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Thursday, September 5, 2013

Bruce Schneier:How to remain secure against NSA surveillance

Computer security expert Bruce Schneier has written two excellent articles for the Guardian today about NSA surveillance and how it works, each of which should be read in its entirety:

The NSA has undermined a fundamental social contract. We engineers built the internet – and now we have to fix it.

The NSA has huge capabilities – and if it wants in to your computer, it's in. With that in mind, here are five ways to stay safe.

Here are the 5 tips (but read the whole article!):

With all this in mind, I have five pieces of advice:

1) Hide in the network. Implement hidden services. Use Tor to anonymize yourself. Yes, the NSA targets Tor users, but it's work for them. The less obvious you are, the safer you are.

2) Encrypt your communications. Use TLS. Use IPsec. Again, while it's true that the NSA targets encrypted connections – and it may have explicit exploits against these protocols – you're much better protected than if you communicate in the clear.

3) Assume that while your computer can be compromised, it would take work and risk on the part of the NSA – so it probably isn't. If you have something really important, use an air gap. Since I started working with the Snowden documents, I bought a new computer that has never been connected to the internet. If I want to transfer a file, I encrypt the file on the secure computer and walk it over to my internet computer, using a USB stick. To decrypt something, I reverse the process. This might not be bulletproof, but it's pretty good.

4) Be suspicious of commercial encryption software, especially from large vendors. My guess is that most encryption products from large US companies have NSA-friendly back doors, and many foreign ones probably do as well. It's prudent to assume that foreign products also have foreign-installed backdoors. Closed-source software is easier for the NSA to backdoor than open-source software. Systems relying on master secrets are vulnerable to the NSA, through either legal or more clandestine means.

5) Try to use public-domain encryption that has to be compatible with other implementations. For example, it's harder for the NSA to backdoor TLS than BitLocker, because any vendor's TLS has to be compatible with every other vendor's TLS, while BitLocker only has to be compatible with itself, giving the NSA a lot more freedom to make changes. And because BitLocker is proprietary, it's far less likely those changes will be discovered. Prefer symmetric cryptography over public-key cryptography. Prefer conventional discrete-log-based systems over elliptic-curve systems; the latter have constants that the NSA influences when they can.

Since I started working with Snowden's documents, I have been usingGPG, Silent Circle, Tails, OTR, TrueCrypt, BleachBit, and a few other things I'm not going to write about. There's an undocumented encryption feature in my Password Safe program from the command line); I've been using that as well.

I understand that most of this is impossible for the typical internet user. Even I don't use all these tools for most everything I am working on. And I'm still primarily on Windows, unfortunately. Linux would be safer.

The NSA has turned the fabric of the internet into a vast surveillance platform, but they are not magical. They're limited by the same economic realities as the rest of us, and our best defense is to make surveillance of us as expensive as possible.

Trust the math. Encryption is your friend. Use it well, and do your best to ensure that nothing can compromise it. That's how you can remain secure even in the face of the NSA.

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