Шифрование и дешифрование. Не могу найти ошибку

import string
 
a=input("Enter the message->")
text_plain=a
 
key=input("Enter the key ->")
key=[int(v)for v in key]
print(key)
 
rep=len(text_plain)//len(key)
residue=len(text_plain)%len(key)
print("len_text_plain=",len(text_plain),"rep=", rep, "residue=", residue)
key=key*rep+key[:residue]
print("key=", key,"len_key=", len(key))
 
text_cipher=""
 
for i,letter in enumerate(text_plain):
    
    if letter in string.ascii_uppercase:
        code_cipher=ord(letter)+key[i]
        if code_cipher>90:
            code_cipher-=26
    elif letter in string.ascii_lowercase:
        code_cipher=ord(letter)+key[i]
        if code_cipher>122:
            code_cipher-=26
    else:
        code_cipher=ord(letter)
    letter_cipher=chr(code_cipher)
    text_cipher+=letter_cipher
    
print("text_cipher=", text_cipher)
 
for i,letter in enumerate(text_cipher):
    
    if letter in string.ascii_uppercase:
        code_cipher=ord(letter)-key[i]
        if code_cipher<65:
            code_cipher+=26
    elif letter in string.ascii_lowercase:
        code_cipher=ord(letter)-key[i]
        if code_cipher<97:
            code_cipher+=26
    else:
        code_cipher=ord(letter)
    letter_cipher=chr(code_cipher)
    text_cipher+=letter_cipher
 
text_decipher=text_cipher
    
print("text_decipher=", text_decipher)

# -*- coding: utf-8 -*-
 
import string
 
a = input("Enter the message -> ")
text_plain = a
 
key = input("Enter the key -> ")
key = [int(v)for v in key]
print(key)
 
rep = len(text_plain)//len(key)
residue = len(text_plain) % len(key)
print("len_text_plain =", len(text_plain), "rep =", rep, "residue =", residue)
key = key * rep + key[:residue]
print("key =", key, "len_key =", len(key))
 
text_cipher = ""
for i, letter in enumerate(text_plain):
 
    if letter in string.ascii_uppercase:
        code_cipher = ord(letter)+key[i]
        if code_cipher > 90:
            code_cipher -= 26
    elif letter in string.ascii_lowercase:
        code_cipher = ord(letter)+key[i]
        if code_cipher > 122:
            code_cipher -= 26
    else:
        code_cipher = ord(letter)
    letter_cipher = chr(code_cipher)
    text_cipher += letter_cipher
 
print("text_cipher =", text_cipher)
 
text_decipher = ""
for i, letter in enumerate(text_cipher):
 
    if letter in string.ascii_uppercase:
        code_cipher = ord(letter)-key[i]
        if code_cipher < 65:
            code_cipher += 26
    elif letter in string.ascii_lowercase:
        code_cipher = ord(letter)-key[i]
        if code_cipher < 97:
            code_cipher += 26
    else:
        code_cipher = ord(letter)
    letter_cipher = chr(code_cipher)
    text_decipher += letter_cipher
 
print("text_decipher =", text_decipher)