Re: Newbie naive question, perhaps - - be kind

On Sat, 15 Oct 2005 15:47:06 +0000, Arthur wrote:

> 1) Some of the commercial programs, such as Cryptainer,

I personally have never heard of this product. However, a brief skim of
their site doesn't ring any alarm bells.

seem to suggest
> that their encryptions are essentially unbreakable: trillions of years
> of computer time would be required to break their Blowfish and AES
> encryption schemes in the program. Yet they suggest long passwords or
> pass phrases to make hacking these passwords "more difficult." They
> encouraged written questions from potential buyers, but have not
> answered my question: isn't the program as weak as its weakest link,
> e.g. the password??

Yes, it is. Hopefully newbie-friendly explanation:

If:

1, your encryption program uses AES (or Blowfish as far as I know);

2. it implements it properly;

3. it doesn't include any kind of "back door" or "emergency key recovery"
or (various other euphemisms which boil down to it stashing the key
somewhere obscure and hoping nobody finds it; they will, they will);

4. does various other technical details correctly;

then the only practical way, as far as anybody[1] knows, to recover your
data, is to guess what your password was. If the password is short, or is
a real word, then they can use a computer (or, more to the point, lots of
computers) to do the guessing. This is called a "dictionary attack". If
your password is long and at least somewhat gibberish, then this is much
more difficult. Long and random enough, and the effort required will be
more than anybody can be bothered to expend. At this, point, you have won.

[1] That is, anybody in the open cryptography community. What else the NSA
and friends may or may not know is an open question, since they don't tell
anyone. The smart money is that they can't do anything with it either; no
doubt the chaps in tinfoil hats would take a different view.

> 2) if these encryption schemes are so unbreakable, and commercially
> available, why haven't I heard news items describing "terrorists" and
> their use of unbreakable encrypted e-mail ("tomorrow at 10:15, Sidney,
> we light the fuse")?

http://en.wikipedia.org/wiki/Traffic_analysis

You might also care to consider the various political relationships which
exist in the realms of journalism and media broadcasting. There's a lot
more that goes on in the world, than gets onto the news. (And remember,
it's *shiny* side out.)

Can I assume that "hackability" or unbreakability
> is merely a matter of degree, and that the police or local computer
> repairman will in all likelihood be intrigued in my newly encrypted data
> files and e-mail and therefore try all the harder to see what's within?

OK, you're mixing up several different things here. "Hacking" (or
"cracking", to use the correct term, which the mainstream press never do)
is about finding flaws of one kind or another in implementations of
computer programs, and exploiting them to gain unauthorised access to a
computer and / or the data held on it. This is illegal in most "first
world" countries, and lots of other places which want the US and / or the
EU to be friends with them.

Finding flaws in encryption algorithms themselves, rather than in the
implementations (the "recipe", if you like, rather than the actual cake
that somebody baked from it) is called "cryptanalysis". It's a branch of
mathematics, and is carried on by people who are a lot smarter than me.
It's legal.

That said, you are correct in that "unbreakable" is a pretty woolly term.
There are four main subdivisions:

1. One-time-pad. This really *is* unbreakable. You can prove it
mathematically. However, nobody uses these because they have plenty of
other problems. Any program which claims to use "one-time-pads", a)
doesn't, b) is snake oil, and c) should be avoided like the plague.

2. Computationally infeasible. If you have planet-sized computers, and
live for thousands of years, you can break this in what, to you, is a
reasonable length of time. If you're an early 21st century human, you
don't, so you can't. AES with a 128-bit, *properly random* key, falls into
this category, as far as we know.

3. Good enough. Takes longer, and / or needs more computers, than anybody
who is interested in you can be bothered to devote to the matter.

4. Term of art in websites promoting snake oil. Usually translates as
"massively flawed and capable of being broken in about half an hour if
somebody competent put their mind to it."

Successful cryptanalysis of AES or even Blowfish is not something you need
to worry about. If your application is using some other algorithm,
especially if they won't tell you what it is, then it's probably snake
oil, and you do. The snake-oil FAQ can be found at
http://www.faqs.org/faqs/cryptography-faq/snake-oil/ and is recommended
reading.

If some random computer technician sees a bunch of encrypted stuff, he may
well be intrigued. (He will probably guess it to be porn :-) However, if
you've chosen a good passphrase, and everything else I wrote at the
beginning holds true, then his curiosity will get him nowhere.

If law enforcement see it, they may also be intrigued. It won't get them
anywhere either. Their next step may be to come and have a chat with you.
If this happens, you should probably call your boss, and have him/her call
your legal department. However, none of this is too likely, so I wouldn't
worry about it.

HTH

Will.
Received on Mon Oct 17 20:48:20 2005