AES 256 is virtually impenetrable using brute-force methods. While a 56-bit DES key can be cracked in less than a day, AES would take billions of years to break using current computing technology. Hackers would be foolish to even attempt this type of attack. Nevertheless, no encryption system is entirely secure.

Has AES 256 ever been cracked?

AES, which typically uses keys that are either 128 or 256 bits long, has never been broken, while DES can now be broken in a matter of hours, Moorcones says. AES is approved for sensitive U.S. government information that is not classified, he adds.

Is AES 256 still safe?

AES-256 is definitely secure for file storage. The only weakness is the key that you choose. As long as you choose a strong key for it, AES-256 will keep your files safe. According to this Wikipedia page, the best attack on AES was published in 2011 and to break AES-256, it still required 2^254.4 operations.