凯撒密码，求求孩子吧，单独可以加密解密，放在一起就乱码了，求原因？

Str1 = input()
for i in range(0,len(Str)):
    if Str[i] ==' ':
        print(' ', end="")
    elif Str[i] in ['x', 'y', 'z']:
        print(chr(ord(Str[i])-23),end='')
    else:
        print(chr(ord(Str[i])+3),end='')
    elif Str[i] in ['a','b','c']:
        print(chr(ord(Str[i])+23),end='')
    else:
        print(chr(ord(Str[i])-3),end='')

凯撒密码是个啥规则？看你的代码，总觉的是缩进有问题

#!/usr/bin/env python 
# -*- coding: utf-8 -*- 

upperDict=['A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z']
lowerDict=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

def cesarWithLetter(ciphertext,offset):
    '''
    凯撒密码 :
        只转换字母(包括大写小写)
    参数 : 
        ciphertext : 明文
        offset : 偏移量
    '''
    result = ""
    for ch in ciphertext:
        if ch.isupper():
            result=result+upperDict[((upperDict.index(ch)+offset)%26)]
        elif ch.islower():
            result=result+lowerDict[((lowerDict.index(ch)+offset)%26)]
        elif ch.isdigit():
            result=result+ch
        else:
            result=result+ch
    return result

def printAllResult(ciphertext):
    '''
    打印所有偏移结果
    '''
    for i in range(len(upperDict)):
        print cesarWithLetter(ciphertext,i)

ciphertext=input("Please input the words : ")
printAllResult(ciphertext)