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Truecrypt defeats FBI

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Eóin:
Here's an interesting article I've read over at The Register about a Brazilian banker.

Putting particular case aside, I don't actually take much joy in seeing a crooked financial businessman getting away with crime. What interests me is how much this speaks for the credibility of Truecrypt. For starters it pretty much cements the fact that there is no backdoor in the program. Now admittedly being opensource such a door would be hard to find but nonetheless this is most reassuring.

It's also a testament to the quality and robustness of the cryptography within Truecrypt as often when security like this is compromised it's down to bad implementation and not weaknesses in the algorithms

Josh:
The thing with this article is that Truecrypt "And an unnamed security product" defeated the FBI. Plus, I guarantee there is more to this story.

Eóin:
Well it says an 'unnamed algorithm' rather than another program. Truecrypt offers a number alternative encryption algorithms as well as cascaded combinations.


Obviously one can't be sure but I'd sooner guess that it was simply one of those, after all rolling your own crypto algorithm is never a good idea.

Deozaan:
It's also a good thing (for the banker) that he used a strong password. TrueCrypt alone won't help if your password sucks.

40hz:
Hmm...

One old technique is to intentionally corrupt the encrypted file in a reversible manner. All you need to do is open the encrypted file in a hex editor, change one or more bytes using some arbitrary schema, and save it.

Example: After encrypting, add 1 to the first byte in the first three rows.

Original file



After encryption


After editing hex values


Until these changes are reversed, the file cannot be decrypted even if the password and encryption method are known. Since encryption algorithms depend on every byte in the encrypted file being correct, any change anywhere in the file makes decryption impossible. And because the changes made are completely arbitrary, they don't readily yield to cryptographic analysis and cracking techniques.

Note that many encryption software products also add headers and CRC checksums to their output files, so it's important to test the "corrupted" file to make sure the encryption utility can't repair it. The goal is to have decryption produce gibberish or no output rather than report a file error - which is a dead giveaway that the encrypted file had been tampered with.

Encrypting the same file twice, using two different algorithms and passwords (or even using the same algorithm and password) can also make cracking the file virtually impossible.

And any encryption system that utilizes a properly implemented One-Time Pad technique is still completely unbreakable using analytic methods.

At least according to all the information that is publicly available.  8)  ;D

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