encryption key for EFS

[meeee]

I had a couple of files encrypted on my hard disk. But when i did a fresh install of windows i forgot to backup the encryption keys for the files. Im a computer science student so i know decrypting these files without the key is basically impossible.

What I do want to ask though, is it possible to find out the encryption key if you have BOTH an encrypted version and unencrypted version of a file? Surely, if you know the encryption algorithm there should be enough information there to find the key?

 

[cell4me]

Discussing cracks, hacks or anyother way to break into a computer is against forum rules...please read the sticky!

 

[jancz3rt]

Hmm

I do not think this is against forum rules. He has a good point...or rather a good idea. I know of no way of doing it, but there is some logical assumption behind it.

JAN

 

[cell4me]

So basically teaching someone how to break into encrypted files is okay?

 

[jancz3rt]

Hey

As you have noticed, nobody seems to know. I do agree that it is questionable but he says he has the original and the encrypted. Most people who would want to know how to break encryption do not have that luxury He wants to know the key and probably knows that all other files are encrypted with the same key.

P.S.: No more posts from me.

JAN

 

[cell4me]

The answer to your question is no, even though you have the encryption algorithm there is still going to be too many possibilities!

 

[meeee]

Discussing cracks, hacks or anyother way to break into a computer is against forum rules...please read the sticky!

lol these are MY files! Cos microsoft sucks they dont really tell you how their own encryption thing works in xp. So when you do a fresh install and want to access your files that you encrypted previously you cant. You then do some research and find out the encryption key was deleted with the format (yes I already tried recoverin the deleted files but I couldn't find it)

There is NOTHING illegal about cracking an encryption unless you are packet sniffing.

 

[meeee]

The answer to your question is no, even though you have the encryption algorithm there is still going to be too many possibilities!

All good encryption algorithms are made public. Its the best way. Its like sayin "this way is so good nobody knows how to crack it"

I understand it is virtually impossible to crack an encryption with sufficient bits in the key. But surely, having both an encrypted and unencrypted version of the file plus the encryption algorithm whittles dowm the possibilities drastically enough to have a computationally feasible "brute force" way to generate the key?

If there is ever a workable quantum computer invented then all current encryption methods would be renedered obselete.

 

[cell4me]

All the programs I know of generate the key randomly, so in theory it would not whittle down the possibilities.

 

[meeee]

All the programs I know of generate the key randomly, so in theory it would not whittle down the possibilities.

For windows encryption, the key is generated randomly the first time it is required. From then on that same key is used for the encryptions.

 

[dragon2309]

I think you need to go and find a specialised security forum, this is just a meer computerforum.

 

[meeee]

I think you need to go and find a specialised security forum, this is just a meer computerforum.

hehe my problem aint that important. Only a very small proportion of my files were encrypted, I just used it to try it out.

Cos I love my technology, im just tryin out of academic interest.

 

[SFR]

Sorry everyone... interesting subject but rules are rules...

Forum Rules
1. Posting/discussion about software cracks, serial no's, and illegal downloading and duplication of software is prohibited.
2. Discussions which actively encourage illegal hacking/malicious harm to computers/networks is prohibited.