TypeError: can't concat str to bytes when converting Python 2 to 3 with Encryption Function

Question

I am trying to transfer a code from python2 to 3. The problem happens. "pad * chr(pad)" looks like a string but when I print it out it shows . I dont know what it is really is.

<ipython-input-26-6c9679723473> in aesEncrypt(text, secKey)
     43 def aesEncrypt(text, secKey):
     44     pad = 16 - len(text) % 16
---> 45     text =text +  pad * chr(pad)
     46     encryptor = AES.new(secKey, 2, '0102030405060708')
     47     ciphertext = encryptor.encrypt(text)

TypeError: can't concat str to bytes

I then tried encode() but it didnt work. I am wonder how can concat two string in python3.

<ipython-input-53-e9f33b00348a> in aesEncrypt(text, secKey)
     43 def aesEncrypt(text, secKey):
     44     pad = 16 - len(text) % 16
---> 45     text = text.encode("utf-8") + (pad * chr(pad)).encode("utf-8")
     46     encryptor = AES.new(secKey, 2, '0102030405060708')
     47     ciphertext = encryptor.encrypt(text)

AttributeError:'bytes' object has no attribute 'encode'

For the reference the original code is

作者：路人甲
链接：https://www.zhihu.com/question/31677442/answer/119959112
#encoding=utf8
import requests
from bs4 import BeautifulSoup
import re,time
import os,json
import base64 
from Crypto.Cipher import AES
from pprint import pprint 

Default_Header = {
                  'Referer':'http://music.163.com/',
                  'Host':'music.163.com',
                  'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Iceweasel/38.3.0',
                  'Accept':'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
                  'Accept-Encoding':'gzip, deflate'
                }

BASE_URL = 'http://music.163.com'

_session = requests.session()
_session.headers.update(Default_Header)

def getPage(pageIndex):
    pageUrl = 'http://music.163.com/discover/playlist/?order=hot&cat=全部&limit=35&offset='+pageIndex
    soup = BeautifulSoup(_session.get(pageUrl).content)
    songList = soup.findAll('a',attrs = {'class':'tit f-thide s-fc0'})
    for i in songList:
        print i['href']
        getPlayList(i['href'])

def getPlayList(playListId):
    playListUrl = BASE_URL + playListId
    soup = BeautifulSoup(_session.get(playListUrl).content)
    songList = soup.find('ul',attrs = {'class':'f-hide'})
    for i in songList.findAll('li'):
        startIndex = (i.find('a'))['href']
        songId = startIndex.split('=')[1]
        readEver(songId)

def getSongInfo(songId):
    pass

def aesEncrypt(text, secKey): 
    pad = 16 - len(text) % 16 
    text = text + pad * chr(pad) 
    encryptor = AES.new(secKey, 2, '0102030405060708') 
    ciphertext = encryptor.encrypt(text) 
    ciphertext = base64.b64encode(ciphertext) 
    return ciphertext 
def rsaEncrypt(text, pubKey, modulus): 
    text = text[::-1] 
    rs = int(text.encode('hex'), 16)**int(pubKey, 16) % int(modulus, 16) 
    return format(rs, 'x').zfill(256) 
def createSecretKey(size): 
    return (''.join(map(lambda xx: (hex(ord(xx))[2:]), os.urandom(size))))[0:16] 

def readEver(songId):
    url = 'http://music.163.com/weapi/v1/resource/comments/R_SO_4_'+str(songId)+'/?csrf_token=' 
    headers = { 'Cookie': 'appver=1.5.0.75771;', 'Referer': 'http://music.163.com/' } 
    text = { 'username': '', 'password': '', 'rememberLogin': 'true' } 
    modulus = '00e0b509f6259df8642dbc35662901477df22677ec152b5ff68ace615bb7b725152b3ab17a876aea8a5aa76d2e417629ec4ee341f56135fccf695280104e0312ecbda92557c93870114af6c9d05c4f7f0c3685b7a46bee255932575cce10b424d813cfe4875d3e82047b97ddef52741d546b8e289dc6935b3ece0462db0a22b8e7' 
    nonce = '0CoJUm6Qyw8W8jud' 
    pubKey = '010001' 
    text = json.dumps(text) 
    secKey = createSecretKey(16) 
    encText = aesEncrypt(aesEncrypt(text, nonce), secKey) 
    encSecKey = rsaEncrypt(secKey, pubKey, modulus) 
    data = { 'params': encText, 'encSecKey': encSecKey } 
    req = requests.post(url, headers=headers, data=data) 
    total = req.json()['total']
    if int(total) > 10000:
        print songId,total
    else:
        pass


if __name__=='__main__':
    for i in range(1,43):
        getPage(str(i*35))

Answer 1

around line 85: encText = aesEncrypt(aesEncrypt(text, nonce), secKey)

aesEncrypt() is called first time with data as shown with subscript '_1' and 2nd time with data shown with subscript '_2'. Notice that the type of secKey changes from a string to a list of strings, and text from a string to a bytes object.

>>> secKey_1
'0CoJUm6Qyw8W8jud'
>>> secKey_2
['e4', '1a', '61', '7c', '1e', '62', '76', '5', '94', '62', '5a', '92', '9', 'fd', '2f', '4a']
>>> 
>>> text_1
'{"username": "", "password": "", "rememberLogin": "true"}'
>>> text_2
b'qjTTWCVgh3v45StLOhGtNtY3zzoImIeGkRry1Vq0LzNSgr9hDHkkh19ujd+iqbvXnzjmHDhOIA5H0z/Wf3uU5Q=='
>>> 

Answer 2

Thanks to @Todd. He has found the issue. aesEncrypt()has been called twice and it returns bytes while it receives str, which is acceptable in Python2 but not for Python3.

In the end, I change return ciphertext to return str(ciphertext).