128bit encryption

[Birt]

If something has 128bit encryption how secure is it?

I am thinking about using Adobe Acrobat for legal reports but not sure how secure they are once password protected. I will be using 12 character passwords that are a mix of numbers/letters (uppercase and lower case) /characters

[rojash]

This from wikipedia:

"The amount of time required to break a 128 bit key is also daunting. Each of the 2128 possibilities must be checked. This is an enormous number, 340,282,366,920,938,463,463,374,607,431,768,211,456 in decimal. If a device could be built that could check a billion billion keys (1018) per second, 10,790,283,070,806 years would still be required to exhaust the key space. By way of comparison, current evidence indicates that the age of the universe is only about 13,000,000,000 years."

However, it would take considerably less time to crack a 12 character password.

[fo3nix]

128-bit means nothing.

1) it depends on what algorithm is being used. AES-128, for example.
2) it's closed source. even if the mathematical algorithm is totally unbreakable (though nothing is), if the implementation of it is flawed then the entire thing crumbles down. since you or an expert can't check to see how good the implementation is, it should not be trusted as being secure at all (if you value your security at all).

If security is important to you, I'd advise that you get GPG (it's free; windows version here: http://www.gpg4win.org/). This lets you encrypt any sort of file that you like at all, and it's very secure indeed. It's also the secure way of emailing other people the documents, if you ever need to do that.

Alternately, you could get truecrypt (also free: http://www.truecrypt.org/), which creates a virtual 'disk' on your computer that is encrypted. This means you just have to enter the password once and then it appears just like a normal drive on your computer, S: for instance. You can save whatever you want to it then, and then it'll be locked in there. Without the password there's no change you can get hold of the data.

[ACtheTROLL]

Neither answer is wrong ... or complete (this isn't either!)
but .... look round at your options .... adobe's own "protection" is reasonable ... but not supported by any government. http://www.cs.cmu.edu/~dst/Adobe/Gallery/anon2 1jul01-pdf-encryption.txt .....

Dedicated progs such as Truecrypt, PGP etc are front ends to accepted methods and algorythms and thus strength of encryption they offer (aes, cast5, blowfish two fish etc etc) ....
(the difference tends to be in the front end - file, container or partition encryption .... so given that you chose one of the mainstream packages using mainstream standards your question is a fair one.

aes encryption is cleared by the pentagon for information classified as "secret" - 256 is up to "top secret"
but It's not uncrackable .... the question is - how important is the info? and .... are you worth the effort (and time) required to crack it?

I'd say PDF is a useful cross platform method of sharing information Use it for what it is - a password will hinder bur Elcom sell a PDF unlocker which works quick and well

when you consider encryption ... is it for your storage needs .... or selective sharing?
and is hinderance enough or do you need something stronger?

and remember in all cases the longer the password ... the harder it is for a casual thief to crack.