This is a continuation of this question. Please do not mark this question as a duplicate for it has a different error I need to fix.
TL;DR for the link:
So I was asking about a Unicode error in python for my encryption program and someone told me to just encode the password in utf-8 and it worked.
Now I have a second problem, where it says that the IV isn't 16 bytes, so I checked this by putting print(len(IV)) after the IV and after running 3 tests it only returns 16 once, in the middle of the printed characters, and the end character is greater than 16 (eg: 37, 35, 28, etc.).
How could I fix this so that the IV always returns 16 bytes?
Full error:
Traceback (most recent call last):
File "/home/pi/Desktop/Projects/FyleCript/Dev Files/encryption.py", line 77, in <module>
encrypt(SHA256.new(password.encode('utf-8')).digest(), str(Tfiles))
File "/home/pi/Desktop/Projects/FyleCript/Dev Files/encryption.py", line 17, in encrypt
encryptor = AES.new(key, AES.MODE_CBC, IV)
File "/usr/lib/python3/dist-packages/Crypto/Cipher/AES.py", line 94, in new
return AESCipher(key, *args, **kwargs)
File "/usr/lib/python3/dist-packages/Crypto/Cipher/AES.py", line 59, in __init__
blockalgo.BlockAlgo.__init__(self, _AES, key, *args, **kwargs)
File "/usr/lib/python3/dist-packages/Crypto/Cipher/blockalgo.py", line 141, in __init__
self._cipher = factory.new(key, *args, **kwargs)
ValueError: IV must be 16 bytes long
Code:
def encrypt(key, filename):
chunksize = 64 * 1024
outFile = os.path.join(os.path.dirname(filename), "(encrypted)"+os.path.basename(filename))
filesize = str(os.path.getsize(filename)).zfill(16)
IV = ''
for i in range(16):
IV += chr(random.randint(0, 0xFF))
encryptor = AES.new(key, AES.MODE_CBC, IV)
with open(filename, "rb") as infile:
with open(outFile, "wb") as outfile:
outfile.write(filesize)
outfile.write(IV)
while True:
chunk = infile.read(chunksize)
if len(chunk) == 0:
break
elif len(chunk) % 16 !=0:
chunk += ' ' * (16 - (len(chunk) % 16))
outfile.write(encryptor.encrypt(chunk))
def decrypt(key, filename):
outFile = os.path.join(os.path.dirname(filename), os.path.basename(filename[11:]))
chunksize = 64 * 1024
with open(filename, "rb") as infile:
filesize = infile.read(16)
IV = infile.read(16)
decryptor = AES.new(key, AES.MODE_CBC, IV)
with open(outFile, "wb") as outfile:
while True:
chunk = infile.read(chunksize)
if len(chunk) == 0:
break
outfile.write(decryptor.decrypt(chunk))
outfile.truncate(int(filesize))
Any help would be appreciated.
Well, let's take a look at what IV may consist of:
IV = ''
for i in range(16):
IV += chr(random.randint(0, 0xFF))
Let's see how many bytes a character from range(0, 0xff) consumes:
>>> [len(chr(i).encode()) for i in range(0, 0xff)]
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]
And this is the source of the problem: you're assuming each character is one byte long, but that's not the case.
You can generate a random IV of N bytes with the following code:
import os
N = 16
IV = os.urandom(N)
Another issue in your code is that you're opening all your files in 'rb' mode, which stands for "read binary", but attempting to write to it instances of str, like your IV. That won't work because in this mode you're only allowed to read and write bytes, not str. In my solution for calculating the IV this issue completely disappears.