MD5加密.doc

MD5 加密<% PRivate Const BITS_TO_A_BYTE =8 Private Const BYTES_TO_A_Word =4 Private Const BITS_TO_A_WORD = 32 Private m_lOnBits(30) Private m_l2Power(30) Private Function LShift(lValue, iShiftBits) If iShiftBits =0 Then LShift = lValue Exit Function ElseIf iShiftBits = 31 Then If lValue And 1 Then LShift = &H80000000 Else LShift =0 End If Exit Function ElseIf iShiftBits <0 Or iShiftBits > 31 Then 6 End If If (lValue And m_l2Power(31 - iShiftBits)) Then LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000 Else LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits)) End If End Function Private Function RShift(lValue, iShiftBits) If iShiftBits =0 Then RShift = lValue Exit Function ElseIf iShiftBits = 31 Then If lValue And &H80000000 Then RShift =1 Else RShift =0 End If Exit Function ElseIf iShiftBits <0 Or iShiftBits > 31 Then 6 End If RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits) If (lValue And &H80000000) Then RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1))) End If End Function Private Function RotateLeft(lValue, iShiftBits) RotateLeft = LShift(lValue, iShiftBits) Or RShift(lValue, (32 - iShiftBits)) End Function Private Function AddUnsigned(lX, lY) Dim lX4 Dim lY4 Dim lX8 Dim lY8 Dim lResult 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 Private Function md5_F(x, y, z) md5_F = (x And y) Or ((Not x) And z) End Function Private Function md5_G(x, y, z) md5_G = (x And z) Or (y And (Not z)) End Function Private Function md5_H(x, y, z) md5_H = (x Xor y Xor z) End