Python rot13加密

http://zh.wikipedia.org/wiki/ROT13

 

def rot13(s, OffSet=13):
     def encodeCh(ch):
         f=lambda x: chr((ord(ch)-x+OffSet) % 26 + x)
         return f(97) if ch.islower() else (f(65) if ch.isupper() else ch)
     return ''.join(encodeCh(c) for c in s)
 
 s='Hello!'
 print rot13(s)              # Uryyb!
 print rot13(rot13(s))       # Hello!
 print rot13(s,26)           # Hello!

 

def rot13_2(s,offSet=13):
    d={chr(i+c) : chr((i+offSet) % 26 + c) for i in range(26) for c in (65,97)}
    return ''.join([d.get(c, c) for c in s])