Schneier on Security

Mike the goat • October 18, 2013 11:03 AM

Personally I think the biggest risk has to be in letting each individual newspaper implement their own ‘strongbox’. No doubt these newspaper IT staff aren’t security nuts, and I can see this will end in tears.

If I was going to design this from the ground up I would do it as a cloud service, and here is how it would work:

• I would ask all participating papers to at least partially enable SSL. Even if they just had one load balancer push people over to the https site so you’ve got maybe a 1 in 10 chance of getting an SSLized connection. Allow people to force using SSL. The idea here is to ensure that there is enough legitimate SSL traffic so that our whistleblowers do not get spotted.
• We would give each newspaper a .tar.gz to extract onto their web server (their main domain otherwise we can’t hide these requests in with all the legit stuff), perhaps we make a new subdirectory called newstips/
• The ‘newstips’ section will have a page with some general opsec advice for people intending to leak and importantly some files to download. There will be a windows 32/64 universal .exe file, a MACOSX app, a PDF of how the implementation works and a .deb that has been statically linked to any obscure libraries so it hopefully works for ubuntu and debian users. There will also be a .tgz of the source code for review.
• In warzones and areas of civil unrest or civil disobedience rights groups can hand out a CD containing well – just a wget of that newstips/ directory. This is all a stranger needs to start leaking. We may have a script for the newspaper server admin to put in cron that changes the size of the file by adding fluff below the end of the file, etc.. so that traffic analysis is more difficult if the file is constantly changing size. We don’t intend for the newspaper site to be the primary place they go to download the files – but it’s one option for them. There will be many different ways to distribute, including just going to the cloud strongbox provider’s hidden service address with a web browser once you have tor. Or it can be mailed to you – again, all sorts of options.
• The downloaded Windows file is intended to be portable and to be put onto a fresh small USB stick. The user runs it off the stick (it doesn’t write a single byte to registry, etc.. it tries to keep solely to itself). The windows version of the program doesn’t go online until the actual time of submission either, which is good.
• So they run the app, select which mode to operate on (via tor or relay through a busy newspaper site using SSL – the latter is riskier but the only real option for those in oppressive regimes where using tor itself is criminal. Ideally you’d be in an internet cafe and use good opsec to ensure you’re not IDable). In the latter mode if there is too much info to upload and it is going to look unusually large going upstream versus all the other traffic it might suggest you do one part one day and another in a few days. The newspapers who run the relays can help (even though it is wasteful) by using some AJAX that makes clients using their site and reading the news push up some random junk).
• Once they’ve set their mode they then need to choose a passphrase. It will suggest a few (ala diceware style word lists) or they can enter Rtheir own. A brief dict run against 100,000 of the worst passwords is done when they click Next.
• The next step is key generation and the keypair is saved along with all the other settings that they are setting up in an AES256 encrypted container on the USB disk.
• Next they can drag all the files they want to leak into the drag and drop style interface. Going Next brings them to a display of all the hidden metadata that has been found and they can scrub the files if need be. It also gives them a lecture about covert metadata in the form of digital watermarking, steg, etc. There is a redaction tool and you can apply a range of filters to reduce the resolution and/or OCR a text only document and then reformat the text to avoid being caught out by document marking which uses font metrics and spacing. They can then use the redaction tool to securely redact. Finally the data they’ve chosen to leak is transcoded into an appropriate format and prepared.
• An address book is compiled into the binary. This shows all of the news agencies that use the service. They can select a news agency and then select a journalist. If the address book needs updating this can be done but you will be explicitly asked to confirm if you wish to go online (using whatever method you selected) to do this. Many will be preparing their docs at home and will want to defer this bit when they are on a public PC or wardriving. Anyway they can defer now and close the app or click next. Let’s assume next.
  At this point all of the queued data is archived into a single file and asymmetrically encrypted to the journalist’s public key (which is in the address book) and prepared ready to send.
• A summary of everything that is queued is shown. When you are ready you can click SUBMIT. It will go online (through tor if you accept the default) for strictly only long enough to do its bit and get the hell out.
• When successfully completed you will get a source codename. It is drawn from an English code book and is two words. This is used to uniquely identify the source should you wish to communicate in future. (ideally OTR style chat will be included at some point also). So, for example – “PATERNOSTER JOE”
• When you click FINISH it will inform you that it now wishes to securely erase your USB flash drive. It will also provide some handy hints on how to clean up the computer which you’ve handled the documents on, depending on the threat level. It will then securely erase the flash drive (as securely as you can erase flash that is) and recommend incineration.

IMHO that’s how I would handle such a thing.

Once on the cloud server for the strongbox-type service provider it will then be e-mailed to the journalist as a standard GPG encrypted email. Nothing fancy. Email can be split if need be.

By having a ‘service provider’ do all the hard stuff they can sit back and just let it work and let the experts look after the stuff that needs to be secure. IMHO. I have had a few too many glasses of wine tonight so I hope I am not too incoherent.