经典加密算法在VB中的实现：MD5

　Option Explicit
　　Dim w1 As String, w2 As String, w3 As String, w4 As String
　　Function MD5F(ByVal tempstr As String, ByVal w As String, ByVal X As S
　　tring, ByVal y As String, ByVal z As String, ByVal Xin As String, ByVa
　　l qdata As String, ByVal rots As Integer)
　　MD5F = BigMod32Add(RotLeft(BigMod32Add(BigMod32Add(w, tempstr), Bi
　　gMod32Add(Xin, qdata)), rots), X)
　　End Function
　　Sub MD5F1(w As String, ByVal X As String, ByVal y As String, ByVal z A
　　s String, ByVal Xin As String, ByVal qdata As String, ByVal rots As In
　　teger)
　　Dim tempstr As String
　　tempstr = BigXOR(z, BigAND(X, BigXOR(y, z)))
　　w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
　　End Sub
　　Sub MD5F2(w As String, ByVal X As String, ByVal y As String, ByVal z A
　　s String, ByVal Xin As String, ByVal qdata As String, ByVal rots As In
　　teger)
　　Dim tempstr As String
　　tempstr = BigXOR(y, BigAND(z, BigXOR(X, y)))
　　w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
　　End Sub
　　Sub MD5F3(w As String, ByVal X As String, ByVal y As String, ByVal z A
　　s String, ByVal Xin As String, ByVal qdata As String, ByVal rots As In
　　teger)
　　Dim tempstr As String
　　tempstr = BigXOR(X, BigXOR(y, z))
　　w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
　　End Sub
　　Sub MD5F4(w As String, ByVal X As String, ByVal y As String, ByVal z A
　　s String, ByVal Xin As String, ByVal qdata As String, ByVal rots As In
　　teger)
　　Dim tempstr As String
　　tempstr = BigXOR(y, BigOR(X, BigNOT(z)))
　　w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
　　End Sub
　　Function MD5_Calc(ByVal hashthis As String) As String
　　ReDim buf(0 To 3) As String
　　ReDim Xin(0 To 15) As String
　　Dim tempnum As Integer, tempnum2 As Integer, loopit As Integer, loopou
　　ter As Integer, loopinner As Integer
　　Dim a As String, b As String, c As String, d As String
　　 Add padding
　　tempnum = 8 * Len(hashthis)
　　hashthis = hashthis + Chr$(128) Add binary 10000000
　　tempnum2 = 56 - Len(hashthis) Mod 64
　　If tempnum2 < 0 Then
　　tempnum2 = 64 + tempnum2
　　End If
　　hashthis = hashthis + String$(tempnum2, Chr$(0))
　　For loopit = 1 To 8
　　hashthis = hashthis + Chr$(tempnum Mod 256)
　　tempnum = tempnum - tempnum Mod 256
　　tempnum = tempnum / 256
　　Next loopit
　　 Set magic numbers
　　buf(0) = "67452301"
　　buf(1) = "efcdab89"
　　buf(2) = "98badcfe"
　　buf(3) = "10325476"
　　 For each 512 bit section
　　For loopouter = 0 To Len(hashthis) / 64 - 1
　　a = buf(0)
　　b = buf(1)
　　c = buf(2)
　　d = buf(3)
　　 Get the 512 bits
　　For loopit = 0 To 15
　　Xin(loopit) = ""
　　For loopinner = 1 To 4
　　Xin(loopit) = Hex$(Asc(Mid$(hashthis, 64 * loopouter +
　　4 * loopit + loopinner, 1))) + Xin(loopit)
　　If Len(Xin(loopit)) Mod 2 Then Xin(loopit) = "0" + Xin
　　(loopit)
　　Next loopinner
　　Next loopit
　　 Round 1

　MD5F1 a, b, c, d, Xin(0), "d76aa478", 7
　　MD5F1 d, a, b, c, Xin(1), "e8c7b756", 12
　　MD5F1 c, d, a, b, Xin(2), "242070db", 17
　　MD5F1 b, c, d, a, Xin(3), "c1bdceee", 22
　　MD5F1 a, b, c, d, Xin(4), "f57c0faf", 7
　　MD5F1 d, a, b, c, Xin(5), "4787c62a", 12
　　MD5F1 c, d, a, b, Xin(6), "a8304613", 17
　　MD5F1 b, c, d, a, Xin(7), "fd469501", 22
　　MD5F1 a, b, c, d, Xin(8), "698098d8", 7
　　MD5F1 d, a, b, c, Xin(9), "8b44f7af", 12
　　MD5F1 c, d, a, b, Xin(10), "ffff5bb1", 17
　　MD5F1 b, c, d, a, Xin(11), "895cd7be", 22
　　MD5F1 a, b, c, d, Xin(12), "6b901122", 7
　　MD5F1 d, a, b, c, Xin(13), "fd987193", 12
　　MD5F1 c, d, a, b, Xin(14), "a679438e", 17
　　MD5F1 b, c, d, a, Xin(15), "49b40821", 22
　　 Round 2
　　MD5F2 a, b, c, d, Xin(1), "f61e2562", 5
　　MD5F2 d, a, b, c, Xin(6), "c040b340", 9
　　MD5F2 c, d, a, b, Xin(11), "265e5a51", 14
　　MD5F2 b, c, d, a, Xin(0), "e9b6c7aa", 20
　　MD5F2 a, b, c, d, Xin(5), "d62f105d", 5
　　MD5F2 d, a, b, c, Xin(10), "02441453", 9
　　MD5F2 c, d, a, b, Xin(15), "d8a1e681", 14
　　MD5F2 b, c, d, a, Xin(4), "e7d3fbc8", 20
　　MD5F2 a, b, c, d, Xin(9), "21e1cde6", 5
　　MD5F2 d, a, b, c, Xin(14), "c33707d6", 9
　　MD5F2 c, d, a, b, Xin(3), "f4d50d87", 14
　　MD5F2 b, c, d, a, Xin(8), "455a14ed", 20
　　MD5F2 a, b, c, d, Xin(13), "a9e3e905", 5
　　MD5F2 d, a, b, c, Xin(2), "fcefa3f8", 9
　　MD5F2 c, d, a, b, Xin(7), "676f02d9", 14
　　MD5F2 b, c, d, a, Xin(12), "8d2a4c8a", 20
　　 Round 3
　　MD5F3 a, b, c, d, Xin(5), "fffa3942", 4
　　MD5F3 d, a, b, c, Xin(8), "8771f681", 11
　　MD5F3 c, d, a, b, Xin(11), "6d9d6122", 16
　　MD5F3 b, c, d, a, Xin(14), "fde5380c", 23
　　MD5F3 a, b, c, d, Xin(1), "a4beea44", 4
　　MD5F3 d, a, b, c, Xin(4), "4bdecfa9", 11
　　MD5F3 c, d, a, b, Xin(7), "f6bb4b60", 16
　　MD5F3 b, c, d, a, Xin(10), "bebfbc70", 23
　　MD5F3 a, b, c, d, Xin(13), "289b7ec6", 4
　　MD5F3 d, a, b, c, Xin(0), "e27fa", 11
　　MD5F3 c, d, a, b, Xin(3), "d4ef3085", 16
　　MD5F3 b, c, d, a, Xin(6), "04881d05", 23
　　MD5F3 a, b, c, d, Xin(9), "d9d4d039", 4
　　MD5F3 d, a, b, c, Xin(12), "e6db99e5", 11
　　MD5F3 c, d, a, b, Xin(15), "1fa27cf8", 16
　　MD5F3 b, c, d, a, Xin(2), "c4ac5665", 23
　　 Round 4
　　MD5F4 a, b, c, d, Xin(0), "f4292244", 6
　　MD5F4 d, a, b, c, Xin(7), "432aff97", 10
　　MD5F4 c, d, a, b, Xin(14), "ab9423a7", 15
　　MD5F4 b, c, d, a, Xin(5), "fc93a039", 21
　　MD5F4 a, b, c, d, Xin(12), "655b59c3", 6
　　MD5F4 d, a, b, c, Xin(3), "8f0ccc92", 10
　　MD5F4 c, d, a, b, Xin(10), "ffeff47d", 15
　　MD5F4 b, c, d, a, Xin(1), "85845dd1", 21
　　MD5F4 a, b, c, d, Xin(8), "6fa87e4f", 6
　　MD5F4 d, a, b, c, Xin(15), "fe2ce6e0", 10
　　MD5F4 c, d, a, b, Xin(6), "a3014314", 15
　　MD5F4 b, c, d, a, Xin(13), "4e0811a1", 21
　　MD5F4 a, b, c, d, Xin(4), "f7537e82", 6
　　MD5F4 d, a, b, c, Xin(11), "bd3af235", 10
　　MD5F4 c, d, a, b, Xin(2), "2ad7d2bb", 15
　　MD5F4 b, c, d, a, Xin(9), "eb86d391", 21
　　buf(0) = BigAdd(buf(0), a)
　　buf(1) = BigAdd(buf(1), b)
　　buf(2) = BigAdd(buf(2), c)
　　buf(3) = BigAdd(buf(3), d)
　　Next loopouter Extract MD5Hash
　　hashthis = ""
　　For loopit = 0 To 3
　　For loopinner = 3 To 0 Step -1
　　hashthis = hashthis + Chr(Val("&H" + Mid$(buf(loopit), 1 +
　　2 * loopinner, 2)))
　　Next loopinner
　　Next loopit
　　 And return it
　　MD5_Calc = hashthis
　　End Function
　　Function BigMod32Add(ByVal value1 As String, ByVal value2 As String) A
　　s String
　　BigMod32Add = Right$(BigAdd(value1, value2), 8)
　　End Function
　　Public Function BigAdd(ByVal value1 As String, ByVal value2 As String)
　　As String
　　Dim valueans As String
　　Dim loopit As Integer, tempnum As Integer
　　tempnum = Len(value1) - Len(value2)
　　If tempnum < 0 Then
　　value1 = Space$(Abs(tempnum)) + value1
　　ElseIf tempnum > 0 Then
　　value2 = Space$(Abs(tempnum)) + value2
　　End If
　　tempnum = 0
　　For loopit = Len(value1) To 1 Step -1
　　tempnum = tempnum + Val("&H" + Mid$(value1, loopit, 1)) + Val(
　　"&H" + Mid$(value2, loopit, 1))
　　valueans = Hex$(tempnum Mod 16) + valueans
　　tempnum = Int(tempnum / 16)
　　Next loopit
　　If tempnum <> 0 Then
　　valueans = Hex$(tempnum) + valueans
　　End If
　　BigAdd = Right(valueans, 8)
　　End Function
　　Public Function RotLeft(ByVal value1 As String, ByVal rots As Integer)
　　As String
　　Dim tempstr As String
　　Dim loopit As Integer, loopinner As Integer
　　Dim tempnum As Integer
　　rots = rots Mod 32
　　If rots = 0 Then
　　RotLeft = value1
　　Exit Fu