一個簡單實用的 vb 加密/解密演算法 (轉)

一個簡單實用的 vb 加密/解密演算法 (轉)[@more@]

Function UserCode(pass As String) As String
'口令
  Dim il_bit, il_x, il_y, il_z, il_len, i As Long
  Dim is_out As String
  il_len = Len(password)
  il_x = 0
  il_y = 0
  is_out = ""
  For i = 1 To il_len
  il_bit = AscW(Mid(password, i, 1))  'W系列支援unicode
 
  il_y = (il_bit * 13 Mod 256) + il_x
  is_out = is_out & ChrW(Fix(il_y))  '取整 int和fix區別: fix修正負數
  il_x = il_bit * 13 / 256
  Next
  is_out = is_out & ChrW(Fix(il_x))
 
  password = is_out
  il_len = Len(password)
  il_x = 0
  il_y = 0
  is_out = ""
  For i = 1 To il_len
  il_bit = AscW(Mid(password, i, 1))
  '取前4位值
  il_y = il_bit / 16 + 64
  is_out = is_out & ChrW(Fix(il_y))
  '取後4位值
  il_y = (il_bit Mod 16) + 64
  is_out = is_out & ChrW(Fix(il_y))
  Next
  UserCode = is_out
End Function
Function UserDeCode(password As String) As String
'口令
  Dim is_out As String
  Dim il_x, il_y, il_len, i, il_bit As Long

  il_len = Len(password)
  il_x = 0
  il_y = 0
  is_out = ""
  For i = 1 To il_len Step 2
  il_bit = AscW(Mid(password, i, 1))
  '取前4位值
  il_y = (il_bit - 64) * 16
  '取後4位值
  'dd = AscW(Mid(password, i + 1, 1)) - 64
  il_y = il_y + AscW(Mid(password, i + 1, 1)) - 64
  is_out = is_out & ChrW(il_y)
  Next

  il_x = 0
  il_y = 0
  password = is_out
  is_out = ""

  il_len = Len(password)
  il_x = AscW(Mid(password, il_len, 1)) 

  For i = (il_len - 1) To 1 Step -1
  il_y = il_x * 256 + AscW(Mid(password, i, 1))
  il_x = il_y Mod 13
  is_out = ChrW(Fix(il_y / 13)) & is_out
  Next
  UserDeCode = is_out
End Function