python实现移位加密和解密

def encrypt():
  temp = raw_input("Please input your sentence: ")
  key = int(raw_input("Please input your key: "))
  listA = map(ord,temp)
  lens = len(listA)
  for i in range(lens):
    a = listA[i]
    if 65 <= a <= 90:
      a += key
      while a > 90:
        a -= 26
    elif 97 <= a <= 122:
      a += key
      while a > 122:
        a -= 26
    listA[i] = a
  listA = map(chr,listA)
  listA = ''.join(listA)
  print listA


def unencrypt():
  temp = raw_input("Please input your sentence: ")
  key = int(raw_input("Please input your key: "))
  listA = map(ord, temp)
  lens = len(listA)

  for i in range(lens):
    a = listA[i]
    if 65 <= a <= 90:
      a -= key
      while a < 65:
        a += 26
    elif 97 <= a <= 122:
      a -= key
      while a < 97:
        a += 26
    listA[i] = a
  listA = map(chr, listA)
  listA = ''.join(listA)
  print listA


a = int(raw_input("input 0 to encrypt and 1 to unencrypt"))

if a == 0:
  encrypt()
elif a == 1:
  unencrypt()