# -*- coding:utf-8 -*-
def weijiniya_jiemi(ciphertext,key):
ascii='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
keylen=len(key)
ctlen=len(ciphertext)
plaintext = ''
i = 0
while i < ctlen:
j = i % keylen
k = ascii.index(key[j])
m = ascii.index(ciphertext[i])
if m < k:
m += 26
plaintext += ascii[m-k]
i += 1
print plaintext
def weijiniya_jiami(plaintext,key):
ascii='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
keylen=len(key)
ptlen=len(plaintext)
ciphertext = ''
i = 0
while i < ptlen:
j = i % keylen
k = ascii.index(key[j])
m = ascii.index(plaintext[i])
ciphertext += ascii[(m+k)%26]
i += 1
print ciphertext
def main():
print 'CHOICE:'
print '1:weijiniya_jiami'
print '2:weijiniya_jiemi'
choice = input()
if choice == 1:
plaintext = input('jiama_string1:')
key = input('key:')
weijiniya_jiami(plaintext,key)
elif choice == 2:
ciphertext = input('jiemi_string1:')
key = input('key:')
weijiniya_jiemi(ciphertext,key)
else:
print('error！')
main()
if __name__ == '__main__':
main()
好像cmd窗口有点问题，中文一直显示不出来，就直接用拼音了哈哈哈。。。
再加一个凯撒的，虽然直接有网址可以解：
# -*- coding:utf-8 -*-
defchange(c,i):
c = c.lower()
num =ord(c)
ifnum >=97andnum <=122:
num =97+ ((num -97) + i) %26
returnchr(num)
defkaisa_jiami(string,i):
string_new =''
forsinstring:
string_new += change(s,i)
print(string_new)
returnstring_new
defkaisa_jiemi(string):
foriinrange(25):
print('\n', i,'\n')
i +=1
kaisa_jiami(string,i)
defmain():
print('请选择需要的操作：')
print('1：凯撒加密')
print('2：凯撒解密')
choice =input()
ifchoice ==1:
string =input('请输入需要加密的字符串：')
num =int(input('请输入需要偏移的位数：'))
kaisa_jiami(string,num)
elifchoice ==2:
string =input('请输入需要解密的字符串：')
kaisa_jiemi(string)
else:
print('输入错误，请重试！')
main()
if__name__ =='__main__':
main()