Question

Using Ubuntu SeedLab

To understand the error propagation property of various encryption modes, we would like to do the following exercise:
1. Create a text file that is at least 1000 bytes long.
2. Encrypt the file using the AES-128 cipher.
3. Unfortunately, a single bit of the 55th byte in the encrypted file got corrupted. You can achieve this corruption using the bless hex editor.
4. Decrypt the corrupted ciphertext file using the correct key and IV.

Please answer the following question: How much information can you recover by decrypting the corrupted file, if the encryption mode is ECB, CBC, CFB, or OFB, respectively? Please answer this question before you conduct this task, and then find out whether your answer is correct or wrong after you finish this task. Please provide justification.

Answer 1

Encrypt
**********
openssl enc -v -aes-128-ecb -K 6162636465666768696a6b6c6d6e6f70 -nosalt -in file.txt -out enc.txt

Decrypt
**********
openssl enc -d -v -aes-128-ecb -K 6162636465666768696a6b6c6d6e6f70 -nosalt -in currpted.txt -out repair.txt

you can check the corrupted info in the below comparison

thanks !