Hi everyone, I’m working on a school project due the day after tomorrow, and I really need help with implementing AES-128 encryption and decryption for files in Python without using the aes library so I’m implementing all AES functions from scratch—such as SubBytes, MixColumns, ShiftRows, and AddRoundKey.

So far, I’ve managed to get the encryption part working (or at least I think it’s correct), but I’m completely stuck on decryption. I’m not sure if the issue is because of something in the encryption step or if there’s a problem in how I’m handling the decryption.I’ve tried several approaches for decryption, but the output remains encrypted—I’m not getting the original file back.

Here’s what’s happening:

• I feel completely lost, and I’m running out of time—any guidance on implementing AES-128 decryption without a library would be a huge help.
• I’ve tried various codes for decryption, but I don’t end up with the decrypted file; it’s still unreadable or looks like encrypted data

Any tips, resources, or even an outline of the decryption process would mean a lot. Thanks in advance for your help!