MD5算法 vb......

MD5 算法

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 = 0

End If

Exit Function

ElseIf iShiftBits < 0 or iShiftBits > 31 Then

Err.Raise 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

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

Err.Raise 6

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))

Private Function AddUnsigned(lX, lY)

Dim lX4

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

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

md5_I = (y Xor (x or (Not z)))

End Function

Private Sub md5_FF(a, b, c, d, x, s, ac)

a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_F(b, c, d), x), ac))

a = RotateLeft(a, s)

End Sub

Private Sub md5_GG(a, b, c, d, x, s, ac)

a = RotateLeft(a, s)

a = AddUnsigned(a, b)

End Sub

Private Sub md5_II(a, b, c, d, x, s, ac)

a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_I(b, c, d), x), ac))

a = RotateLeft(a, s)

a = AddUnsigned(a, b)

End Sub

Private Function ConvertToWordArray(sMessage)

Dim lMessageLength

Const MODULUS_BITS = 512

Const CONGRUENT_BITS = 448

lMessageLength = Len(sMessage)

lNumberOfWords = (((lMessageLength + ((MODULUS_BITS - CONGRUENT_BITS) \

BITS_TO_A_BYTE)) \ (MODULUS_BITS \ BITS_TO_A_BYTE)) + 1) * (MODULUS_BITS

\ BITS_TO_A_WORD)

ReDim lWordArray(lNumberOfWords - 1)