Entries Tagged "cell phones"

Page 17 of 29

Circumventing Communications Blackouts

Rangzen looks like a really interesting ad hoc mesh networking system to circumvent government-imposed communications blackouts. I am particularly interested in how it uses reputation to determine who can be trusted, while maintaining some level of anonymity.

Academic paper:

Abstract: A challenging problem in dissent networking is that of circumventing large-scale communication blackouts imposed by oppressive governments. Although prior work has not focused on the need for user anonymity, we contend that it is essential. Without anonymity, governments can use communication networks to track and persecute users. A key challenge for decentralized networks is that of resource allocation and control. Network resources must be shared in a manner that deprioritizes unwanted traffic and abusive users. This task is typically addressed through reputation systems that conflict with anonymity. Our work addresses this paradox: We prioritize resources in a privacy-preserving manner to create an attack-resilient, anonymity-preserving, mobile ad-hoc network. Our prioritization mechanism exploits the properties of a social trust graph to promote messages relayed via trusted nodes. We present Rangzen, a microblogging solution that uses smartphones to opportunistically relay messages among citizens in a delay-tolerant network (DTN) that is independent of government or corporate-controlled infrastructure.

This is exactly the sort of thing I was thinking about in this essay.

Posted on August 14, 2013 at 7:43 AM • View Comments

Twitter's Two-Factor Authentication System

Twitter just rolled out a pretty nice two-factor authentication system using your smart phone as the second factor:

The new two-factor system works like this. A user enrolls using the mobile app, which generates a 2048-bit RSA keypair. The private key lives on the phone itself, and the public key is uploaded to Twitter’s server.

When Twitter receives a new login request with a username and password, the server sends a challenge based on a 190-bit, 32 character random nonce, to the mobile app—along with a notification that gives the user the time, location, and browser information associated with the login request. The user can then opt to approve or deny this login request. If approved, the app replies to a challenge with its private key, relays that information back to the server. The server compares that challenge with a request ID, and if it authenticates, the user is automatically logged in.

On the user end, this means there’s no string of numbers to enter, nor do you have to swap to a third party authentication app or carrier. You just use the Twitter client itself. It means that the system isn’t vulnerable to a compromised SMS delivery channel, and moreover, it’s easy.

Posted on August 8, 2013 at 12:20 PM • View Comments

How Apple Continues to Make Security Invisible

Interesting article:

Apple is famously focused on design and human experience as their top guiding principles. When it comes to security, that focus created a conundrum. Security is all about placing obstacles in the way of attackers, but (despite the claims of security vendors) those same obstacles can get in the way of users, too.

[…]

For many years, Apple tended to choose good user experience at the expense of leaving users vulnerable to security risks. That strategy worked for a long time, in part because Apple’s comparatively low market share made its products less attractive targets. But as Apple products began to gain in popularity, many of us in the security business wondered how Apple would adjust its security strategies to its new position in the spotlight.

As it turns out, the company not only handled that change smoothly, it has embraced it. Despite a rocky start, Apple now applies its impressive design sensibilities to security, playing the game its own way and in the process changing our expectations for security and technology.

EDITED TO ADD (7/11): iOS security white paper.

Posted on July 5, 2013 at 1:33 PM • View Comments

Preventing Cell Phone Theft through Benefit Denial

Adding a remote kill switch to cell phones would deter theft.

Here we can see how the rise of the surveillance state permeates everything about computer security. On the face of it, this is a good idea. Assuming it works—that 1) it’s not possible for thieves to resurrect phones in order to resell them, and 2) that it’s not possible to turn this system into a denial-of-service attack tool—it would deter crime. The general category of security is “benefit denial,” like ink tags attached to garments in retail stores and car radios that no longer function if removed. But given what we now know, do we trust that the government wouldn’t abuse this system and kill phones for other reasons? Do we trust that media companies won’t kill phones it decided were sharing copyrighted materials? Do we trust that phone companies won’t kill phones from delinquent customers? What might have been a straightforward security system becomes a dangerous tool of control, when you don’t trust those in power.

Posted on June 28, 2013 at 1:37 PM • View Comments

New Details on Skype Eavesdropping

This article, on the cozy relationship between the commercial personal-data industry and the intelligence industry, has new information on the security of Skype.

Skype, the Internet-based calling service, began its own secret program, Project Chess, to explore the legal and technical issues in making Skype calls readily available to intelligence agencies and law enforcement officials, according to people briefed on the program who asked not to be named to avoid trouble with the intelligence agencies.

Project Chess, which has never been previously disclosed, was small, limited to fewer than a dozen people inside Skype, and was developed as the company had sometimes contentious talks with the government over legal issues, said one of the people briefed on the project. The project began about five years ago, before most of the company was sold by its parent, eBay, to outside investors in 2009. Microsoft acquired Skype in an $8.5 billion deal that was completed in October 2011.

A Skype executive denied last year in a blog post that recent changes in the way Skype operated were made at the behest of Microsoft to make snooping easier for law enforcement. It appears, however, that Skype figured out how to cooperate with the intelligence community before Microsoft took over the company, according to documents leaked by Edward J. Snowden, a former contractor for the N.S.A. One of the documents about the Prism program made public by Mr. Snowden says Skype joined Prism on Feb. 6, 2011.

Reread that Skype denial from last July, knowing that at the time the company knew that they were giving the NSA access to customer communications. Notice how it is precisely worded to be technically accurate, yet leave the reader with the wrong conclusion. This is where we are with all the tech companies right now; we can’t trust their denials, just as we can’t trust the NSA—or the FBI—when it denies programs, capabilities, or practices.

Back in January, we wondered whom Skype lets spy on their users. Now we know.

Posted on June 20, 2013 at 2:42 PM • View Comments

Bluetooth-Controlled Door Lock

Here is a new lock that you can control via Bluetooth and an iPhone app.

That’s pretty cool, and I can imagine all sorts of reasons to get one of those. But I’m sure there are all sorts of unforeseen security vulnerabilities in this system. And even worse, a single vulnerability can affect all the locks. Remember that vulnerability found last year in hotel electronic locks?

Anyone care to guess how long before some researcher finds a way to hack this one? And how well the maker anticipated the need to update the firmware to fix the vulnerability once someone finds it?

I’m not saying that you shouldn’t use this lock, only that you understand that new technology brings new security risks, and electronic technology brings new kinds of security risks. Security is a trade-off, and the trade-off is particularly stark in this case.

Posted on May 16, 2013 at 8:45 AM • View Comments

Remotely Hijacking an Aircraft

There is a lot of buzz on the Internet about a talk at the Hack-in-the Box conference by Hugo Teso, who claims he can hack in to remotely control an airplane’s avionics. He even wrote an Android app to do it.

I honestly can’t tell how real this is, and how much of it is the unique configuration of simulators he tested this on. On the one hand, it can’t possibly be true that an aircraft avionics computer accepts outside commands. On the other hand, we’ve seen lots of security vulnerabilities that seem impossible to be true. Right now, I’m skeptical.

EDITED TO ADD (4/12): Three good refutations.

Posted on April 12, 2013 at 10:50 AM • View Comments

Apple's iMessage Encryption Seems to Be Pretty Good

The U.S. Drug Enforcement Agency has complained (in a classified report, not publicly) that Apple’s iMessage end-to-end encryption scheme can’t be broken. On the one hand, I’m not surprised; end-to-end encryption of a messaging system is a fairly easy cryptographic problem, and it should be unbreakable. On the other hand, it’s nice to have some confirmation that Apple is looking out for the users’ best interests and not the governments’.

Still, it’s impossible for us to know if iMessage encryption is actually secure. It’s certainly possible that Apple messed up somewhere, and since we have no idea how their encryption actually works, we can’t verify its functionality. It would be really nice if Apple would release the specifications of iMessage security.

EDITED TO ADD (4/8): There’s more to this story:

The DEA memo simply observes that, because iMessages are encrypted and sent via the Internet through Apple’s servers, a conventional wiretap installed at the cellular carrier’s facility isn’t going to catch those iMessages along with conventional text messages. Which shouldn’t exactly be surprising: A search of your postal mail isn’t going to capture your phone calls either; they’re just different communications channels. But the CNET article strongly implies that this means encrypted iMessages cannot be accessed by law enforcement at all. That is almost certainly false.

The question is whether iMessage uses true end-to-end encryption, or whether Apple has copies of the keys.

Another article.

Posted on April 5, 2013 at 1:05 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.