Python实现密钥密码（加解密）实例详解

'''
如密钥短语密码为: university -> universty
明文: abcdefghijklmnopqrstuvwxyz
密文：jklmopqwxzuniverstyabcdfgh
'''

# 构造映射 asc ---> crypt
def dic(x):
  list_x =[]
  list_z = []
  for i in x:
    list_x.append(ord(i))
  for i in range(97,123):
    if i not in list_x:
      list_x.append(i)
  list_ = list_x[26-len(x)-1:]
  cr = list_+list_x[:26-len(list_)]
  for i in range(97,123):
    list_z.append(i)
  return dict(map(lambda x,y:[x,y],list_z,cr))


# 构造映射 crypt ---> asc
def dic_2(x):
  list_x =[]
  list_z = []
  for i in x:
    list_x.append(ord(i))
  for i in range(97,123):
    if i not in list_x:
      list_x.append(i)
  list_ = list_x[26-len(x)-1:]
  cr = list_+list_x[:26-len(list_)]
  for i in range(97,123):
    list_z.append(i)
  return dict(map(lambda x,y:[x,y],cr,list_z))

# 密钥去重
def remove(x):
  unique_x = []
  for i in x:
    if i not in unique_x:
      unique_x.append(i)
  return unique_x

# 加密
def encode():
  x = input('请输入密钥字符：')
  if not x.isalpha():
    print('请输入正确的密钥格式！')
    exit(0)
  s = input('请输入明文：')
  print('加密后字符：',end='')
  unique_x = remove(x)
  dic_ = dic(unique_x)
  for i in s:
    if i.isspace():
      print(' ', end='')
    else:
      print(chr(dic_[ord(i)]),end='')


# 解密
def decode():
  x = input('请输入密钥字符：')
  if not x.isalpha():
    print('请输入正确的密钥格式！')
    exit(0)
  s = input('请输入密文：')
  print('解密后字符：',end='')
  unique_x = remove(x)
  dic_ = dic_2(unique_x)
  for i in s:
    if i.isspace():
      print(' ',end='')
    else:
      print(chr(dic_[ord(i)]),end='')

# 输入指令
answer = input(f'请输入所需的操作：编码/E or 解码/D: ')
try:
  if answer.upper() == 'E':
    encode()
  elif answer.upper() == 'D':
    decode()
  else:
    print('输入错误！')
except KeyError:
  print('请正确输入小写字母！')