&H80000000) was set we need to do things differently
    ' as in a normal VB signed long integer the top most bit is used to indicate
    ' the sign of the number, when it is set it is a negative number, so just
    ' deviding by a factor of 2 as above would not work.
    ' NOTE: (lValue And  &H80000000) is equivalent to (lValue < 0), you could
    ' get a very marginal speed improvement by changing the test to (lValue < 0)
    If (lValue And &H80000000) Then
        ' We take the value computed so far, and then add the left most negative
        ' bit after it has been shifted to the right the appropriate number of
        ' places
        RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1)))
    End If
End Function

'*******************************************************************************
' RShiftSigned (FUNCTION)
'
' PARAMETERS:
' (In) - lValue     - Long    -
' (In) - iShiftBits - Integer -
'
' RETURN VALUE:
' Long -
'
' DESCRIPTION:
' The right shift of a signed long integer involves shifting all the set bits to
' the right and in-filling on the left with the sign bit (0 if positive, 1 if
' negative. This function is equivalent to the >> operator in Java or the >>
' operator in C++ when used on a signed long integer. Not used in this class,
' but included for completeness.
'*******************************************************************************
Private Function RShiftSigned(ByVal lValue As Long, _
                              ByVal iShiftBits As Integer) As Long
    
    ' NOTE: If you can guarantee that the Shift parameter will be in the
    ' range 1 to 30 you can safely strip of this first nested if structure for
    ' speed.
    '
    ' A shift of zero is no shift at all
    If iShiftBits = 0 Then
        RShiftSigned = lValue
        Exit Function
    
    ' A shift of 31 will clear all bits if the left most bit was zero, and will
    ' set all bits if the left most bit was 1 (a negative indicator)
    ElseIf iShiftBits = 31 Then
        
        ' NOTE: (lValue And  &H80000000) is equivalent to (lValue < 0), you
        ' could get a very marginal speed improvement by changing the test to
        ' (lValue < 0)
        If (lValue And &H80000000) Then
            RShiftSigned = -1
        Else
            RShiftSigned = 0
        End If
        Exit Function
    
    ' A shift of less than zero or more than 31 is undefined
    ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
        Err.Raise 6
    End If
    
    ' We get the same result by dividing by the appropriate power of 2 and
    ' rounding in the negative direction
    RShiftSigned = Int(lValue / m_l2Power(iShiftBits))
End Function

'*******************************************************************************
' RotateLeft (FUNCTION)
'
' PARAMETERS:
' (In) - lValue     - Long    - Value to act on
' (In) - iShiftBits - Integer - Bits to move by
'
' RETURN VALUE:
' Long - Result
'
' DESCRIPTION:
' Rotates the bits in a long integer to the left, those bits falling off the
' left edge are put back on the right edge
'*******************************************************************************
Private Function RotateLeft(ByVal lValue As Long, _
                            ByVal iShiftBits As Integer) As Long
    RotateLeft = LShift(lValue, iShiftBits) Or RShift(lValue, (32 - iShiftBits))
End Function

'*******************************************************************************
' AddUnsigned (FUNCTION)
'
' PARAMETERS:
' (In) - lX - Long - First value
' (In) - lY - Long - Second value
'
' RETURN VALUE:
' Long - Result
'
' DESCRIPTION:
' Adds two potentially large unsigned numbers without overflowing
'*******************************************************************************
Private Function AddUnsigned(ByVal lX As Long, _
                             ByVal lY As Long) As Long
    Dim lX4     As Long
    Dim lY4     As Long
    Dim lX8     As Long
    Dim lY8     As Long
    Dim lResult As Long
 
    lX8 = lX And &H80000000
    lY8 = lY And &H80000000
    lX4 = lX And &H40000000
    lY4 = lY And &H40000000
 
    lResult = (lX And &H3FFFFFFF) + (lY And &H3FFFFFFF)
 
    If lX4 And lY4 Then
        lResult = lResult Xor &H80000000 Xor lX8 Xor lY8
    ElseIf lX4 Or lY4 Then
        If lResult And &H40000000 Then
            lResult = lResult Xor &HC0000000 Xor lX8 Xor lY8
        Else
            lResult = lResult Xor &H40000000 Xor lX8 Xor lY8
        End If
    Else
        lResult = lResult Xor lX8 Xor lY8
    End If
 
    AddUnsigned = lResult
End Function

'*******************************************************************************
' F (FUNCTION)
'
' DESCRIPTION:
' MD5's F function
'*******************************************************************************
Private Function F(ByVal x As Long, _
                   ByVal y As Long, _
                   ByVal z As Long) As Long
    F = (x And y) Or ((Not x) And z)
End Function

'*******************************************************************************
' G (FUNCTION)
'
' DESCRIPTION:
' MD5's G function
'*******************************************************************************
Private Function G(ByVal x As Long, _
                   ByVal y As Long, _
                   ByVal z As Long) As Long
    G = (x And z) Or (y And (Not z))
End Function

'*******************************************************************************
' H (FUNCTION)
'
' DESCRIPTION:
' MD5's H function
'*******************************************************************************
Private Function H(ByVal x As Long, _
                   ByVal y As Long, _
                   ByVal z As Long) As Long
    H = (x Xor y Xor z)
End Function

'*******************************************************************************
' I (FUNCTION)
'
' DESCRIPTION:
' MD5's I function
'*******************************************************************************
Private Function I(ByVal x As Long, _
                   ByVal y As Long, _
                   ByVal z As Long) As Long
    I = (y Xor (x Or (Not z)))
End Function

'*******************************************************************************
' FF (SUB)
'
' DESCRIPTION:
' MD5's FF procedure
'*******************************************************************************
Private Sub FF(a As Long, _
               ByVal b As Long, _
               ByVal c As Long, _
               ByVal d As Long, _
               ByVal x As Long, _
               ByVal s As Long, _
               ByVal ac As Long)
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(F(b, c, d), x), ac))
    a = RotateLeft(a, s)
    a = AddUnsigned(a, b)
End Sub

'*******************************************************************************
' GG (SUB)
'
' DESCRIPTION:
' MD5's GG procedure
'*******************************************************************************
Private Sub GG(a As Long, _
               ByVal b As Long, _
               ByVal c As Long, _
               ByVal d As Long, _
               ByVal x As Long, _
               ByVal s As Long, _
               ByVal ac As Long)
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(G(b, c, d), x), ac))
    a = RotateLeft(a, s)
    a = AddUnsigned(a, b)
End Sub

'*******************************************************************************
' HH (SUB)
'
' DESCRIPTION:
' MD5's HH procedure
'*******************************************************************************
Private Sub HH(a As Long, _
               ByVal b As Long, _
               ByVal c As Long, _
               ByVal d As Long, _
               ByVal x As Long, _
               ByVal s As Long, _
               ByVal ac As Long)
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(H(b, c, d), x), ac))
    a = RotateLeft(a, s)
    a = AddUnsigned(a, b)
End Sub

'*******************************************************************************
' II (SUB)
'
' DESCRIPTION:
' MD5's II procedure
'*******************************************************************************
Private Sub II(a As Long, _
               ByVal b As Long, _
               ByVal c As Long, _
               ByVal d As Long, _
               ByVal x As Long, _
               ByVal s As Long, _
               ByVal ac As Long)
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(I(b, c, d), x), ac))