Entries Tagged "backdoors"

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Backdoors Won't Solve Comey's Going Dark Problem

At the Aspen Security Forum two weeks ago, James Comey (and others) explicitly talked about the “going dark” problem, describing the specific scenario they are concerned about. Maybe others have heard the scenario before, but it was a first for me. It centers around ISIL operatives abroad and ISIL-inspired terrorists here in the US. The FBI knows who the Americans are, can get a court order to carry out surveillance on their communications, but cannot eavesdrop on the conversations, because they are encrypted. They can get the metadata, so they know who is talking to who, but they can’t find out what’s being said.

“ISIL’s M.O. is to broadcast on Twitter, get people to follow them, then move them to Twitter Direct Messaging” to evaluate if they are a legitimate recruit, he said. “Then they’ll move them to an encrypted mobile-messaging app so they go dark to us.”

[…]

The FBI can get court-approved access to Twitter exchanges, but not to encrypted communication, Comey said. Even when the FBI demonstrates probable cause and gets a judicial order to intercept that communication, it cannot break the encryption for technological reasons, according to Comey.

If this is what Comey and the FBI are actually concerned about, they’re getting bad advice—because their proposed solution won’t solve the problem. Comey wants communications companies to give them the capability to eavesdrop on conversations without the conversants’ knowledge or consent; that’s the “backdoor” we’re all talking about. But the problem isn’t that most encrypted communications platforms are securely encrypted, or even that some are—the problem is that there exists at least one securely encrypted communications platform on the planet that ISIL can use.

Imagine that Comey got what he wanted. Imagine that iMessage and Facebook and Skype and everything else US-made had his backdoor. The ISIL operative would tell his potential recruit to use something else, something secure and non-US-made. Maybe an encryption program from Finland, or Switzerland, or Brazil. Maybe Mujahedeen Secrets. Maybe anything. (Sure, some of these will have flaws, and they’ll be identifiable by their metadata, but the FBI already has the metadata, and the better software will rise to the top.) As long as there is something that the ISIL operative can move them to, some software that the American can download and install on their phone or computer, or hardware that they can buy from abroad, the FBI still won’t be able to eavesdrop.

And by pushing these ISIL operatives to non-US platforms, they lose access to the metadata they otherwise have.

Convincing US companies to install backdoors isn’t enough; in order to solve this going dark problem, the FBI has to ensure that an American can only use backdoored software. And the only way to do that is to prohibit the use of non-backdoored software, which is the sort of thing that the UK’s David Cameron said he wanted for his country in January:

But the question is are we going to allow a means of communications which it simply isn’t possible to read. My answer to that question is: no, we must not.

And that, of course, is impossible. Jonathan Zittrain explained why. And Cory Doctorow outlined what trying would entail:

For David Cameron’s proposal to work, he will need to stop Britons from installing software that comes from software creators who are out of his jurisdiction. The very best in secure communications are already free/open source projects, maintained by thousands of independent programmers around the world. They are widely available, and thanks to things like cryptographic signing, it is possible to download these packages from any server in the world (not just big ones like Github) and verify, with a very high degree of confidence, that the software you’ve downloaded hasn’t been tampered with.

[…]

This, then, is what David Cameron is proposing:

* All Britons’ communications must be easy for criminals, voyeurs and foreign spies to intercept.

* Any firms within reach of the UK government must be banned from producing secure software.

* All major code repositories, such as Github and Sourceforge, must be blocked.

* Search engines must not answer queries about web-pages that carry secure software.

* Virtually all academic security work in the UK must cease—security research must only take place in proprietary research environments where there is no onus to publish one’s findings, such as industry R&D and the security services.

* All packets in and out of the country, and within the country, must be subject to Chinese-style deep-packet inspection and any packets that appear to originate from secure software must be dropped.

* Existing walled gardens (like IOs and games consoles) must be ordered to ban their users from installing secure software.

* Anyone visiting the country from abroad must have their smartphones held at the border until they leave.

* Proprietary operating system vendors (Microsoft and Apple) must be ordered to redesign their operating systems as walled gardens that only allow users to run software from an app store, which will not sell or give secure software to Britons.

* Free/open source operating systems—that power the energy, banking, ecommerce, and infrastructure sectors—must be banned outright.

As extreme as it reads, without all of that, the ISIL operative would be able to communicate securely with his potential American recruit. And all of this is not going to happen.

Last week, former NSA director Mike McConnell, former DHS secretary Michael Chertoff, and former deputy defense secretary William Lynn published a Washington Post op-ed opposing backdoors in encryption software. They wrote:

Today, with almost everyone carrying a networked device on his or her person, ubiquitous encryption provides essential security. If law enforcement and intelligence organizations face a future without assured access to encrypted communications, they will develop technologies and techniques to meet their legitimate mission goals.

I believe this is true. Already one is being talked about in the academic literature: lawful hacking.

Perhaps the FBI’s reluctance to accept this is based on their belief that all encryption software comes from the US, and therefore is under their influence. Back in the 1990s, during the first Crypto Wars, the US government had a similar belief. To convince them otherwise, George Washington University surveyed the cryptography market in 1999 and found that there were over 500 companies in 70 countries manufacturing or distributing non-US cryptography products. Maybe we need a similar study today.

This essay previously appeared on Lawfare.

Posted on July 31, 2015 at 6:08 AM • View Comments

The Risks of Mandating Backdoors in Encryption Products

Tuesday, a group of cryptographers and security experts released a major paper outlining the risks of government-mandated back-doors in encryption products: Keys Under Doormats: Mandating insecurity by requiring government access to all data and communications, by Hal Abelson, Ross Anderson, Steve Bellovin, Josh Benaloh, Matt Blaze, Whitfield Diffie, John Gilmore, Matthew Green, Susan Landau, Peter Neumann, Ron Rivest, Jeff Schiller, Bruce Schneier, Michael Specter, and Danny Weitzner.

Abstract: Twenty years ago, law enforcement organizations lobbied to require data and communication services to engineer their products to guarantee law enforcement access to all data. After lengthy debate and vigorous predictions of enforcement channels going dark, these attempts to regulate the emerging Internet were abandoned. In the intervening years, innovation on the Internet flourished, and law enforcement agencies found new and more effective means of accessing vastly larger quantities of data. Today we are again hearing calls for regulation to mandate the provision of exceptional access mechanisms. In this report, a group of computer scientists and security experts, many of whom participated in a 1997 study of these same topics, has convened to explore the likely effects of imposing extraordinary access mandates. We have found that the damage that could be caused by law enforcement exceptional access requirements would be even greater today than it would have been 20 years ago. In the wake of the growing economic and social cost of the fundamental insecurity of today’s Internet environment, any proposals that alter the security dynamics online should be approached with caution. Exceptional access would force Internet system developers to reverse forward secrecy design practices that seek to minimize the impact on user privacy when systems are breached. The complexity of today’s Internet environment, with millions of apps and globally connected services, means that new law enforcement requirements are likely to introduce unanticipated, hard to detect security flaws. Beyond these and other technical vulnerabilities, the prospect of globally deployed exceptional access systems raises difficult problems about how such an environment would be governed and how to ensure that such systems would respect human rights and the rule of law.

It’s already had a big impact on the debate. It was mentioned several times during yesterday’s Senate hearing on the issue (see here).

Three blog posts by authors. Four different news articles, and this analysis of how the New York Times article changed. Also, a New York Times editorial.

EDITED TO ADD (7/9): Peter Swire’s Senate testimony is worth reading.

EDITED TO ADD (7/10): Good article on these new crypto wars.

EDITED TO ADF (7/14): Two rebuttals, neither very convincing.

Posted on July 9, 2015 at 6:31 AM • View Comments

What is the DoD's Position on Backdoors in Security Systems?

In May, Admiral James A. Winnefeld, Jr., vice-chairman of the Joint Chiefs of Staff, gave an address at the Joint Service Academies Cyber Security Summit at West Point. After he spoke for twenty minutes on the importance of Internet security and a good national defense, I was able to ask him a question (32:42 mark) about security versus surveillance:

Bruce Schneier: I’d like to hear you talk about this need to get beyond signatures and the more robust cyber defense and ask the industry to provide these technologies to make the infrastructure more secure. My question is, the only definition of “us” that makes sense is the world, is everybody. Any technologies that we’ve developed and built will be used by everyone—nation-state and non-nation-state. So anything we do to increase our resilience, infrastructure, and security will naturally make Admiral Rogers’s both intelligence and attack jobs much harder. Are you okay with that?

Admiral James A. Winnefeld: Yes. I think Mike’s okay with that, also. That’s a really, really good question. We call that IGL. Anyone know what IGL stands for? Intel gain-loss. And there’s this constant tension between the operational community and the intelligence community when a military action could cause the loss of a critical intelligence node. We live this every day. In fact, in ancient times, when we were collecting actual signals in the air, we would be on the operational side, “I want to take down that emitter so it’ll make it safer for my airplanes to penetrate the airspace,” and they’re saying, “No, you’ve got to keep that emitter up, because I’m getting all kinds of intelligence from it.” So this is a familiar problem. But I think we all win if our networks are more secure. And I think I would rather live on the side of secure networks and a harder problem for Mike on the intelligence side than very vulnerable networks and an easy problem for Mike. And part of that—it’s not only the right thing do, but part of that goes to the fact that we are more vulnerable than any other country in the world, on our dependence on cyber. I’m also very confident that Mike has some very clever people working for him. He might actually still be able to get some work done. But it’s an excellent question. It really is.

It’s a good answer, and one firmly on the side of not introducing security vulnerabilities, backdoors, key-escrow systems, or anything that weakens Internet systems. It speaks to what I have seen as a split in the Second Crypto War, between the NSA and the FBI on building secure systems versus building systems with surveillance capabilities.

I have written about this before:

But here’s the problem: technological capabilities cannot distinguish based on morality, nationality, or legality; if the US government is able to use a backdoor in a communications system to spy on its enemies, the Chinese government can use the same backdoor to spy on its dissidents.

Even worse, modern computer technology is inherently democratizing. Today’s NSA secrets become tomorrow’s PhD theses and the next day’s hacker tools. As long as we’re all using the same computers, phones, social networking platforms, and computer networks, a vulnerability that allows us to spy also allows us to be spied upon.

We can’t choose a world where the US gets to spy but China doesn’t, or even a world where governments get to spy and criminals don’t. We need to choose, as a matter of policy, communications systems that are secure for all users, or ones that are vulnerable to all attackers. It’s security or surveillance.

NSA Director Admiral Mike Rogers was in the audience (he spoke earlier), and I saw him nodding at Winnefeld’s answer. Two weeks later, at CyCon in Tallinn, Rogers gave the opening keynote, and he seemed to be saying the opposite.

“Can we create some mechanism where within this legal framework there’s a means to access information that directly relates to the security of our respective nations, even as at the same time we are mindful we have got to protect the rights of our individual citizens?”

[…]

Rogers said a framework to allow law enforcement agencies to gain access to communications is in place within the phone system in the United States and other areas, so “why can’t we create a similar kind of framework within the internet and the digital age?”

He added: “I certainly have great respect for those that would argue that they most important thing is to ensure the privacy of our citizens and we shouldn’t allow any means for the government to access information. I would argue that’s not in the nation’s best long term interest, that we’ve got to create some structure that should enable us to do that mindful that it has to be done in a legal way and mindful that it shouldn’t be something arbitrary.”

Does Winnefeld know that Rogers is contradicting him? Can someone ask JCS about this?

Posted on June 24, 2015 at 7:42 AM • View Comments

History of the First Crypto War

As we’re all gearing up to fight the Second Crypto War over governments’ demands to be able to back-door any cryptographic system, it pays for us to remember the history of the First Crypto War. The Open Technology Institute has written the story of those years in the mid-1990s.

The act that truly launched the Crypto Wars was the White House’s introduction of the “Clipper Chip” in 1993. The Clipper Chip was a state-of-the-art microchip developed by government engineers which could be inserted into consumer hardware telephones, providing the public with strong cryptographic tools without sacrificing the ability of law enforcement and intelligence agencies to access unencrypted versions of those communications. The technology relied on a system of “key escrow,” in which a copy of each chip’s unique encryption key would be stored by the government. Although White House officials mobilized both political and technical allies in support of the proposal, it faced immediate backlash from technical experts, privacy advocates, and industry leaders, who were concerned about the security and economic impact of the technology in addition to obvious civil liberties concerns. As the battle wore on throughout 1993 and into 1994, leaders from across the political spectrum joined the fray, supported by a broad coalition that opposed the Clipper Chip. When computer scientist Matt Blaze discovered a flaw in the system in May 1994, it proved to be the final death blow: the Clipper Chip was dead.

Nonetheless, the idea that the government could find a palatable way to access the keys to encrypted communications lived on throughout the 1990s. Many policymakers held onto hopes that it was possible to securely implement what they called “software key escrow” to preserve access to phone calls, emails, and other communications and storage applications. Under key escrow schemes, a government-certified third party would keep a “key” to every device. But the government’s shift in tactics ultimately proved unsuccessful; the privacy, security, and economic concerns continued to outweigh any potential benefits. By 1997, there was an overwhelming amount of evidence against moving ahead with any key escrow schemes.

The Second Crypto War is going to be harder and nastier, and I am less optimistic that strong cryptography will win in the short term.

Posted on June 22, 2015 at 1:35 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

How the CIA Might Target Apple's XCode

The Intercept recently posted a story on the CIA’s attempts to hack the iOS operating system. Most interesting was the speculation that it hacked XCode, which would mean that any apps developed using that tool would be compromised.

The security researchers also claimed they had created a modified version of Apple’s proprietary software development tool, Xcode, which could sneak surveillance backdoors into any apps or programs created using the tool. Xcode, which is distributed by Apple to hundreds of thousands of developers, is used to create apps that are sold through Apple’s App Store.

The modified version of Xcode, the researchers claimed, could enable spies to steal passwords and grab messages on infected devices. Researchers also claimed the modified Xcode could “force all iOS applications to send embedded data to a listening post.” It remains unclear how intelligence agencies would get developers to use the poisoned version of Xcode.

Researchers also claimed they had successfully modified the OS X updater, a program used to deliver updates to laptop and desktop computers, to install a “keylogger.”

It’s a classic application of Ken Thompson’s classic 1984 paper, “Reflections on Trusting Trust,” and a very nasty attack. Dan Wallach speculates on how this might work.

Posted on March 16, 2015 at 7:38 AM • View Comments

FREAK: Security Rollback Attack Against SSL

This week, we learned about an attack called “FREAK”—”Factoring Attack on RSA-EXPORT Keys”—that can break the encryption of many websites. Basically, some sites’ implementations of secure sockets layer technology, or SSL, contain both strong encryption algorithms and weak encryption algorithms. Connections are supposed to use the strong algorithms, but in many cases an attacker can force the website to use the weaker encryption algorithms and then decrypt the traffic. From Ars Technica:

In recent days, a scan of more than 14 million websites that support the secure sockets layer or transport layer security protocols found that more than 36 percent of them were vulnerable to the decryption attacks. The exploit takes about seven hours to carry out and costs as little as $100 per site.

This is a general class of attack I call “security rollback” attacks. Basically, the attacker forces the system users to revert to a less secure version of their protocol. Think about the last time you used your credit card. The verification procedure involved the retailer’s computer connecting with the credit card company. What if you snuck around to the back of the building and severed the retailer’s phone lines? Most likely, the retailer would have still accepted your card, but defaulted to making a manual impression of it and maybe looking at your signature. The result: you’ll have a much easier time using a stolen card.

In this case, the security flaw was designed in deliberately. Matthew Green writes:

Back in the early 1990s when SSL was first invented at Netscape Corporation, the United States maintained a rigorous regime of export controls for encryption systems. In order to distribute crypto outside of the U.S., companies were required to deliberately “weaken” the strength of encryption keys. For RSA encryption, this implied a maximum allowed key length of 512 bits.

The 512-bit export grade encryption was a compromise between dumb and dumber. In theory it was designed to ensure that the NSA would have the ability to “access” communications, while allegedly providing crypto that was still “good enough” for commercial use. Or if you prefer modern terms, think of it as the original “golden master key.”

The need to support export-grade ciphers led to some technical challenges. Since U.S. servers needed to support both strong and weak crypto, the SSL designers used a “cipher suite” negotiation mechanism to identify the best cipher both parties could support. In theory this would allow “strong” clients to negotiate “strong” ciphersuites with servers that supported them, while still providing compatibility to the broken foreign clients.

And that’s the problem. The weak algorithms are still there, and can be exploited by attackers.

Fixes are coming. Companies like Apple are quickly rolling out patches. But the vulnerability has been around for over a decade, and almost has certainly used by national intelligence agencies and criminals alike.

This is the generic problem with government-mandated backdoors, key escrow, “golden keys,” or whatever you want to call them. We don’t know how to design a third-party access system that checks for morality; once we build in such access, we then have to ensure that only the good guys can do it. And we can’t. Or, to quote the Economist: “…mathematics applies to just and unjust alike; a flaw that can be exploited by Western governments is vulnerable to anyone who finds it.”

This essay previously appeared on the Lawfare blog.

EDITED TO ADD: Microsoft Windows is vulnerable.

Posted on March 6, 2015 at 10:46 AM • View Comments

"Surreptitiously Weakening Cryptographic Systems"

New paper: “Surreptitiously Weakening Cryptographic Systems,” by Bruce Schneier, Matthew Fredrikson, Tadayoshi Kohno, and Thomas Ristenpart.

Abstract: Revelations over the past couple of years highlight the importance of understanding malicious and surreptitious weakening of cryptographic systems. We provide an overview of this domain, using a number of historical examples to drive development of a weaknesses taxonomy. This allows comparing different approaches to sabotage. We categorize a broader set of potential avenues for weakening systems using this taxonomy, and discuss what future research is needed to provide sabotage-resilient cryptography.

EDITED TO ADD (3/3): News article.

Posted on February 25, 2015 at 6:09 AM • View Comments

More Crypto Wars II

FBI Director James Comey again called for an end to secure encryption by putting in a backdoor. Here’s his speech:

There is a misconception that building a lawful intercept solution into a system requires a so-called “back door,” one that foreign adversaries and hackers may try to exploit.

But that isn’t true. We aren’t seeking a back-door approach. We want to use the front door, with clarity and transparency, and with clear guidance provided by law. We are completely comfortable with court orders and legal process—front doors that provide the evidence and information we need to investigate crime and prevent terrorist attacks.

Cyber adversaries will exploit any vulnerability they find. But it makes more sense to address any security risks by developing intercept solutions during the design phase, rather than resorting to a patchwork solution when law enforcement comes knocking after the fact. And with sophisticated encryption, there might be no solution, leaving the government at a dead end—all in the name of privacy and network security.

I’m not sure why he believes he can have a technological means of access that somehow only works for people of the correct morality with the proper legal documents, but he seems to believe that’s possible. As Jeffrey Vagle and Matt Blaze point out, there’s no technical difference between Comey’s “front door” and a “back door.”

As in all of these sorts of speeches, Comey gave examples of crimes that could have been solved had only the police been able to decrypt the defendant’s phone. Unfortunately, none of the three stories is true. The Intercept tracked down each story, and none of them is actually a case where encryption foiled an investigation, arrest, or conviction:

In the most dramatic case that Comey invoked—the death of a 2-year-old Los Angeles girl—not only was cellphone data a non-issue, but records show the girl’s death could actually have been avoided had government agencies involved in overseeing her and her parents acted on the extensive record they already had before them.

In another case, of a Louisiana sex offender who enticed and then killed a 12-year-old boy, the big break had nothing to do with a phone: The murderer left behind his keys and a trail of muddy footprints, and was stopped nearby after his car ran out of gas.

And in the case of a Sacramento hit-and-run that killed a man and his girlfriend’s four dogs, the driver was arrested in a traffic stop because his car was smashed up, and immediately confessed to involvement in the incident.

[…]

His poor examples, however, were reminiscent of one cited by Ronald T. Hosko, a former assistant director of the FBI’s Criminal Investigative Division, in a widely cited—and thoroughly debunked—Washington Post opinion piece last month.

In that case, the Post was eventually forced to have Hosko rewrite the piece, with the following caveat appended:

Editors note: This story incorrectly stated that Apple and Google’s new encryption rules would have hindered law enforcement’s ability to rescue the kidnap victim in Wake Forest, N.C. This is not the case. The piece has been corrected.

Hadn’t Comey found anything better since then? In a question-and-answer session after his speech, Comey both denied trying to use scare stories to make his point—and admitted that he had launched a nationwide search for better ones, to no avail.

This is important. All the FBI talk about “going dark” and losing the ability to solve crimes is absolute bullshit. There is absolutely no evidence, either statistically or even anecdotally, that criminals are going free because of encryption.

So why are we even discussing the possibility to forcing companies to provide insecure encryption to their users and customers?

The EFF points out that companies are protected by law from being required to provide insecure security to make the FBI happy.

Sadly, I don’t think this is going to go away anytime soon.

My first post on these new Crypto Wars is here.

Posted on October 21, 2014 at 6:17 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.