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vb.net的md5加密 vb加密程序代码例题

IT技术加密

怎么在.net上实现MD5crypt的加密（最好vb.net代码）MD5实际一种单向的算法 ， 是散列，很多人认为是加密，实际有误
比如说winxp、win7各版本都有MD5值，那么是否可依据这个值还原出个正版的winxp或win7呢？
况且MD5“加密”的密钥长度又是多少呢?比如des的不同版本有64位、128位、192位等
用VB实现MD5加密md5加密运算是不可逆的，就是说不能通过那一串古古怪怪的东西算出它原始的样子 。
以下提供VB可用的16位和32位MD5加密函数代码：
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 iShiftBits0 Or iShiftBits31 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
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 iShiftBits0 Or iShiftBits31 Then
Err.Raise 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 Function
Private Function md5_I(x, y, z)
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)
a = AddUnsigned(a, b)
End Sub
Private Sub md5_GG(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_G(b, c, d), x), ac))
a = RotateLeft(a, s)
a = AddUnsigned(a, b)
End Sub
Private Sub md5_HH(a, b, c, d, x, s, ac)
a = AddUnsigned(a, AddUnsigned(AddUnsigned(md5_H(b, c, d), x), 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

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