Caesar加密与解密

本文讲述的是加密方式的一种：Caesar加密和解密

Caesar cipher（恺撒密码）

def takelock(str,offset):
    res = ''
    for char in str:
        if 'a' <= char <= 'z':
            res += chr( ord('a') + ((ord(char) - ord('a'))+offset)%26 )
        elif 'A' <= char <='Z':
            res += chr( ord('A') + ((ord(char) - ord('A'))+offset)%26 )
        else:
            res += char
    return res

def unlock(str,offset):
    res = ''
    for char in str:
        if 'a' <= char <= 'z':
            res += chr( ord('a') + (ord(char) - ord('a') - offset) % 26 )
        elif 'A' <= char <= 'Z':
            res += chr( ord('A') + (ord(char) - ord('A') - offset) % 26)
    return res

if __name__ == '__main__':
    while True:
        strs = input('输入str :  ')
        offset = input('输入offset :  ')
        print(takelock(strs,int(offset)))
        strs = input('待解密str :  ')
        offset = input('输入offset :  ')
        print(unlock(strs,int(offset)))
        print('-----------------------------------------------------------------')