How long would it take with current hardware to hack an Disk Image which was enc

Question

How long would it take with current hardware to hack an Disk Image which was encrypted with AES 256?

I ask because i want to backup personal files (contracts, tax-things, code, keys, private documents) and leave them outside of my home (e.g. at the office, at dropbox or AWS).

Is it a good/safe idea or not? Since i am not the president of the united states, i think others are not that interested in my files as i was the president ;) But i want to have still a good sleep while the files are stored as the destinations mentioned above.

Explanation / Answer

How fast can you crack AES-256?

Either never (within next two centuries) or within days.

AES-256 is considered incrackable by itself. Even most implementations are considered safe. (no side-channels).

OTR protocol uses AES-128 (weaker than AES-256) as symmetric encryption algorithm and the world's best funded intelligence agency NSA wasn't able to decrypt it.

However it comes down to the question of the context of AES-256.
If you use weak keys (which are easy to guess), it's crackable quite soon. Most implementations use very strong keys, which are as safe as AES.
If you use a weak mode (->ECB) one can recognize patterns and hence "break" AES by breaking the context within it's used. Most implementations use safe modes (CBC/CTR/GCM/CCM/EAX/...)
If your implementation (your overall program) is flawed, it might be possible to extract keys or get the plain text anyhow else. This isn't impossible, but very unlikely if you use the right programs (like TrueCrypt).
If your key-derivation is weak, one could crack that and hence get the keys. This is very unlikely and most implementations use counter-measures.
If your key input is too weak, one could break the system. "weak key input" here means weak passwords, weak keyfiles, weak authentication mechanisms. Most implementations do their very best to protect you even if you choose a somewhat weak password. This should be your greatest concern.

Of course this isn't everything, there are also issues if you consider altered data as a threat.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.