Sending Encrypted Data Through Socket And Decrypting Doesn't Work - python-2.7

Question

I am creating a simple encryption software. The problem I currently have is that sending encrypted aes file data through a socket doesn't work. At the receiving end, the file that should be written to is empty. I have looked through my code for a good while and can't see to solve it.
I have made a version without networking.
I have been able to send a small file up to 8 KB on a different version
My Program Is Function Based So The Program Branches Off From The Main Menu To Other Menues And Functions. Since There is A Bit Of Jumping, It Would Be Best To Show All The Code.
https://github.com/BaconBombz/Dencryptor/blob/Version-2.0/Dencryptor.py
The socket connects, and all required data is sent. Then, the file is AES encrypted and sent through the socket. The Receiving end writes encrypted data to a file and decrypts it. The program will say the file was sent but on the recieving end, the program spits out a struct error because the file that should have the encrypted data is empty.

Answer 1

The code is too non-minimal so here's a minimal example of downloading an unencrypted file. Also, TCP is a streaming protocol and using sleeps to separate your data is incorrect. Define a protocol for the byte stream instead. This is the protocol of my example:
Open the connection.
Send the UTF-8-encoded filename followed by a newline.
Send the encoded file size in decimal followed by a newline.
Send the file bytes.
Close the connection.
Note this is Python 3 code since Python 2 is obsolete and support has ended.
server.py
from socket import *
import os
CHUNKSIZE = 1_000_000
# Make a directory for the received files.
os.makedirs('Downloads',exist_ok=True)
sock = socket()
sock.bind(('',5000))
sock.listen(1)
with sock:
while True:
client,addr = sock.accept()
# Use a socket.makefile() object to treat the socket as a file.
# Then, readline() can be used to read the newline-terminated metadata.
with client, client.makefile('rb') as clientfile:
filename = clientfile.readline().strip().decode()
length = int(clientfile.readline())
print(f'Downloading {filename}:{length}...')
path = os.path.join('Downloads',filename)
# Read the data in chunks so it can handle large files.
with open(path,'wb') as f:
while length:
chunk = min(length,CHUNKSIZE)
data = clientfile.read(chunk)
if not data: break # socket closed
f.write(data)
length -= len(data)
if length != 0:
print('Invalid download.')
else:
print('Done.')
client.py
from socket import *
import os
CHUNKSIZE = 1_000_000
filename = input('File to upload: ')
sock = socket()
sock.connect(('localhost',5000))
with sock,open(filename,'rb') as f:
sock.sendall(filename.encode() + b'\n')
sock.sendall(f'{os.path.getsize(filename)}'.encode() + b'\n')
# Send the file in chunks so large files can be handled.
while True:
data = f.read(CHUNKSIZE)
if not data: break
sock.sendall(data)