Sep 28, 2020

I was giving a talk at DefCon one year and this guy starts grilling me at the end of the talk about the techniques Apple was using to encrypt home directories at the time with new technology called Filevault. It went on a bit, so I did that thing you sometimes have to do when it’s time to get off stage and told him we’d chat after. And of course he came up - and I realized he was really getting at the mechanism used to decrypt and the black box around decryption. He knew way more than I did about encryption so I asked him who he was. When he told me, I was stunned.

Turns out that like me, he enjoyed listening to A Prairie Home Companion. And on that show, Garrison Keillor would occasionally talk about Ralph’s Pretty Good Grocery in a typical Minnesota hometown he’d made up for himself called Lake Wobegon. Zimmerman liked the name and so called his new encryption tool PGP, short for Pretty Good Privacy. It was originally written to encrypt messages being sent to bulletin boards. 

That original tool didn’t require any special license, provided it wasn’t being used commercially. And today, much to the chagrin of the US government at the time, it’s been used all over the world to encrypt emails, text files, text messages, directories, and even disks. But we’ll get to that in a bit. 

Zimmerman had worked for the Nuclear Weapons Freeze Campaign in the 80s after getting a degree in computer science fro Florida Atlantic University in 1978. And after seeing the government infiltrate organizations organizing Vietnam protests, he wanted to protect the increasingly electronic communications of anti-nuclear protests and activities. 

The world was just beginning to wake up to a globally connected Internet. And the ARPAnet had originally been established by the military industrial complex, so it was understandable that he’d want to keep messages private that just happened to be flowing over a communications medium that many in the defense industry knew well. So he started developing his own encryption algorithm called BassOmatic in 1988. That cipher used symmetric keys with control bits and pseudorandom number generation as a seed - resulting in 8 permutation tables. He named BassOmatic after a Saturday Night Live skit. I like him more and more. 

He’d replace BassOmatic with IDEA in version 2 in 1992. And thus began the web of trust, which survives to this day in PGP, OpenPGP, and GnuPG. Here, a message is considered authentic based on it being bound to a public key - one that is issued in a decentralized model where a certificate authority issues a public and private key where messages can only be encrypted or signed with the private key and back then you would show your ID to someone at a key signing event or party in order to get a key. Public keys could then be used to check that the individual you thought was the signer really is. Once verified then a separate key could be used to encrypt messages between the parties. 

But by then, there was a problem. The US government began a criminal investigation against Zimmerman in 1993. You see, the encryption used in PGP was too good. Anything over a 40 bit encryption key was subject to US export regulations as a munition. Remember, the Cold War. Because PGP used 128 bit keys at a minimum. So Zimmerman did something that the government wasn’t expecting. Something that would make him a legend. He went to MIT Press and published the PGP source code in a physical book. Now, you could OCR the software, run it through a compiler. Suddenly, his code was protected as an exportable book by the First Amendment. 

The government dropped the investigation and found something better to do with their time. And from then on, source code for cryptographic software became an enabler of free speech, which has been held up repeatedly in the appellate courts. So 1996 comes along and PGP 3 is finally available. This is when Zimmerman founds PGP as a company so they could focus on PGP full-time. Due to a merger with Viacrypt they jumped to PGP 5 in 1997. 

Towards the end of 1997 Network Associates acquired PGP and they expanded to add things like intrusion detection, full disk encryption, and even firewalls. Under Network Associates they stopped publishing their source code and Zimmerman left in 2001. Network Associates couldn’t really find the right paradigm and so merged some products together and what was PGP commandline ended up becoming McAfee E-Business Server in 2013. 

But by 2002 PGP Corporation was born out of a few employees securing funding from Rob Theis to help start the company and buy the rest of the PGP assets from Network Associates. They managed to grow it enough to sell it for $300 million to Symantec and PGP lives on to this day. 

But I never felt like they were in it just for the money. The money came from a centralized policy server that could do things like escrow keys. But for that core feature of encrypting emails and later disks, I really always felt like they wanted a lot of that free. And you can buy Symantec Encryption Desktop and command it from a server, S/MIME and OpenPGP live on in ways that real humans can encrypt their communications, some of which in areas where their messages might get them thrown in jail.

By the mid-90s, mail wasn’t just about the text in a message. It was more. RFC934 in 1985 had started the idea of encapsulating messages so you could get metadata. RFC 1521 in 1993 formalized MIME and by 1996, MIME was getting really mature in RFC2045. But by 1999 we wanted more and so S/MIME went out as RFC 2633. Here, we could use CMS to “cryptographically enhance” a MIME body. In other words, we could suddenly encrypt more than the text of an email and it since it was an accepted internet standard, it could be encrypted and decrypted with standard mail clients rather than just with a PGP client that didn’t have all the bells and whistles of pretty email clients. 

That included signing information, which by 2004 would evolve to include attributes for things like singingTime, SMIMECapabilities, algorithms and more. 

Today, iOS can use S/MIME and keys can be stored in Exchange or Office 365 and that’s compatible with any other mail client that has S/MIME support, making it easier than ever to get certificates, sign messages, and encrypt messages. Much of what PGP was meant for is also available in OpenPGP. OpenPGP is defined by the OpenPGP Working Group and you can see the names of some of these guardians of privacy in RFC 4880 from 2007. Names like J. Callas, L. Donnerhacke, H. Finney, D. Shaw, and R. Thayer. Despite the corporate acquisitions, the money, the reprioritization of projects, these people saw fit to put powerful encryption into the hands of real humans and once that pandoras box had been opened and the first amendment was protecting that encryption as free speech, to keep it that way. Use Apple Mail, GPGTools puts all of this in your hands. Use Android, get FairEmail. Use Windows, grab EverDesk. 

This specific entry felt a little timely. Occasionally I hear senators tell companies they need to leave backdoors in products so the government can decrypt messages. And a terrorist forces us to rethink that basic idea of whether software that enables encryption is protected by freedom of speech. Or we choose to attempt to ban a company like WeChat, testing whether foreign entities who publish encryption software are also protected. Especially when you consider whether Tencent is harvesting user data or if the idea they are doing that is propaganda. For now, US courts have halted a ban on WeChat. Whether it lasts is one of the more intriguing things I’m personally watching these days, despite whatever partisan rhetoric gets spewed from either side of the isle, simply for the refinement to the legal interpretation that to me began back in 1993. After over 25 years we still continue to evolve our understanding of what truly open and peer reviewed cryptography being in the hands of all of us actually means to society. 

The inspiration for this episode was a debate I got into about whether the framers of the US Constitution would have considered encryption, especially in the form of open source public and private key encryption, to be free speech. And it’s worth mentioning that Washington, Franklin, Hamilton, Adams, and Madison all used  ciphers to keep their communications private. And for good reason as they knew what could happen should their communications be leaked, given that Franklin had actually leaked private communications when he was the postmaster general. Jefferson even developed his own wheel cipher, which was similar to the one the US army used in 1922. It comes down to privacy. The Constitution does not specifically call out privacy; however, the first Amendment guarantees the privacy of belief, the third, the privacy of home, the fourth, privacy against unreasonable search and the fifth, privacy of of personal information in the form of the privilege against self-incrimination. And giving away a private key is potentially self-incrimination. Further, the ninth Amendment has broadly been defined as the protection of privacy. 

So yes, it is safe to assume they would have supported the transmission of encrypted information and therefore the cipher used to encrypt to be a freedom. Arguably the contents of our phones are synonymous with the contents of our homes though - and if you can have a warrant for one, you could have a warrant for both. Difference is you have to physically come to my home to search it - whereas a foreign government with the same keys might be able to decrypt other data. Potentially without someone knowing what happened. The Electronic Communications Privacy Act of 1986 helped with protections but with more and more data residing in the cloud - or as with our mobile devices synchronized with the cloud, and with the intermingling of potentially harmful data about people around the globe potentially residing (or potentially being analyzed) by people in countries that might not share the same ethics, it’s becoming increasingly difficult to know what is the difference between keeping our information private, which the framers would likely have supported and keeping people safe. Jurisprudence has never kept up with the speed of technological progress, but I’m pretty sure that Jefferson would have liked to have shared a glass of his favorite drink, wine, with Zimmerman. Just as I’m pretty sure I’d like to share a glass of wine with either of them. At Defcon or elsewhere!