I received an interesting challenge today from my teacher(the problem can be solved). The only thing i have is a 1MB AES-encrypted file and i have to decrypt it and find some information within. I assume the mode used was ECB-128, because from what i read it is the only aes mode that can be cracked due to the repeated use of the same key, but i'm not sure if i'm on the right path. What is the best way to approach such a challenge?
EDIT: One of the hints we got is that the password contains "2014" either at the beginning or at the end of the key(not sure if it helps very much, the key space is still very big). But because the file is so large, i'm really thinking it could be an image, so i'll try reconstructing the header and reading the image, maybe i'll discover something.
In ECB mode, identical blocks of plaintext are encrypted to identical blocks of ciphertext. So typically you're looking for patterns of identical blocks of ciphertext (aligned to 16-byte boundaries). The ECB Penguin is probably the most famous demonstration of the problem and should point you in the right direction for exploring the data you have.