Entries Tagged "encryption"

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Encrypting Windows Hard Drives

Encrypting your Windows hard drives is trivially easy; choosing which program to use is annoyingly difficult. I still use Windows—yes, I know, don’t even start—and have intimate experience with this issue.

Historically, I used PGP Disk. I used it because I knew and trusted the designers. I even used it after Symantec bought the company. But big companies are always suspect, because there are a lot of ways for governments to manipulate them.

Then, I used TrueCrypt. I used it because it was open source. But the anonymous developers weirdly abdicated in 2014 when Microsoft released Windows 8. I stuck with the program for a while, saying:

For Windows, the options are basically BitLocker, Symantec’s PGP Disk, and TrueCrypt. I choose TrueCrypt as the least bad of all the options.

But soon after that, despite the public audit of TrueCrypt, I bailed for BitLocker.

BitLocker is Microsoft’s native file encryption program. Yes, it’s from a big company. But it was designed by my colleague and friend Niels Ferguson, whom I trust. (Here’s Niels’s statement from 2006 on back doors.) It was a snap decision; much had changed since 2006. (Here I am in March speculating about an NSA back door in BitLocker.) Specifically, Microsoft made a bunch of changes in BitLocker for Windows 8, including removing something Niels designed called the “Elephant Diffuser.”

The Intercept’s Micah Lee recently recommended BitLocker and got a lot of pushback from the security community. Last week, he published more research and explanation about the trade-offs. It’s worth reading. Microsoft told him they removed the Elephant Diffuser for performance reasons. And I agree with his ultimate conclusion:

Based on what I know about BitLocker, I think it’s perfectly fine for average Windows users to rely on, which is especially convenient considering it comes with many PCs. If it ever turns out that Microsoft is willing to include a backdoor in a major feature of Windows, then we have much bigger problems than the choice of disk encryption software anyway.

Whatever you choose, if trusting a proprietary operating system not to be malicious doesn’t fit your threat model, maybe it’s time to switch to Linux.

Micah also nicely explains how TrueCrypt is becoming antiquated, and not keeping up with Microsoft’s file system changes.

Lately, I am liking an obscure program called BestCrypt, by a Finnish company called Jetico. Micah quotes me:

Considering Schneier has been outspoken for decades about the importance of open source cryptography, I asked if he recommends that other people use BestCrypt, even though it’s proprietary. “I do recommend BestCrypt,” Schneier told me, “because I have met people at the company and I have a good feeling about them. Of course I don’t know for sure; this business is all about trust. But right now, given what I know, I trust them.”

I know it’s not a great argument. But, again, I’m trying to find the least bad option. And in the end, you either have to write your own software or trust someone else to write it for you.

But, yes, this should be an easier decision.

Posted on June 15, 2015 at 6:31 AM • View Comments

Eighth Movie-Plot Threat Contest Winner

On April 1, I announced the Eighth Movie-Plot Threat Contest:

I want a movie-plot threat that shows the evils of encryption. (For those who don’t know, a movie-plot threat is a scary-threat story that would make a great movie, but is much too specific to build security policies around. Contest history here.) We’ve long heard about the evils of the Four Horsemen of the Internet Apocalypse—terrorists, drug dealers, kidnappers, and child pornographers. (Or maybe they’re terrorists, pedophiles, drug dealers, and money launderers; I can never remember.) Try to be more original than that. And nothing too science fictional; today’s technology or presumed technology only.

On May 14, I announced the five semifinalists. The votes are in, and the winner is TonyK:

November 6 2020, the morning of the presidential election. This will be the first election where votes can be cast from smart phones and laptops. A record turnout is expected.

There is much excitement as live results are being displayed all over the place. Twitter, television, apps and websites are all displaying the vote counts. It is a close race between the leading candidates until about 9 am when a third candidate starts to rapidly close the gap. He was an unknown independent that had suspected ties to multiple terrorist organizations. There was outrage when he got on to the ballot, but it had quickly died down when he put forth no campaign effort.

By 11 am the independent was predicted to win, and the software called it for him at 3:22 pm.

At 4 the CEO of the software maker was being interviewed on CNN. There were accusations of everything from bribery to bugs to hackers being responsible for the results. Demands were made for audits and recounts. Some were even asking for the data to be made publicly available. The CEO calmly explained that there could be no audit or recount. The system was encrypted end to end and all the votes were cryptographically anonymized.

The interviewer was stunned and sat there in silence. When he eventually spoke, he said “We just elected a terrorist as the President of the United States.”

For the record, Nick P was a close runner-up.

Congratulations, TonyK. Contact me by e-mail, and I’ll send you your fabulous prizes.

Previous contests.

EDITED TO ADD (6/14): Slashdot thread.

Posted on June 13, 2015 at 12:11 PM • View Comments

UN Report on the Value of Encryption to Freedom Worldwide

The United Nation’s Office of the High Commissioner released a report on the value of encryption and anonymity to the world:

Summary: In the present report, submitted in accordance with Human Rights Council resolution 25/2, the Special Rapporteur addresses the use of encryption and anonymity in digital communications. Drawing from research on international and national norms and jurisprudence, and the input of States and civil society, the report concludes that encryption and anonymity enable individuals to exercise their rights to freedom of opinion and expression in the digital age and, as such, deserve strong protection.

Here’s the bottom line:

60. States should not restrict encryption and anonymity, which facilitate and often enable the rights to freedom of opinion and expression. Blanket prohibitions fail to be necessary and proportionate. States should avoid all measures that weaken the security that individuals may enjoy online, such as backdoors, weak encryption standards and key escrows. In addition, States should refrain from making the identification of users a condition for access to digital communications and online services and requiring SIM card registration for mobile users. Corporate actors should likewise consider their own policies that restrict encryption and anonymity (including through the use of pseudonyms). Court-ordered decryption, subject to domestic and international law, may only be permissible when it results from transparent and publicly accessible laws applied solely on a targeted, case-by-case basis to individuals (i.e., not to a mass of people) and subject to judicial warrant and the protection of due process rights of individuals.

One news report called this “wishy-washy when it came to government-mandated backdoors to undermine encryption,” but I don’t see that. Government mandated backdoors, key escrow, and weak encryption are all bad. Corporations should offer their users strong encryption and anonymity. Any systems that still leave corporations with the keys and/or the data—and there are going to be lots of them—should only give them up to the government in the face of an individual and lawful court order.

I think the principles are reasonable.

Posted on May 29, 2015 at 7:49 AM • View Comments

The Logjam (and Another) Vulnerability against Diffie-Hellman Key Exchange

Logjam is a new attack against the Diffie-Hellman key-exchange protocol used in TLS. Basically:

The Logjam attack allows a man-in-the-middle attacker to downgrade vulnerable TLS connections to 512-bit export-grade cryptography. This allows the attacker to read and modify any data passed over the connection. The attack is reminiscent of the FREAK attack, but is due to a flaw in the TLS protocol rather than an implementation vulnerability, and attacks a Diffie-Hellman key exchange rather than an RSA key exchange. The attack affects any server that supports DHE_EXPORT ciphers, and affects all modern web browsers. 8.4% of the Top 1 Million domains were initially vulnerable.

Here’s the academic paper.

One of the problems with patching the vulnerability is that it breaks things:

On the plus side, the vulnerability has largely been patched thanks to consultation with tech companies like Google, and updates are available now or coming soon for Chrome, Firefox and other browsers. The bad news is that the fix rendered many sites unreachable, including the main website at the University of Michigan, which is home to many of the researchers that found the security hole.

This is a common problem with version downgrade attacks; patching them makes you incompatible with anyone who hasn’t patched. And it’s the vulnerability the media is focusing on.

Much more interesting is the other vulnerability that the researchers found:

Millions of HTTPS, SSH, and VPN servers all use the same prime numbers for Diffie-Hellman key exchange. Practitioners believed this was safe as long as new key exchange messages were generated for every connection. However, the first step in the number field sieve—the most efficient algorithm for breaking a Diffie-Hellman connection—is dependent only on this prime. After this first step, an attacker can quickly break individual connections.

The researchers believe the NSA has been using this attack:

We carried out this computation against the most common 512-bit prime used for TLS and demonstrate that the Logjam attack can be used to downgrade connections to 80% of TLS servers supporting DHE_EXPORT. We further estimate that an academic team can break a 768-bit prime and that a nation-state can break a 1024-bit prime. Breaking the single, most common 1024-bit prime used by web servers would allow passive eavesdropping on connections to 18% of the Top 1 Million HTTPS domains. A second prime would allow passive decryption of connections to 66% of VPN servers and 26% of SSH servers. A close reading of published NSA leaks shows that the agency’s attacks on VPNs are consistent with having achieved such a break.

Remember James Bamford’s 2012 comment about the NSA’s cryptanalytic capabilities:

According to another top official also involved with the program, the NSA made an enormous breakthrough several years ago in its ability to cryptanalyze, or break, unfathomably complex encryption systems employed by not only governments around the world but also many average computer users in the US. The upshot, according to this official: “Everybody’s a target; everybody with communication is a target.”

[…]

The breakthrough was enormous, says the former official, and soon afterward the agency pulled the shade down tight on the project, even within the intelligence community and Congress. “Only the chairman and vice chairman and the two staff directors of each intelligence committee were told about it,” he says. The reason? “They were thinking that this computing breakthrough was going to give them the ability to crack current public encryption.”

And remember Director of National Intelligence James Clapper’s introduction to the 2013 “Black Budget“:

Also, we are investing in groundbreaking cryptanalytic capabilities to defeat adversarial cryptography and exploit internet traffic.

It’s a reasonable guess that this is what both Bamford’s source and Clapper are talking about. It’s an attack that requires a lot of precomputation—just the sort of thing a national intelligence agency would go for.

But that requirement also speaks to its limitations. The NSA isn’t going to put this capability at collection points like Room 641A at AT&T’s San Francisco office: the precomputation table is too big, and the sensitivity of the capability is too high. More likely, an analyst identifies a target through some other means, and then looks for data by that target in databases like XKEYSCORE. Then he sends whatever ciphertext he finds to the Cryptanalysis and Exploitation Services (CES) group, which decrypts it if it can using this and other techniques.

Ross Anderson wrote about this earlier this month, almost certainly quoting Snowden:

As for crypto capabilities, a lot of stuff is decrypted automatically on ingest (e.g. using a “stolen cert”, presumably a private key obtained through hacking). Else the analyst sends the ciphertext to CES and they either decrypt it or say they can’t.

The analysts are instructed not to think about how this all works. This quote also applied to NSA employees:

Strict guidelines were laid down at the GCHQ complex in Cheltenham, Gloucestershire, on how to discuss projects relating to decryption. Analysts were instructed: “Do not ask about or speculate on sources or methods underpinning Bullrun.”

I remember the same instructions in documents I saw about the NSA’s CES.

Again, the NSA has put surveillance ahead of security. It never bothered to tell us that many of the “secure” encryption systems we were using were not secure. And we don’t know what other national intelligence agencies independently discovered and used this attack.

The good news is now that we know reusing prime numbers is a bad idea, we can stop doing it.

EDITED TO ADD: The DH precomputation easily lends itself to custom ASIC design, and is something that pipelines easily. Using BitCoin mining hardware as a rough comparison, this means a couple orders of magnitude speedup.

EDITED TO ADD (5/23): Good analysis of the cryptography.

EDITED TO ADD (5/24): Good explanation by Matthew Green.

Posted on May 21, 2015 at 6:30 AM • View Comments

Eighth Movie-Plot Threat Contest Semifinalists

On April 1, I announced the Eighth Movie Plot Threat Contest: demonstrate the evils of encryption.

Not a whole lot of good submissions this year. Possibly this contest has run its course, and there’s not a whole lot of interest left. On the other hand, it’s heartening to know that there aren’t a lot of encryption movie-plot threats out there.

Anyway, here are the semifinalists.

  1. Child pornographers.
  2. Bombing the NSA.
  3. Torture.
  4. Terrorists and a vaccine.
  5. Election systems.

Cast your vote by number here; voting closes at the end of the month.

Contest.

Previous contests.

Posted on May 14, 2015 at 11:26 PM • View Comments

More on the NSA's Capabilities

Ross Anderson summarizes a meeting in Princeton where Edward Snowden was “present.”

Third, the leaks give us a clear view of an intelligence analyst’s workflow. She will mainly look in Xkeyscore which is the Google of 5eyes comint; it’s a federated system hoovering up masses of stuff not just from 5eyes own assets but from other countries where the NSA cooperates or pays for access. Data are “ingested” into a vast rolling buffer; an analyst can run a federated search, using a selector (such as an IP address) or fingerprint (something that can be matched against the traffic). There are other such systems: “Dancing oasis” is the middle eastern version. Some xkeyscore assets are actually compromised third-party systems; there are multiple cases of rooted SMS servers that are queried in place and the results exfiltrated. Others involve vast infrastructure, like Tempora. If data in Xkeyscore are marked as of interest, they’re moved to Pinwale to be memorialised for 5+ years. This is one function of the MDRs (massive data repositories, now more tactfully renamed mission data repositories) like Utah. At present storage is behind ingestion. Xkeyscore buffer times just depend on volumes and what storage they managed to install, plus what they manage to filter out.

As for crypto capabilities, a lot of stuff is decrypted automatically on ingest (e.g. using a “stolen cert,” presumably a private key obtained through hacking). Else the analyst sends the ciphertext to CES and they either decrypt it or say they can’t. There’s no evidence of a “wow” cryptanalysis; it was key theft, or an implant, or a predicted RNG or supply-chain interference. Cryptanalysis has been seen of RC4, but not of elliptic curve crypto, and there’s no sign of exploits against other commonly used algorithms. Of course, the vendors of some products have been coopted, notably skype. Homegrown crypto is routinely problematic, but properly implemented crypto keeps the agency out; gpg ciphertexts with RSA 1024 were returned as fails.

[…]

What else might we learn from the disclosures when designing and implementing crypto? Well, read the disclosures and use your brain. Why did GCHQ bother stealing all the SIM card keys for Iceland from Gemalto, unless they have access to the local GSM radio links? Just look at the roof panels on US or UK embassies, that look like concrete but are actually transparent to RF. So when designing a protocol ask yourself whether a local listener is a serious consideration.

[…]

On the policy front, one of the eye-openers was the scale of intelligence sharing—it’s not just 5 eyes, but 15 or 35 or even 65 once you count all the countries sharing stuff with the NSA. So how does governance work? Quite simply, the NSA doesn’t care about policy. Their OGC has 100 lawyers whose job is to “enable the mission”; to figure out loopholes or new interpretations of the law that let stuff get done. How do you restrain this? Could you use courts in other countries, that have stronger human-rights law? The precedents are not encouraging. New Zealand’s GCSB was sharing intel with Bangladesh agencies while the NZ government was investigating them for human-rights abuses. Ramstein in Germany is involved in all the drone killings, as fibre is needed to keep latency down low enough for remote vehicle pilots. The problem is that the intelligence agencies figure out ways to shield the authorities from culpability, and this should not happen.

[…]

The spooks’ lawyers play games saying for example that they dumped content, but if you know IP address and file size you often have it; and IP address is a good enough pseudonym for most intel / LE use. They deny that they outsource to do legal arbitrage (e.g. NSA spies on Brits and GCHQ returns the favour by spying on Americans). Are they telling the truth? In theory there will be an MOU between NSA and the partner agency stipulating respect for each others’ laws, but there can be caveats, such as a classified version which says “this is not a binding legal document.” The sad fact is that law and legislators are losing the capability to hold people in the intelligence world to account, and also losing the appetite for it.

Worth reading in full.

Posted on May 11, 2015 at 6:26 AM •

The Further Democratization of QUANTUM

From my book Data and Goliath:

…when I was working with the Guardian on the Snowden documents, the one top-secret program the NSA desperately did not want us to expose was QUANTUM. This is the NSA’s program for what is called packet injection­—basically, a technology that allows the agency to hack into computers. Turns out, though, that the NSA was not alone in its use of this technology. The Chinese government uses packet injection to attack computers. The cyberweapons manufacturer Hacking Team sells packet injection technology to any government willing to pay for it. Criminals use it. And there are hacker tools that give the capability to individuals as well. All of these existed before I wrote about QUANTUM. By using its knowledge to attack others rather than to build up the Internet’s defenses, the NSA has worked to ensure that anyone can use packet injection to hack into computers.

And that’s true. China’s Great Cannon uses QUANTUM. The ability to inject packets into the backbone is a powerful attack technology, and one that is increasingly being used by different attackers.

I continued:

Even when technologies are developed inside the NSA, they don’t remain exclusive for long. Today’s top-secret programs become tomorrow’s PhD theses and the next day’s hacker tools.

I could have continued with “and the next day’s homework assignment,” because Michalis Polychronakis at Stony Book University has just assigned building a rudimentary QUANTUM tool as a homework assignment. It’s basically sniff, regexp match, swap sip/sport/dip/dport/syn/ack, set ack and push flags, and add the payload to create the malicious reply. Shouldn’t take more than a few hours to get it working. Of course, it would take a lot more to make it as sophisticated and robust as what the NSA and China have at their disposal, but the moral is that the tool is now in the hands of anyone who wants it. We need to make the Internet secure against this kind of attack instead of pretending that only the “good guys” can use it effectively.

End-to-end encryption is the solution. Nicholas Weaver wrote:

The only self defense from all of the above is universal encryption. Universal encryption is difficult and expensive, but unfortunately necessary.

Encryption doesn’t just keep our traffic safe from eavesdroppers, it protects us from attack. DNSSEC validation protects DNS from tampering, while SSL armors both email and web traffic.

There are many engineering and logistic difficulties involved in encrypting all traffic on the internet, but its one we must overcome if we are to defend ourselves from the entities that have weaponized the backbone.

Yes.

And this is true in general. We have one network in the world today. Either we build our communications infrastructure for surveillance, or we build it for security. Either everyone gets to spy, or no one gets to spy. That’s our choice, with the Internet, with cell phone networks, with everything.

Posted on April 24, 2015 at 8:55 AM • View Comments

Can the NSA Break Microsoft's BitLocker?

The Intercept has a new story on the CIA’s—yes, the CIA, not the NSA—efforts to break encryption. These are from the Snowden documents, and talk about a conference called the Trusted Computing Base Jamboree. There are some interesting documents associated with the article, but not a lot of hard information.

There’s a paragraph about Microsoft’s BitLocker, the encryption system used to protect MS Windows computers:

Also presented at the Jamboree were successes in the targeting of Microsoft’s disk encryption technology, and the TPM chips that are used to store its encryption keys. Researchers at the CIA conference in 2010 boasted about the ability to extract the encryption keys used by BitLocker and thus decrypt private data stored on the computer. Because the TPM chip is used to protect the system from untrusted software, attacking it could allow the covert installation of malware onto the computer, which could be used to access otherwise encrypted communications and files of consumers. Microsoft declined to comment for this story.

This implies that the US intelligence community—I’m guessing the NSA here—can break BitLocker. The source document, though, is much less definitive about it.

Power analysis, a side-channel attack, can be used against secure devices to non-invasively extract protected cryptographic information such as implementation details or secret keys. We have employed a number of publically known attacks against the RSA cryptography found in TPMs from five different manufacturers. We will discuss the details of these attacks and provide insight into how private TPM key information can be obtained with power analysis. In addition to conventional wired power analysis, we will present results for extracting the key by measuring electromagnetic signals emanating from the TPM while it remains on the motherboard. We will also describe and present results for an entirely new unpublished attack against a Chinese Remainder Theorem (CRT) implementation of RSA that will yield private key information in a single trace.

The ability to obtain a private TPM key not only provides access to TPM-encrypted data, but also enables us to circumvent the root-of-trust system by modifying expected digest values in sealed data. We will describe a case study in which modifications to Microsoft’s Bitlocker encrypted metadata prevents software-level detection of changes to the BIOS.

Differential power analysis is a powerful cryptanalytic attack. Basically, it examines a chip’s power consumption while it performs encryption and decryption operations and uses that information to recover the key. What’s important here is that this is an attack to extract key information from a chip while it is running. If the chip is powered down, or if it doesn’t have the key inside, there’s no attack.

I don’t take this to mean that the NSA can take a BitLocker-encrypted hard drive and recover the key. I do take it to mean that the NSA can perform a bunch of clever hacks on a BitLocker-encrypted hard drive while it is running. So I don’t think this means that BitLocker is broken.

But who knows? We do know that the FBI pressured Microsoft to add a backdoor to BitLocker in 2005. I believe that was unsuccessful.

More than that, we don’t know.

EDITED TO ADD (3/12): Starting with Windows 8, Microsoft removed the Elephant Diffuser from BitLocker. I see no reason to remove it other than to make the encryption weaker.

Posted on March 10, 2015 at 2:34 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.