'字符串加密
Function Encrypt(theNumber)
 On Error Resume Next
 Dim n, szEnc, t, HiN, LoN, i
 n = CDbl((theNumber + 1570) ^ 2 - 7 * (theNumber + 1570) - 450)
 If n < 0 Then szEnc = "R" Else szEnc = "J"
 n = CStr(abs(n))
 For i = 1 To Len(n) step 2
  t = Mid(n, i, 2)
  If Len(t) = 1 Then
   szEnc = szEnc & t
   Exit For
  End If
  HiN = (CInt(t) And 240) / 16
  LoN = CInt(t) And 15
  szEnc = szEnc & Chr(Asc("M") + HiN) & Chr(Asc("C") + LoN)
 Next
 Encrypt = szEnc
End Function

'字符串解密
Function Decrypt(theNumber)
 On Error Resume Next
 Dim e, n, sign, t, HiN, LoN, NewN, i
 e = theNumber
 If Left(e, 1) = "R" Then sign = -1 Else sign = 1
 e = Mid(e, 2)
 NewN = ""
 For i = 1 To Len(e) step 2
  t = Mid(e, i, 2)
  If Asc(t) >= Asc("0") And Asc(t) <= Asc("9") Then
   NewN = NewN & t
   Exit For
  End If
  HiN = Mid(t, 1, 1)
  LoN = Mid(t, 2, 1)
  HiN = (Asc(HiN) - Asc("M")) * 16
  LoN = Asc(LoN) - Asc("C")
  t = CStr(HiN Or LoN)
  If Len(t) = 1 Then t = "0" & t
  NewN = NewN & t
 Next
 e = CDbl(NewN) * sign
 Decrypt = CLng((7 + sqr(49 - 4 * (-450 - e))) / 2 - 1570)
End Function