Entries Tagged "encryption"

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Indistinguishability Obfuscation

Quanta magazine recently published a breathless article on indistinguishability obfuscation — calling it the “‘crown jewel’ of cryptography” — and saying that it had finally been achieved, based on a recently published paper. I want to add some caveats to the discussion.

Basically, obfuscation makes a computer program “unintelligible” by performing its functionality. Indistinguishability obfuscation is more relaxed. It just means that two different programs that perform the same functionality can’t be distinguished from each other. A good definition is in this paper.

This is a pretty amazing theoretical result, and one to be excited about. We can now do obfuscation, and we can do it using assumptions that make real-world sense. The proofs are kind of ugly, but that’s okay — it’s a start. What it means in theory is that we have a fundamental theoretical result that we can use to derive a whole bunch of other cryptographic primitives.

But — and this is a big one — this result is not even remotely close to being practical. We’re talking multiple days to perform pretty simple calculations, using massively large blocks of computer code. And this is likely to remain true for a very long time. Unless researchers increase performance by many orders of magnitude, nothing in the real world will make use of this work anytime soon.

But but, consider fully homomorphic encryption. It, too, was initially theoretically interesting and completely impractical. And now, after decades of work, it seems to be almost just-barely maybe approaching practically useful. This could very well be on the same trajectory, and perhaps in twenty to thirty years we will be celebrating this early theoretical result as the beginning of a new theory of cryptography.

Posted on November 23, 2020 at 6:04 AMView Comments

New Report on Police Decryption Capabilities

There is a new report on police decryption capabilities: specifically, mobile device forensic tools (MDFTs). Short summary: it’s not just the FBI that can do it.

This report documents the widespread adoption of MDFTs by law enforcement in the United States. Based on 110 public records requests to state and local law enforcement agencies across the country, our research documents more than 2,000 agencies that have purchased these tools, in all 50 states and the District of Columbia. We found that state and local law enforcement agencies have performed hundreds of thousands of cellphone extractions since 2015, often without a warrant. To our knowledge, this is the first time that such records have been widely disclosed.

Lots of details in the report. And in this news article:

At least 49 of the 50 largest U.S. police departments have the tools, according to the records, as do the police and sheriffs in small towns and counties across the country, including Buckeye, Ariz.; Shaker Heights, Ohio; and Walla Walla, Wash. And local law enforcement agencies that don’t have such tools can often send a locked phone to a state or federal crime lab that does.

[…]

The tools mostly come from Grayshift, an Atlanta company co-founded by a former Apple engineer, and Cellebrite, an Israeli unit of Japan’s Sun Corporation. Their flagship tools cost roughly $9,000 to $18,000, plus $3,500 to $15,000 in annual licensing fees, according to invoices obtained by Upturn.

Posted on October 23, 2020 at 8:47 AMView Comments

BlackBerry Phone Cracked

Australia is reporting that a BlackBerry device has been cracked after five years:

An encrypted BlackBerry device that was cracked five years after it was first seized by police is poised to be the key piece of evidence in one of the state’s longest-running drug importation investigations.

In April, new technology “capabilities” allowed authorities to probe the encrypted device….

No details about those capabilities.

Posted on August 3, 2020 at 11:54 AMView Comments

On the Twitter Hack

Twitter was hacked this week. Not a few people’s Twitter accounts, but all of Twitter. Someone compromised the entire Twitter network, probably by stealing the log-in credentials of one of Twitter’s system administrators. Those are the people trusted to ensure that Twitter functions smoothly.

The hacker used that access to send tweets from a variety of popular and trusted accounts, including those of Joe Biden, Bill Gates, and Elon Musk, as part of a mundane scam — stealing bitcoin — but it’s easy to envision more nefarious scenarios. Imagine a government using this sort of attack against another government, coordinating a series of fake tweets from hundreds of politicians and other public figures the day before a major election, to affect the outcome. Or to escalate an international dispute. Done well, it would be devastating.

Whether the hackers had access to Twitter direct messages is not known. These DMs are not end-to-end encrypted, meaning that they are unencrypted inside Twitter’s network and could have been available to the hackers. Those messages — between world leaders, industry CEOs, reporters and their sources, heath organizations — are much more valuable than bitcoin. (If I were a national-intelligence agency, I might even use a bitcoin scam to mask my real intelligence-gathering purpose.) Back in 2018, Twitter said it was exploring encrypting those messages, but it hasn’t yet.

Internet communications platforms — such as Facebook, Twitter, and YouTube — are crucial in today’s society. They’re how we communicate with one another. They’re how our elected leaders communicate with us. They are essential infrastructure. Yet they are run by for-profit companies with little government oversight. This is simply no longer sustainable. Twitter and companies like it are essential to our national dialogue, to our economy, and to our democracy. We need to start treating them that way, and that means both requiring them to do a better job on security and breaking them up.

In the Twitter case this week, the hacker’s tactics weren’t particularly sophisticated. We will almost certainly learn about security lapses at Twitter that enabled the hack, possibly including a SIM-swapping attack that targeted an employee’s cellular service provider, or maybe even a bribed insider. The FBI is investigating.

This kind of attack is known as a “class break.” Class breaks are endemic to computerized systems, and they’re not something that we as users can defend against with better personal security. It didn’t matter whether individual accounts had a complicated and hard-to-remember password, or two-factor authentication. It didn’t matter whether the accounts were normally accessed via a Mac or a PC. There was literally nothing any user could do to protect against it.

Class breaks are security vulnerabilities that break not just one system, but an entire class of systems. They might exploit a vulnerability in a particular operating system that allows an attacker to take remote control of every computer that runs on that system’s software. Or a vulnerability in internet-enabled digital video recorders and webcams that allows an attacker to recruit those devices into a massive botnet. Or a single vulnerability in the Twitter network that allows an attacker to take over every account.

For Twitter users, this attack was a double whammy. Many people rely on Twitter’s authentication systems to know that someone who purports to be a certain celebrity, politician, or journalist is really that person. When those accounts were hijacked, trust in that system took a beating. And then, after the attack was discovered and Twitter temporarily shut down all verified accounts, the public lost a vital source of information.

There are many security technologies companies like Twitter can implement to better protect themselves and their users; that’s not the issue. The problem is economic, and fixing it requires doing two things. One is regulating these companies, and requiring them to spend more money on security. The second is reducing their monopoly power.

The security regulations for banks are complex and detailed. If a low-level banking employee were caught messing around with people’s accounts, or if she mistakenly gave her log-in credentials to someone else, the bank would be severely fined. Depending on the details of the incident, senior banking executives could be held personally liable. The threat of these actions helps keep our money safe. Yes, it costs banks money; sometimes it severely cuts into their profits. But the banks have no choice.

The opposite is true for these tech giants. They get to decide what level of security you have on your accounts, and you have no say in the matter. If you are offered security and privacy options, it’s because they decided you can have them. There is no regulation. There is no accountability. There isn’t even any transparency. Do you know how secure your data is on Facebook, or in Apple’s iCloud, or anywhere? You don’t. No one except those companies do. Yet they’re crucial to the country’s national security. And they’re the rare consumer product or service allowed to operate without significant government oversight.

For example, President Donald Trump’s Twitter account wasn’t hacked as Joe Biden’s was, because that account has “special protections,” the details of which we don’t know. We also don’t know what other world leaders have those protections, or the decision process surrounding who gets them. Are they manual? Can they scale? Can all verified accounts have them? Your guess is as good as mine.

In addition to security measures, the other solution is to break up the tech monopolies. Companies like Facebook and Twitter have so much power because they are so large, and they face no real competition. This is a national-security risk as well as a personal-security risk. Were there 100 different Twitter-like companies, and enough compatibility so that all their feeds could merge into one interface, this attack wouldn’t have been such a big deal. More important, the risk of a similar but more politically targeted attack wouldn’t be so great. If there were competition, different platforms would offer different security options, as well as different posting rules, different authentication guidelines — different everything. Competition is how our economy works; it’s how we spur innovation. Monopolies have more power to do what they want in the quest for profits, even if it harms people along the way.

This wasn’t Twitter’s first security problem involving trusted insiders. In 2017, on his last day of work, an employee shut down President Donald Trump’s account. In 2019, two people were charged with spying for the Saudi government while they were Twitter employees.

Maybe this hack will serve as a wake-up call. But if past incidents involving Twitter and other companies are any indication, it won’t. Underspending on security, and letting society pay the eventual price, is far more profitable. I don’t blame the tech companies. Their corporate mandate is to make as much money as is legally possible. Fixing this requires changes in the law, not changes in the hearts of the company’s leaders.

This essay previously appeared on TheAtlantic.com.

EDITED TO ADD: This essay has been translated into Czech.

Posted on July 20, 2020 at 8:49 AMView Comments

Zoom Will Be End-to-End Encrypted for All Users

Zoom is doing the right thing: it’s making end-to-end encryption available to all users, paid and unpaid. (This is a change; I wrote about the initial decision here.)

…we have identified a path forward that balances the legitimate right of all users to privacy and the safety of users on our platform. This will enable us to offer E2EE as an advanced add-on feature for all of our users around the globe — free and paid — while maintaining the ability to prevent and fight abuse on our platform.

To make this possible, Free/Basic users seeking access to E2EE will participate in a one-time process that will prompt the user for additional pieces of information, such as verifying a phone number via a text message. Many leading companies perform similar steps on account creation to reduce the mass creation of abusive accounts. We are confident that by implementing risk-based authentication, in combination with our current mix of tools — including our Report a User function — we can continue to prevent and fight abuse.

Thank you, Zoom, for coming around to the right answer.

And thank you to everyone for commenting on this issue. We are learning — in so many areas — the power of continued public pressure to change corporate behavior.

EDITED TO ADD (6/18): Let’s do Apple next.

Posted on June 17, 2020 at 1:55 PMView Comments

Zoom's Commitment to User Security Depends on Whether you Pay It or Not

Zoom was doing so well…. And now we have this:

Corporate clients will get access to Zoom’s end-to-end encryption service now being developed, but Yuan said free users won’t enjoy that level of privacy, which makes it impossible for third parties to decipher communications.

“Free users for sure we don’t want to give that because we also want to work together with FBI, with local law enforcement in case some people use Zoom for a bad purpose,” Yuan said on the call.

This is just dumb. Imagine the scene in the terrorist/drug kingpin/money launderer hideout: “I’m sorry, boss. We could have have strong encryption to secure our bad intentions from the FBI, but we can’t afford the $20.” This decision will only affect protesters and dissidents and human rights workers and journalists.

Here’s advisor Alex Stamos doing damage control:

Nico, it’s incorrect to say that free calls won’t be encrypted and this turns out to be a really difficult balancing act between different kinds of harms. More details here:

Some facts on Zoom’s current plans for E2E encryption, which are complicated by the product requirements for an enterprise conferencing product and some legitimate safety issues. The E2E design is available here: https://github.com/zoom/zoom-e2e-whitepaper/blob/master/zoom_e2e.pdf

I read that document, and it doesn’t explain why end-to-end encryption is only available to paying customers. And note that Stamos said “encrypted” and not “end-to-end encrypted.” He knows the difference.

Anyway, people were rightly incensed by his remarks. And yesterday, Yuan tried to clarify:

Yuan sought to assuage users’ concerns Wednesday in his weekly webinar, saying the company was striving to “do the right thing” for vulnerable groups, including children and hate-crime victims, whose abuse is sometimes broadcast through Zoom’s platform.

“We plan to provide end-to-end encryption to users for whom we can verify identity, thereby limiting harm to vulnerable groups,” he said. “I wanted to clarify that Zoom does not monitor meeting content. We do not have backdoors where participants, including Zoom employees or law enforcement, can enter meetings without being visible to others. None of this will change.”

Notice that is specifically did not say that he was offering end-to-end encryption to users of the free platform. Only to “users we can verify identity,” which I’m guessing means users that give him a credit card number.

The Twitter feed was similarly sloppily evasive:

We are seeing some misunderstandings on Twitter today around our encryption. We want to provide these facts.

Zoom does not provide information to law enforcement except in circumstances such as child sexual abuse.

Zoom does not proactively monitor meeting content.

Zoom does no have backdoors where Zoom or others can enter meetings without being visible to participants.

AES 256 GCM encryption is turned on for all Zoom users — free and paid.

Those facts have nothing to do with any “misunderstanding.” That was about end-to-end encryption, which the statement very specifically left out of that last sentence. The corporate communications have been clear and consistent.

Come on, Zoom. You were doing so well. Of course you should offer premium features to paying customers, but please don’t include security and privacy in those premium features. They should be available to everyone.

And, hey, this is kind of a dumb time to side with the police over protesters.

I have emailed the CEO, and will report back if I hear back. But for now, assume that the free version of Zoom will not support end-to-end encryption.

EDITED TO ADD (6/4): Another article.

EDITED TO ADD (6/4): I understand that this is complicated, both technically and politically. (Note, though, Jitsi is doing it.) And, yes, lots of people confused end-to-end encryption with link encryption. (My readers tend to be more sophisticated than that.) My worry that the “we’ll offer end-to-end encryption only to paying customers we can verify, even though there’s plenty of evidence that ‘bad purpose’ people will just get paid accounts” story plays into the dangerous narrative that encryption itself is dangerous when widely available. And I disagree with the notion that the possibility of child exploitation is a valid reason to deny security to large groups of people.

Matthew Green on this issue. An excerpt:

Once the precedent is set that E2E encryption is too “dangerous” to hand to the masses, the genie is out of the bottle. And once corporate America accepts that private communications are too politically risky to deploy, it’s going to be hard to put it back.

From Signal:

Want to help us work on end-to-end encrypted group video calling functionality that will be free for everyone? Zoom on over to our careers page….

Posted on June 4, 2020 at 6:24 AMView Comments

Securing Internet Videoconferencing Apps: Zoom and Others

The NSA just published a survey of video conferencing apps. So did Mozilla.

Zoom is on the good list, with some caveats. The company has done a lot of work addressing previous security concerns. It still has a bit to go on end-to-end encryption. Matthew Green looked at this. Zoom does offer end-to-end encryption if 1) everyone is using a Zoom app, and not logging in to the meeting using a webpage, and 2) the meeting is not being recorded in the cloud. That’s pretty good, but the real worry is where the encryption keys are generated and stored. According to Citizen Lab, the company generates them.

The Zoom transport protocol adds Zoom’s own encryption scheme to RTP in an unusual way. By default, all participants’ audio and video in a Zoom meeting appears to be encrypted and decrypted with a single AES-128 key shared amongst the participants. The AES key appears to be generated and distributed to the meeting’s participants by Zoom servers. Zoom’s encryption and decryption use AES in ECB mode, which is well-understood to be a bad idea, because this mode of encryption preserves patterns in the input.

The algorithm part was just fixed:

AES 256-bit GCM encryption: Zoom is upgrading to the AES 256-bit GCM encryption standard, which offers increased protection of your meeting data in transit and resistance against tampering. This provides confidentiality and integrity assurances on your Zoom Meeting, Zoom Video Webinar, and Zoom Phone data. Zoom 5.0, which is slated for release within the week, supports GCM encryption, and this standard will take effect once all accounts are enabled with GCM. System-wide account enablement will take place on May 30.

There is nothing in Zoom’s latest announcement about key management. So: while the company has done a really good job improving the security and privacy of their platform, there seems to be just one step remaining to fully encrypt the sessions.

The other thing I want Zoom to do is to make the security options necessary to prevent Zoombombing to be made available to users of the free version of that platform. Forcing users to pay for security isn’t a viable option right now.

Finally — I use Zoom all the time. I finished my Harvard class using Zoom; it’s the university standard. I am having Inrupt company meetings on Zoom. I am having professional and personal conferences on Zoom. It’s what everyone has, and the features are really good.

Posted on April 30, 2020 at 10:24 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.