🔒 Decryption not working

[wary wolf]

I made these two encryption & decryption functions:

    def encrypt(self, data, password, password2):
        salt = get_salt()
        key = scrypt(password, salt, 32, N=2 ** 14, r=8, p=1)
        cipher = AES.new(key, AES.MODE_CBC)
        ct_bytes = cipher.encrypt(pad(data.encode(), AES.block_size))

        salt2 = get_salt()
        key2 = scrypt(password2, salt2, 32, N=2 ** 14, r=8, p=1)
        cipher2 = AES.new(key2, AES.MODE_CBC)
        ct2_bytes = cipher2.encrypt(pad(ct_bytes, AES.block_size))

        iv = base64.b64encode(cipher.iv).decode()
        ct = base64.b64encode(ct2_bytes).decode()
        salt = base64.b64encode(salt.encode()).decode()
        salt2 = base64.b64encode(salt2.encode()).decode()

        return f"{iv}:{ct}:{salt}:{salt2}"

    def decrypt(self, data, password, password2):
        iv, ct, salt, salt2 = data.split(":")
        iv = base64.b64decode(iv)
        ct = base64.b64decode(ct)
        salt = base64.b64decode(salt).decode()
        salt2 = base64.b64decode(salt2).decode()

        key2 = scrypt(password2, salt2, 32, N=2 ** 14, r=8, p=1)
        cipher2 = AES.new(key2, AES.MODE_CBC)
        pt2 = unpad(cipher2.decrypt(ct), AES.block_size).decode()

        key = scrypt(password, salt, 32, N=2 ** 14, r=8, p=1)
        cipher = AES.new(key, AES.MODE_CBC, iv=iv)
        pt = unpad(cipher.decrypt(pt2.encode()), AES.block_size).decode()

        return pt

Encryption is working fine for me, it's decryption that's the issue. Getting this error from line pt2 = unpad(cipher2.decrypt(ct), AES.block_size).decode()

UnicodeDecodeError: 'utf-8' codec can't decode byte 0x8b in position 9: invalid start byte

I don't really understand encoding and decoding (conversion from chars to bytes??) so I appreciate any help with this.

[formal pike]

@wary wolf

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[wary wolf]

I'm not sure if it's neccessary to send my other functions, as I suspect these are the root of the problem but let me know if I should

[sonic creek]

mid process python uses unicode so idk but it could be that they are unicode bytes trying to be decoded to utf-8 by any chance idk

[wary wolf]

So should I specify and different encoding to .decode()?

I thought utf-8 is based off unicode?

[sonic creek]

idk i dont do this kind of stuff either its just a guess

[narrow grail]

Why are you trying to decode there? It's bytes and it should be bytes at this point, shouldn't it? The decode tries to make it into a string

[wary wolf]

You're right, and then I go and encode it again for no reason

Let me try it

[narrow grail]

In the encrypt you don't have .encode() for that part, so you don't need decode

[wary wolf]

Now I can get past that line, but still having another issue

[narrow grail]

Treat the functions as opposites and reverse each action from the end - if needed, check the types.
You could also print stuff at each step in encoding and then in decoding - and compare

[wary wolf]

I'll try that and come back if I can't figure it out

[hidden quiver]

Encryption is working fine for me, it's decryption that's the issue.

I'm probably not helping here, but you don't know if the encryption is working if the decryption isn't working 🤣

[wary wolf]

Yeah I guess so... haha

But getting no errors at least

I found an inconsistency but I'm not sure what it means:

During the first encryption it gives out b'\xf8\xe9\xabfL\x99VEa\xd0!\xb0g\xc6\x1bk',
and on the first decryption I get b"n\xb4h\x9d4\xce\xb17?\xf3\xd1\xfa\xc5\x7f'\x8f"

I think it's an issue with salt encoding/decoding

Perhaps when i put the salt in the f string

is it converting bytes to a string somehow?

[formal pike]

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