October 23, 2017

Archives for March 2016

Apple, FBI, and Software Transparency

The Apple versus FBI showdown has quickly become a crucial flashpoint of the “new Crypto War.” On February 16 the FBI invoked the All Writs Act of 1789, a catch-all authority for assistance of law enforcement, demanding that Apple create a custom version of its iOS to help the FBI decrypt an iPhone used by one of the San Bernardino shooters. The fact that the FBI allowed Apple to disclose the order publicly, on the same day, represents a rare exception to the government’s normal penchant for secrecy.

The reasons behind the FBI’s unusually loud entrance are important – but even more so is the risk that after the present flurry concludes, the FBI and other government agencies will revert to more shadowy methods of compelling companies to backdoor their software. This blog post explores these software transparency risks, and how new technical measures could help ensure that the public debate over software backdoors remains public.
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Apple/FBI: Freedom of speech vs. compulsion to sign

This week I signed the Electronic Frontier Foundation’s amicus (friend-of-the-court) brief in the Apple/FBI  iPhone-unlocking lawsuit.  Many prominent computer scientists and cryptographers signed: Josh Aas, Hal Abelson, Judy Anderson, Andrew Appel, Tom Ball (the Google one, not the Microsoft one), Boaz Barak, Brian Behlendorf, Rich Belgard, Dan Bernstein, Matt Bishop, Josh Bloch, Fred Brooks, Mark Davis, Jeff Dean, Peter Deutsch, David Dill, Les Earnest, Brendan Eich, David Farber, Joan Feigenbaum, Michael Fischer, Bryan Ford, Matt Franklin, Matt Green, Alex Halderman, Martin Hellman, Nadia Heninger, Miguel de Icaza, Tanja Lange, Ed Lazowska, George Ledin, Patrick McDaniel, David Patterson, Vern Paxson, Thomas Ristenpart, Ron Rivest, Phillip Rogaway, Greg Rose, Guido van Rossum, Tom Shrimpton, Barbara Simons, Gene Spafford, Dan Wallach, Nickolai Zeldovich, Yan Zhu, Phil Zimmerman. (See also the EFF’s blog post.)

The technical and legal argument is based on the First Amendment: (1) Computer programs are a form of speech; (2) the Government cannot compel you to “say” something any more than it can prohibit you from expressing something.  Also, (3) digital signatures are a form of signature; (4) the government cannot compel or coerce you to sign a statement that you don’t believe, a statement that is inconsistent with your values.  Each of these four statements has ample precedent in Federal law.  Combined together, (1) and (2) mean that Apple cannot be compelled to write a specific computer program.  (3) and (4) mean that even if the FBI wrote the program (instead of forcing Apple to write it), Apple could not be compelled to sign it with its secret signing key.  The brief argues,

By compelling Apple to write and then digitally sign new code, the Order forces Apple to first write a message to the government’s specifications, and then adopt, verify and endorse that message as its own, despite its strong disagreement with that message. The Court’s Order is thus akin to the government dictating a letter endorsing its preferred position and forcing Apple to transcribe it and sign its unique and forgery-proof name at the bottom.

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What Your ISP (Probably) Knows About You

Earlier this week, I came across a working paper from Professor Peter Swire—a highly respected attorney, professor, and policy expert.  Swire’s paper, entitled “Online Privacy and ISPs“, argues that ISPs have limited capability to monitor users’ online activity. The paper argues that ISPs have limited visibility into users’ online activity for three reasons:  (1) users are increasingly using many devices and connections, so any single ISP is the conduit of only a fraction of a typical user’s activity; (2) end-to-end encryption is becoming more pervasive, which limits ISPs’ ability to glean information about user activity; and (3) users are increasingly shifting to VPNs to send traffic.

An informed reader might surmise that this writeup relates to the reclassification of Internet service providers under Title II of the Telecommunications Act, which gives the FCC a mandate to protect private information that ISPs learn about their customers. This private information includes both personal information, as well as information about a customer’s use of the service that is provided as a result of receiving service—sometimes called Customer Proprietary Network Information, or CPNI. One possible conclusion a reader might draw from this white paper is that ISPs have limited capability to learn information about customers’ use of their service and hence should not be subject to additional privacy regulations.

I am not taking a position in this policy debate, nor do I intend to make any normative statements about whether an ISP’s ability to see this type of user information is inherently “good” or “bad” (in fact, one might even argue that an ISP’s ability to see this information might improve network security, network management, or other services). Nevertheless, these debates should be based on a technical picture that is as accurate as possible.  In this vein, it is worth examining Professor Swire’s “factual description of today’s online ecosystem” that claims to offer the reader an “up-to-date and accurate understanding of the facts”. It is true that the report certainly contains many facts, but it also omits important details about the “online ecosystem”. Below, I fill in what I see as some important missing pieces. Much of what I discuss below I have also sent verbatim in a letter to the FCC Chairman. I hope that the original report will ultimately incorporate some of these points.

[Update (March 9): Swire notes in a response that the report itself doesn’t contain technical inaccuracies. Although there are certainly many points that are arguable, they are hard to disprove without better data, so it is difficult to “prove” the inaccuracies. Even if we take it as a given that there are no inaccuracies, that’s a very different thing than saying that the report tells the whole story.]
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