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First Phase of TrueCrypt Audit Turns Up No Backdoors
msm1267 (2804139) writes "A initial audit of the popular open source encryption software TrueCrypt turned up fewer than a dozen vulnerabilities, none of which so far point toward a backdoor surreptitiously inserted into the codebase. A report on the first phase of the audit was released today (PDF) by iSEC Partners, which was contracted by the Open Crypto Audit Project (OCAP), a grassroots effort that not only conducted a successful fundraising effort to initiate the audit, but raised important questions about the integrity of the software.
The first phase of the audit focused on the TrueCrypt bootloader and Windows kernel driver; architecture and code reviews were performed, as well as penetration tests including fuzzing interfaces, said Kenneth White, senior security engineer at Social & Scientific Systems. The second phase of the audit will look at whether the various encryption cipher suites, random number generators and critical key algorithms have been implemented correctly."
The first phase of the audit focused on the TrueCrypt bootloader and Windows kernel driver; architecture and code reviews were performed, as well as penetration tests including fuzzing interfaces, said Kenneth White, senior security engineer at Social & Scientific Systems. The second phase of the audit will look at whether the various encryption cipher suites, random number generators and critical key algorithms have been implemented correctly."
Wow, a code audit. What a great idea for a FOSS project.
much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
just important this audit is...
This is why open source is so important.
The first phase of the audit focused on the TrueCrypt bootloader and Windows kernel driver. Not really surprising that they didn't find any critical security issues in those parts. The high value bugs should be in the crypto parts and how they are implemented.
The code is being audited in America. That's pretty funny.
How about an audit in a country where the NSA cannot tell the auditors to shutup?
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Since Snowden's revelation about the NSA's clandestine $10 million contract with RSA,
If you're on NSA's radar you've got bigger problems than TrueCrypt's trustworthiness or lack thereof. The NSA doesn't have to have a back door into AES (or the other algorithms) when they have an arsenal of zero day exploits, side channel attacks, social engineering, and TEMPEST techniques at their disposal. The average user should be far more concerned about these attack vectors (from any source, not just NSA) than the security of the underlying encryption algorithm.
The Diceware FAQ sums up the problem rather succinctly: "Of course, if you are worried about an organization that can break a seven word passphrase in order to read your e-mail, there are a number of other issues you should be concerned with -- such as how well you pay the team of armed guards that are protecting your computer 24 hours a day."
I want peace on earth and goodwill toward man.
We are the United States Government! We don't do that sort of thing.
Tell me this: if the NSA did put a backdoor in the package and if this audit found it, how would the NSA know about it in time to prevent it being reported? Sending a security letter to the auditors would just be considered proof that there was a backdoor to be hidden. The auditors may have been forced not to reveal anything about it to the general public, but you can bet that the people over at TrueCrypt would have found out about it and eliminated it as soon as possible, although they'd probably have had to pretend that they found the flaw themselves to protect both themselves and the auditors.
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Technically, if an NSA backdoor existed in the codebase, you would be prevented from reporting it by an NSA letter, subject to immeadiate imprisonment and confiscation.
Two responses.
First, I suspect if they were confronted with an NSL they could go the lavabit route and simply suspend the audit project with no explanation. IANAL but I don't think the NSA can compel them to falsify the audit results.
Second, if they are smart, they can have it audited multi-nationally with independent auditors to make it harder for any government gag orders to stick.
isn't it possible to just have your backdoor be inserted by the compiler ?
I've been coding in C a long time and one of the medium security faults makes no sense to me:
"Windows kernel driver uses memset() to clear sensitive data"
The reasoning they give is:
"...However, in a handful of places, memset() is used to clear potentially sensitive data. Calls to memset() run the risk of being optimized out by the compiler."
WTF?!?
I suppose a smart compiler can optimize out a memset() if it's directly preceeded by a calloc() or something, but I have never had any compiler ever just ignore my request to memset().
What am I missing here?
And Germany and France and South Korea and Japan and Brazil and China and Australia and New Zealand, etc. Or do you honestly think only those 3 countries spy on their citizens?
Oh hell, they'll just sneak into your home in the middle of the night and plant a hardware bug or key logger into your computer.
One of their favorite tactics used by law enforcement is to install cameras in your residence facing where you normally use your computer. They got a child pornographer like this, his use of true crypt didn't help because they had video of him entering the password and simply entered the password once they seized the computer.
True Crypt cannot reasonably protect you from law enforcement nor state sponsored spying like the NSA. It might protect you from some non-tech police agency in some shit hole country being able to access it but then they just use the standard non-tech password extraction method.
Obligatory XKCD. http://xkcd.com/538/
The problem with the NSA is we have no idea what their capabilities are, technologically or legally. They are clearly violating the constitution already and there seems to be no one willing or capable of stopping them. So if they did come to you with a NSL, no matter how ridiculous or unconstitutional it was, what choice would you have? You could go to the media, but how embedded in the media are they? Do they have standing NSLs with all the media organizations out there? You could go outside the country, but those newspapers are government by their own countries version of the NSA who's working in close relationship with ours. This really is a Global totalitarian secret police state. They haven't started herding people into camps or anything, but really... what's to stop them?
Do they have standing NSLs with all the media organizations out there?
I think there'd be less Snowden leak coverage if there were. :)
You could go outside the country, but those newspapers are government by their own countries version of the NSA who's working in close relationship with ours
Like China & Russia? Governements want their own security as much as their own intelligence agencies want to break it... there's too many pieces moving in opposite directions for there to be a credible global coverup of a transparent audit of open source software.
Why does it rule those countries out?
You you perform your audits in all 3 countries, the only things being missed are backdoors put in by all 3 securities agencies cooperating together.
Add in China or some other "we don't like USA" country and you get better odds.
I use TrueCrypt. Not that it likely matters given all the other back-doors on my Lenovo Wintel laptop, but I use a passphrase from Hell, and I suspect even the NSA's biggest cracker would have trouble with it.
Other than the backdoors in various places on this toxic waste dump of security, the biggest security threat to my passphrase from Hell is TrueCrypt itself. TrueCrypt by default does 100% useless password strengthening (key stretching or whatever it's called). It's strongest mode, which you have to select manually, is 2000 rounds of SHA-256. I can buy SHA256 boxes that do 1 Giga-hash/second per $10. Figure a government has a few million at least for such boxes, and go compute how strong your password needs to be, and it isn't pretty.
I use my password and TrueCrypt to protect my data. Why didn't it occur to the TrueCrypt authors to protect my password? I mean, Bcrypt at least, come on...
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The backdoor is not in the source it is in the MVC++ compiler. NSA is not stupid, putting the backdoor in the source itself would be risky, it would be much wiser to put the backdoor in the MVC++ compiler itself.
at least the sores are open, so that one may take a puss sample and analyse it for disease. When the sores are closed, who knows what you'll wake up with in the morning.
If you're on NSA's radar you've got bigger problems than TrueCrypt's trustworthiness or lack thereof.
In case you've been sleeping under a rock for the last year, the target of the NSA is everyone. Not that they put you on the same level as the Chinese military of course, but nobody's under their radar and if they can grab your data or metadata easily they will because you could be a terrorist or at least the friend of a friend of a friend of a terrorist. It's not that the average joe would stand a chance if they threw everything in their arsenal at us, but those "zero day exploits, side channel attacks, social engineering, and TEMPEST techniques" don't come free and using them highly increases the chances of exposing them. The question is more like "Does NSA grab all the TrueCrypt containers used as backup on Dropbox/GDrive/whatever and rifle through everyone's data?" than "If the NSA really wants the contents of my laptop, would this really stop them?"
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One way to detect a backdoored compiler to a fairly high certainty is diverse double-compiling, a method described by David A. Wheeler that bootstraps a compiler's source code through several other compilers. For example, GCC compiled with (GCC compiled with Visual Studio) should be bit for bit identical to GCC compiled with (GCC compiled with Clang) and to GCC compiled with (GCC compiled with Intel's compiler). But this works only if the compiler's source code is available. So to thwart allegations of a backdoor in Visual Studio, perhaps a better choice is to improve MinGW (GCC for Windows) or Clang for Windows to where it can compile a working copy of TrueCrypt.
A good strong PBKDF2 is probably sufficient, but yeah, 2k rounds is pathetic. iPhones were doing better (admittedly, their passphrases tend to be very short) several years ago, and that's on a mobile CPU. Having a limit of 2k rounds doesn't even make sense, it's not like it's harder to code it for more rounds or something. The only real limit should probably be 0xFFFFFFFF rounds (assuming 32-bit ints) because why have a limit at all?
There's no place I could be, since I've found Serenity...
Snowden basically walked out of the NSA with all their secrets; who's to say a few dozen or hundred other contractors didn't do the same thing before him? Everything the NSA knew or had access to before 2013 was most likely available in blackhat circles through clandestine leaks.
Any backdoors in TrueCrypt would be a security disaster, and the NSA has already proven itself willing and able to put backdoors in highly trusted security software. It's also proven itself incapable of keeping secrets.
Worrying about NSA-planted vulnerabilities is not the same thing as worrying about a direct attack from the NSA itself.
WTF?!?
WTF indeed.
There seems to be a major trend towards making compilers create code that is as different as possible from what the programmer wrote without being so different that the programmer actually notices. One might assume it's a secret NSA plot to defeat security measures in all software everywhere. You know, if one was incredibly paranoid, that is.
It's hard to say whether this is justified behavior. As an example, consider this code from a link an AC posted:
int ....
crypto_pk_private_sign_digest(....)
{
char digest[DIGEST_LEN];
memset(digest, 0, sizeof(digest));
return r;
}
Exploit mitigation code like this is a case of writing code which we expect to never have any effect, just in case we're wrong and it does have an effect. Then the compiler comes along and decides for itself that the code we wrote will never have any effect and removes it. It's kind of hard to blame it for noticing the uselessness of the operation when we ourselves expected the code to likely have no effect when we wrote it, but then, the whole reason we wrote it is because we thought we might be wrong. Should the compiler then assume that we might be wrong as well, and that we might access that memory using a different pointer?
Does it make sense to compile with optimization enabled when, by including things like the memset() call to clear memory we're finished using, we clearly have goals other than optimization?
The article mentions the fix being the use of a different function which won't be optimized away, but I wonder if even that is a legitimate fix. Our "digest" array is just another variable that the compiler is free to do whatever it wants with in the name of optimization. If it will make the program run faster, it's free to make two copies of it. Then our new never-optimized-away function will end up erasing only one copy of the variable.
So problem here isn't the use of memset() rather than some other function. The problem is that we're asking the compiler to create code that doesn't match what we've written. It should be no surprise then when it goes ahead and does that. Thus, I don't think it's correct to claim that the error here is the failure to use the correct function to clear the memory. I think the error is in asking the compiler to generate code that isn't identical to the source code.
The core of the problem is that C isn't a language that allows us to clearly tell the compiler exactly what we want to happen. Without bounds checking on pointer use, every pointer is effectively a pointer to all memory. Thus, when a pointer falls out of scope, it doesn't mean anything. That memory can still be accessed via any other pointer anywhere in the program. If C enforced bounds checking, such that accessing the data in "digest" via any other pointer was impossible, then the compiler could safely work under the assumption that once "digest" falls out of scope, the data it points to will never be accessed again, and thus removing the memset() call would be a safe thing to do since it truly would have no effect.
It really seems ridiculous when you think about it. Compilers assume that bounds on pointers will be respected, yet make no attempt whatsoever to enforce those bounds, essentially guaranteeing that they will not be respected since programmers are imperfect.
Consider what the compiler will do when it encounters code like this:
int a[4];
int b[4];
int c[4];
b[-1] = 0;
Despite the obvious error in the above code, GCC will compile it without error. It will then perform optimizations that assume that neither a[] nor c[] have been affected by the assignment to b[]. It seems rather ridiculous that anyone is expected to create secure software in such an environment. Either the compiler should enforce bounds checking, or it should assume that any pointer operation ca
was expecting something esoteric but turned out to be really straightforward
I think you failed to notice that the page talks about two separate bugs. In the first one, the memset() really is completely removed by optimization.
the type of error you make at 2am, taking the size of the pointer instead of the actual size of the buffer
I'd argue that's an error one might make any time of the day. The sizeof() operator is ambiguous. Consider the following example:
#include <stdio.h>
void main() {
char a[100];
char *b = a;
printf("address of a is %p\n", a);
printf("address of b is %p\n", b);
printf("size of a is %lu\n", sizeof(a));
printf("size of b is %lu\n", sizeof(b));
};
One might assume that, since both "a" and "b" function identically (e.g., both "a[7] = 0" and "b[7] = 0" are valid, as are both "strlen(a)" and "strlen(b)"), then using the sizeof() operator on each of them should return similar results. However, that isn't the case, as sizeof(a) gives us the size of an array while sizeof(b) gives us the size of a pointer.
It would make more sense if sizeof(a[]) returned the size of the array while sizeof(a) and sizeof(b) both returned the size of a pointer. As it presently works, sizeof() is a somewhat scary operator to use. I usually end up using a printf() to verify that it is giving me the size of what I want the size of rather than assume I know what it is doing.
You should use a passfile as well as a password. Makes it much harder for an attacker because something like a hardware keylogger or audio analysis to recover keystrokes can't see which file you selected. When it comes to breaking your key there is no way to know after the fact that a keyfile was used, so they will probably waste a large amount of time trying a dictionary attack on the password before even realizing that they need to also try any of the 100,000+ files on your computer as well. That is assuming you used a file on your computer, if it was on an external drive they didn't collect when they grabbed it they are screwed. Keep a few corrupt USB flash drives around just to make the wonder if they had it but broke it.
const int one = 65536; (Silvermoon, Texture.cs)
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I don't think you understand whats going on. PBKDF has absolutely nothing to do with 'protecting' your password. Its done because passwords suck ass for encryption keys.
TrueCrypt is taking your password and turning it into something USEFUL as a key for encryption, not 'protecting it'.
Standard passwords are pathetically low on entropy, a full twitter or SMS post is still not 256 bits of useful entropy, and its unlikely your passwords are anywhere near that. I admit I don't know your password, but if you're only using the standard character set, I can safely say its pathetically low on entropy. You need full binary keys generated from good random sources, but you'll never remember that, will you? Imaging trying to type it somewhere.
What the hashing does is takes your password and contorts it into a larger key that is more useful than whatever pathetic string of text you throw at it. It does so in such a way that, like all hashing processes are supposed to, you can't go backwards because bits are discarded along the way.
2000 rounds is pretty low, but thats only a tiny small part of the encryption/decryption process. And your password (as I understand true crypt) really just projects are larger private key, which is what is actually used for encryption. Its been a while since I've looked at or used TrueCrypt, so I may be wrong about that last particular bit.
For a full description: http://en.wikipedia.org/wiki/P...
I do write encryption software for a living. And again, its not about protecting your password or making it harder to guess, its about turning your crappy password into a useful encryption key, nothing more.
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I don't do this for a living, but I'm not totally ignorant about this topic. TrueCrypt does a poor job strengthening passwords. TC's users would be far better protected if TC ran something even as lame as PBKDF2 for a full second, with rounds somewhere in the 100's of thousands or millions. Not only does TC do a poor job protecting my data, but when an attacker does manage to guess a user's low-entropy password, he can then try that password all over the place to see where else the user has used it. This is why I say that the user's password is at risk due to TC, not just the data TC encrypts.
To give TC some credit, OpenSSL has the same lame password strengthening as TC, putting id_rsa passphrases at risk, in addition to the user's private key. So, there seems to be plenty of lameness to go around. I hear that a Bcrypt option is in the bleeding edge version of OpenSSL. I which they'd push out that patch along with the Heartbleed fix.
Celebrate failure, and then learn from it - Nolan Bushnell