|Highlights of DEFCON 22|
The twenty-second DEFCON took over Las Vegas last week, and brought many interesting and notable speakers. I took a few notes from the talks that stood out to me, and I'm passing them along here.
Paul Vixie, Internet pioneer and DNS expert. Vixie spoke about his DNSDB project for accumulating global DNS resource records in a passive fashion, and making this information available to researchers and security product vendors. He also spoke about his DNS firewall for shielding users from malicious throwaway domain names.
Phil Zimmerman, creator of PGP and president of Silent Circle. Zimmerman spoke about wiretap overcompliance in the telecommunications industry, trust in cryptographic techniques, and his new endeavors at Silent Circle. Reading about Zimmerman's PGP efforts and the resulting drama (PGP: Pretty Good Privacy, Simson Garfinkel) is what got me interested in cryptography many years ago, so it was great to see a living legend on the stage. I did take issues with a few of his comments, though. When asked about trusting binary executables, Zimmerman mentioned the problem of distributing a binary which is identical to one that might be produced from source, due to differences in timestamps — and failed to discuss recent progress in reproducible build techniques which are meant to solve that problem. He also painted a somewhat rosy picture of the legislative attitude towards cryptography and privacy: we won the Crypto Wars in the 1990's, and cryptographic freedom can't be rolled back again now that everyone relies on it. This does not seem to be the case — last year, Congress and the administration was pushing a proposal which would effectively outlaw peer-to-peer communication systems that might be problematic to wiretap. (Thankfully, the Snowden revelations made the proposal politically toxic for now, and it has been shelved.)
Kenneth White, security researcher. White spoke about the Open Crypto Audit project which he launched along with cryptographer Matthew Green, and the drama caused by their first audit subject, TrueCrypt, being suddenly discontinued under mysterious circumstances. I've followed the progress of the Open Crypto Audit project and the ongoing news about the TrueCrypt disappearance, so there wasn't much in the talk that was new to me. It was interesting to hear that some of the biggest challenges of Open Crypt Audit were the community aspects of audit fundraising. White reported that they will finish the TrueCrypt audit in spite of the shutdown, and then move on to OpenSSL.
Dan Kaminsky, security researcher. Kaminsky scored a coveted two-hour slot in the Penn and Teller theater, which he fully used to discuss a variety of topics:
- Secure random by default. Kaminsky argued that most vulnerabilities resulting from random number generation are not due to exotic attacks on complex algorithms, but rather gross missteps in the use and generation of randomness. For instance, some software has been observed to only effectively use 32 bits of entropy, while others employ the use of linear feedback shift registers (LFSRs) in spite of their easy cryptanalysis. Kaminsky proposes a new Liburandy library which wraps /dev/urandom when appropriate.
- Storybits. Kaminsky invited Ryan Castellucci onto the stage to demonstrate Storybits 0.1, a new cryptomnemonic scheme for people to remember binary strings such as keys, fingerprints, secrets, etc. The system encodes the data as adjective-noun-verb tuples to make the data easier to remember, and provide error correction by way of spellcheck auto-correct.
- Memory hardening. Convinced that improper memory usage is a major cause of vulnerabilities, Kaminsky outlined several strategies for memory-hardening applications. These include use of a typed heap (as Google does in Chrome), the use of nondeterministic freeing (as Microsoft does in Internet Explorer), and a novel approach called IronHeap where 64-bit virtual memory addresses are simply never freed (although pages may be returned for MMU reuse). He also announced the formation of a team to memory-harden Firefox, to provide added security for the Tor Browser Bundle.
- Distributed Denial of Service (DDoS) mitigation. Kaminsky considers the rise of DDoS attacks using techniques such as datagram amplification to be an existential threat to the Internet. He proposes a new scheme of sending tracer packets within data flows to indicate when source address spoofing may be happening.
- NSA. Kaminsky is concerned that the NSA backlash may lead to a balkanization of the Internet, as various nations opt to develop their own internal systems for core Internet services.
- Apple bug bounties. Finally, Kaminsky is quite happy that Apple is offering bug bounties relating to Safari autoredirection.
Kaminsky's slides are available.
Ladar Levison, founder of Lavabit. Levison spoke about his proposed Dark Mail Alliance, a new electronic mail system designed to preserve the privacy of users. He began by announcing a new name for the project: DIME, the Dark Internet Mail Environment. I was a bit disappointed in the new name — "Dark" can have a sinister connotation for some people, and privacy preserving technologies should be marketed to the public with positive names reflecting the true value they provide. He should have renamed the project TIME, the Trustworthy Internet Mail Environment. Levison outlined the basic components of the system, including a server called Magma and a modified Thunderbird client called Volcano. DIME unfortunately does not provide forward secrecy for messages, although Levison pointed out that there was forward secrecy at the TLS1.2 line level. There was also talk of a pseudo-onion scheme to shield metadata and provide some small measure of anonymity, but it wasn't clear to me how this was implemented.
Adam Caudill, software developer and security researcher. In DEFCON's new Crypto Village, Caudill proposed a new secure electronic mail system called Simple Messaging and Identity Management Protocol (SMIMP). This scheme shares some of the same goals as Levison's DIME, but provides an alternative design intended to be developed in the open among the greater Internet engineering community. The most interesting thing to me was a Hashcash-like proof-of-work requirement for reducing spam.