LeakSourceNews
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How Laura Poitras Helped Snowden Spill His Secrets
Olaf Blecker for The New York Times
Documentary filmmaker Laura Poitras in Berlin.
By PETER MAASS
Published: August 13, 2013
This
past January, Laura Poitras received a curious e-mail from an anonymous
stranger requesting her public encryption key. For almost two years,
Poitras had been working on a documentary about surveillance, and she
occasionally received queries from strangers. She replied to this one
and sent her public key — allowing him or her to send an encrypted
e-mail that only Poitras could open, with her private key — but she
didn’t think much would come of it.
Why he turned to Poitras and Greenwald.
The
stranger responded with instructions for creating an even more secure
system to protect their exchanges. Promising sensitive information, the
stranger told Poitras to select long pass phrases that could withstand a
brute-force attack by networked computers. “Assume that your adversary
is capable of a trillion guesses per second,” the stranger wrote.
Before
long, Poitras received an encrypted message that outlined a number of
secret surveillance programs run by the government. She had heard of one
of them but not the others. After describing each program, the stranger
wrote some version of the phrase, “This I can prove.”
Seconds
after she decrypted and read the e-mail, Poitras disconnected from the
Internet and removed the message from her computer. “I thought, O.K., if
this is true, my life just changed,” she told me last month. “It was
staggering, what he claimed to know and be able to provide. I just knew
that I had to change everything.”
Poitras remained wary of whoever
it was she was communicating with. She worried especially that a
government agent might be trying to trick her into disclosing
information about the people she interviewed for her documentary,
including Julian Assange, the editor of WikiLeaks. “I called him out,”
Poitras recalled. “I said either you have this information and you are
taking huge risks or you are trying to entrap me and the people I know,
or you’re crazy.”
The answers were reassuring but not definitive.
Poitras did not know the stranger’s name, sex, age or employer (C.I.A.?
N.S.A.? Pentagon?). In early June, she finally got the answers. Along
with her reporting partner, Glenn Greenwald, a former lawyer and a
columnist for The Guardian, Poitras flew to Hong Kong and met the N.S.A.
contractor Edward J. Snowden, who gave them thousands of classified
documents, setting off a major controversy over the extent and legality
of government surveillance. Poitras was right that, among other things,
her life would never be the same.
Greenwald lives and
works in a house surrounded by tropical foliage in a remote area of Rio
de Janeiro. He shares the home with his Brazilian partner and their 10
dogs and one cat, and the place has the feel of a low-key fraternity
that has been dropped down in the jungle. The kitchen clock is off by
hours, but no one notices; dishes tend to pile up in the sink; the
living room contains a table and a couch and a large TV, an Xbox console
and a box of poker chips and not much else. The refrigerator is not
always filled with fresh vegetables. A family of monkeys occasionally
raids the banana trees in the backyard and engages in shrieking battles
with the dogs.
Mauricio Lima for The New York Times
Glenn Greenwald, a writer for The Guardian, at home in Rio de Janeiro.
Greenwald
does most of his work on a shaded porch, usually dressed in a T-shirt,
surfer shorts and flip-flops. Over the four days I spent there, he was
in perpetual motion, speaking on the phone in Portuguese and English,
rushing out the door to be interviewed in the city below, answering
calls and e-mails from people seeking information about Snowden,
tweeting to his 225,000 followers (and conducting intense arguments with
a number of them), then sitting down to write more N.S.A. articles for
The Guardian, all while pleading with his dogs to stay quiet. During one
especially fever-pitched moment, he hollered, “Shut up, everyone,” but
they didn’t seem to care.
Amid the chaos, Poitras, an
intense-looking woman of 49, sat in a spare bedroom or at the table in
the living room, working in concentrated silence in front of her
multiple computers. Once in a while she would walk over to the porch to
talk with Greenwald about the article he was working on, or he would
sometimes stop what he was doing to look at the latest version of a new
video she was editing about Snowden. They would talk intensely —
Greenwald far louder and more rapid-fire than Poitras — and occasionally
break out laughing at some shared joke or absurd memory. The Snowden
story, they both said, was a battle they were waging together, a fight
against powers of surveillance that they both believe are a threat to
fundamental American liberties.
Read More Here
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Snowden: American media 'abdicated their role as check to power'
Published time: August 14, 2013 14:13
Edited time: August 15, 2013 04:55
(L-R)
Laura Poitras (Reuters / Lucy Nicholson), Edward Snowden (AFP Photo /
The Guardian) and Glenn Greenwald (Reuters / Sergio Moraes)
NSA
whistleblower Edward Snowden has gone on the offensive against his
critics in the US, accusing the mainstream media there of failing their
audiences “for fear of being seen as unpatriotic and punished in the
market.”
In a rare interview, Snowden explained why he chose a UK journalist and a documentary filmmaker for his leaks.
In
an encrypted e-mail correspondence with journalist Peter Maass, the
former NSA contractor-turned-whistleblower presented his candid opinion
of the US media and what finally persuaded him to go public on the NSA’s
worldwide surveillance program.
The heightened level of
nationalism prevalent in the United States following the attacks of 9/11
precluded US media from engaging in any serious discussion on the
excesses of government behavior for fear of seeming
“unpatriotic,” Snowden argued in the interview published in The New York Times – his first since gaining temporary asylum in Russia.
“After
9/11, many of the most important news outlets in America abdicated
their role as a check to power — the journalistic responsibility to
challenge the excesses of government — for fear of being seen as
unpatriotic and punished in the market during a period of heightened
nationalism,” the NY Times reported Snowden as saying.
The former CIA employee said this strategy by the American media establishment had
“ended up costing the public dearly.”
Snowden
then revealed what led him to divulge his explosive information to
Laura Poitras, the documentary filmmaker who served first as an
intermediary between Snowden and Glenn Greenwald, an investigative
journalist with The Guardian, and now with Maass.
“Laura and
Glenn are among the few who reported fearlessly on controversial topics
throughout this period, even in the face of withering personal
criticism, and resulted in Laura specifically becoming targeted by the
very programs involved in the recent disclosures,” Snowden said.
Poitras
“demonstrated
the courage, personal experience and skill needed to handle what is
probably the most dangerous assignment any journalist can be given —
reporting on the secret misdeeds of the most powerful government in the
world,” Snowden said in the NY Times interview, adding that those qualifications made her
“an obvious choice.”
Demonstrators
hold up a placard in support of former US agent of the National
Security Agency, Edward Snowden in front of Berlin's landmark
Brandenburg Gate (AFP Photo / John Macdougall)
The interview
then focused on what made Snowden, who arrived on May 20 in Hong Kong
with details of the NSA’s PRISM program, confident that he could place
his trust in Poitras.
Snowden told Maass that he discovered Poitras was
“more suspicious of me than I was of her, and I’m famously paranoid.”
Read More Here
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Encryption Works: How to Protect Your Privacy in the Age of NSA Surveillance
View this whitepaper in PDF form.
Encryption
works. Properly implemented strong crypto systems are one of the few
things that you can rely on. Unfortunately, endpoint security is so
terrifically weak that NSA can frequently find ways around it.
The
NSA is the biggest, best funded spy agency the world has ever seen.
They spend billions upon billions of dollars each year doing everything
they can to vacuum up the digital communications of most humans on this
planet that have access to the Internet and and the phone network. And
as the recent reports in the Guardian and Washington Post show, even
domestic American communications are not safe from their net.
Defending
yourself against the NSA, or any other government intelligence agency,
is not simple, and it's not something that can be solved just by
downloading an app. But thanks to the dedicated work of civilian
cryptographers and the free and open source software community, it's
still possible to have privacy on the Internet, and the software to do
it is freely available to everyone. This is especially important for
journalists communicating with sources online.
Table of Contents
Threat Model
The
NSA is a powerful adversary. If you are its direct target, you have to
go to great lengths to communicate in private, and even if you're not,
billions of innocent Internet users get caught in the NSA's dragnet too.
While
the tools and advice in this paper are aimed at protecting your privacy
from the NSA's collection methods, the same advice can be used to
increase your computer security against any adversary. It's important to
remember that other governments, including China and Russia, spend
massive amounts of money of their own high-tech surveillance equipment
and are known to specifically target journalists and sources. In the US,
bad digital security can cost whistleblowers their freedom, but in
other countries it can cost both journalists and sources their lives. A
recent example from Syria illustrates how careless digital security can have tragic results.
But
changing some basic software practices could award you a great deal of
privacy, even if it doesn't keep you secure against targeted attacks by
governments. This paper explores methods you can use in both cases.
Crypto Systems
We
discovered something. Our one hope against total domination. A hope
that with courage, insight and solidarity we could use to resist. A
strange property of the physical universe that we live in.
The universe believes in encryption.
It is easier to encrypt information than it is to decrypt it.
— Julian Assange, in the introduction of Cypherpunks: Freedom and the Future of the Internet
Encryption
is the process of taking a plaintext message and a randomly generated
key and doing mathematical operations with the two until all that's left
is a scrambled, ciphertext version of the message. Decryption is taking
the ciphertext and the right key and doing more mathematical operations
until the plaintext is recovered. This field is called cryptography, or
crypto for short. A crypto algorithm, what mathematical operations to
do and how to do them, is called a cipher.
To encrypt something
you need the right key, and you need the right key to decrypt it too. If
the crypto software is implemented properly, if the math is sound, and
if the keys are secure, all of the combined computing power on Earth
cannot break this encryption.
We build crypto systems that depend
on problems in mathematics that we believe to be hard, such as the
difficulty in factoring large numbers. Unless there are mathematical
breakthroughs that make these problems easier—and the NSA is keeping
them secret from the rest of the world—breaking crypto that relies on
them for security is unfeasible.
The design of crypto systems and
ciphers should be completely public. The only way to ensure that the
cipher itself doesn't have a critical flaw is to publish how it works,
to have many eyes scrutinizing it in detail, and to let it weather
real-world attacks in the wild to work out the bugs. The inner workings
of most crypto that we use on a daily basis, like
HTTPS,
the technology that makes it possible to safely type credit card
numbers and passwords into website forms, is completely public. An
attacker that knows every single detail about how the encryption works
should still fail to break the encryption without possessing the key.
Crypto that is proprietary, and its underlying code secret, cannot be
trusted to be secure.
Here's an important question to ask when
assessing if a service or app that uses encryption is secure: Is it
possible for the service provider itself to circumvent the encryption?
If so, you cannot trust the security of the service. Many services like
Skype and
Hushmail
promise "end-to-end" encryption, but often times it still means that
the services themselves have the keys to decrypt the product. True
end-to-end encryption means that the service provider cannot look at
your communications even if they wanted to.
Another important fact
to know about encryption is that it's about much more than protecting
the privacy of communications. It can be used to "digitally sign"
messages in a way that proves that the message originated from the
person you expected it to. It can be used to build digital currencies
like Bitcoin, and it can be used to build anonymity networks like Tor.
Encryption
can also be used to prevent people from installing iPhone apps that
didn't come from the App Store, to prevent people from recording movies
directly from Netflix, and to prevent people from installing Linux on a
Windows 8 tablet. And it can also be used to prevent
man-in-the-middle (MITM) attackers from adding malware to otherwise legitimate software updates.
In
short, encryption encompasses a whole host of uses, but here we are
focused on how we can use it to securely and privately communicate.
Software You Can Trust
When
Snowden uses the term "endpoint security" he means the security of the
computers on either end of the conversation that are doing the
encrypting and the decrypting, as opposed to the security of the message
when it’s in transit. If you send an encrypted email to a friend but
you have a keylogger on your computer that's logging the entire message,
as well as the passphrase that's protecting your encryption keys, your
encryption isn't worth very much.
Since Freedom of the Press
Foundation board members Glenn Greenwald and Laura Poitras broke the NSA
dragnet surveillance stories, a lot more information about US spy
agencies has been made public. Specifically, Bloomberg wrote about
voluntary information sharing programs between US companies and US spy agencies.
So
far the most shocking revelation about these information sharing
programs is that Microsoft has a policy of giving information about
vulnerabilities in its software to the US government before it releases
security updates to the public. The article says:
Microsoft
Corp. (MSFT), the world's largest software company, provides
intelligence agencies with information about bugs in its popular
software before it publicly releases a fix, according to two people
familiar with the process. That information can be used to protect
government computers and to access the computers of terrorists or
military foes.
This means that it's likely that NSA
has been handed the keys to any computer running Windows, Office, Skype,
or other Microsoft software. If you're running this software on your
computer, it's likely that, with enough effort, the NSA could compromise
your computer, and thus your encrypted communications, if you became a
target.
We've also learned from the
New York Times
that Skype, software that outside the security community has long had a
reputation of being a secure way to communicate, has been feeding
private conversations to the US government for the last five years.
Skype,
the Internet-based calling service, began its own secret program,
Project Chess, to explore the legal and technical issues in making Skype
calls readily available to intelligence agencies and law enforcement
officials, according to people briefed on the program who asked not to
be named to avoid trouble with the intelligence agencies.
Project
Chess, which has never been previously disclosed, was small, limited to
fewer than a dozen people inside Skype, and was developed as the company
had sometimes contentious talks with the government over legal issues,
said one of the people briefed on the project. The project began about
five years ago, before most of the company was sold by its parent, eBay,
to outside investors in 2009. Microsoft acquired Skype in an $8.5
billion deal that was completed in October 2011.
A Skype executive
denied last year in a blog post that recent changes in the way Skype
operated were made at the behest of Microsoft to make snooping easier
for law enforcement. It appears, however, that Skype figured out how to
cooperate with the intelligence community before Microsoft took over the
company, according to documents leaked by Edward J. Snowden, a former
contractor for the N.S.A. One of the documents about the Prism program
made public by Mr. Snowden says Skype joined Prism on Feb. 6, 2011.
Proprietary
software, such as much of what's released by Microsoft, Apple, and
Google, has another flaw. It's much more difficult for users to
independently verify that secret backdoors don't exist at the
clandestine demands of the surveillance state. Though recent reports
have shown that many companies hand over an unknown amount of
information in response to FISA requests, none have been shown to have
direct backdoors into their systems.
There is other software that's more reliable in this regard.
Free and open source software
is not always user friendly and it's not always secure. However when
it's developed in the open, with open bug trackers, open mailing lists,
open governing structures, and open source code, it's much more
difficult for these projects to have a policy of betraying their users
like Microsoft has.
GNU/Linux is an operating system that's
composed entirely of free and open source software. Examples of
GNU/Linux distributions include
Ubuntu,
Debian, and
Fedora Core. It's the most popular free software alternative to Windows and Mac OS X.
While free software projects still might include malicious code (see the
Underhanded C Contest),
the person writing the code needs to hide it cleverly and hope none of
the other developers, or downstream GNU/Linux package maintainers who
prepare and compile the source code of projects to include in their
distributions, notice.
In the 1990s, when civilian cryptography was becoming popular and the US government was doing
everything they could
to prevent it, the "cypherpunk" movement was born. Many pieces of
software intended to bring encryption to the people grew out of that
movement.
Cypherpunks write code. We know that
someone has to write software to defend privacy, and since we can't get
privacy unless we all do, we're going to write it. We publish our code
so that our fellow Cypherpunks may practice and play with it. Our code
is free for all to use, worldwide. We don't much care if you don't
approve of the software we write. We know that software can't be
destroyed and that a widely dispersed system can't be shut down.
— Eric Hughes, in his 1993 Cypherpunk Manifesto
That
code, that's open and public so that fellow cypherpunks may practice
and play with it, which anyone in the world can freely use, makes the
basis of the software and protocols that we can trust: TLS (the
encryption that powers HTTPS), LUKS (
disk encryption built-in to GNU/Linux), OpenPGP, Off-the-Record, and Tor.
The
Tactical Technology Collective has built a great
guide to open source security software that you can trust
to keep your communications private from surveillance. It's important
to remember that just using this software, and even using it perfectly,
cannot guarantee the security of your crypto. For example, we have no
idea if Apple has handed over
zero day
vulnerabilities to the NSA for iOS like Microsoft is reported to have
done. ChatSecure, which lets you have encrypted chat conversations on
iOS devices, is only as secure as the operating system that it's running
on.
It's important to remember that just because you use free
software doesn't mean you can't get hacked. People find zero day
exploits for free software all the time, and sometimes sell them to
governments and other malicious attackers. Free software users still
download malicious attachments in their email, and they still often have
badly configured and easily exploited services on their computers. And
even worse, malware is often very good at hiding. If a free software
user gets malware on their computer, it might stay there until the user
formats their hard drive.
Tails, which is a live DVD and live USB
GNU/Linux distribution that I will discuss in detail below, solves many
of these problems.
Anonymize Your Location with Tor
Tor
is a software service that allows you to use the Internet while
concealing your IP address, which is, in general, a fairly accurate
representation of your location. The
Tor
network is made up of over 3,600 volunteer servers called nodes. When
someone uses the Tor network to visit a website their connection gets
bounced through three of these nodes (called a circuit) before finally
exiting into the normal Internet. Anyone intercepting traffic will think
your location is the final node which your traffic exits from.
It's
important to remember that just because your connection to the Internet
may be anonymous that doesn't magically make it secure. EFF has made a
great
visualization of how Tor and HTTPS can work together to protect your privacy.
Like all good cryptography software, Tor is free software, complete with an open
bug tracker,
mailing lists, and
source code.
Documentation
for Tails, the live GNU/Linux distribution that forces all of the
user's network traffic to go through the Tor network, has
this to say about global adversaries:
A
global passive adversary would be a person or an entity able to monitor
at the same time the traffic between all the computers in a network. By
studying, for example, the timing and volume patterns of the different
communications across the network, it would be statistically possible to
identify Tor circuits and thus matching Tor users and destination
servers.
We still don't know whether or not NSA or
GCHQ counts as a global adversary, but we do know that they monitor a
large portion of the Internet. It's too early to know for sure how often
these intelligence agencies can defeat the anonymity of the Tor
network.
Even if they can, using Tor still gives us many
advantages. It makes their job much harder, and we leave much less
identifying data on the servers we connect to through the Tor network.
It makes it much harder to be the victim of a MITM attack at our local
network or ISP level. And even if some Tor circuits can be defeated by a
global adversary, if enough people are getting their traffic routed
through the same Tor nodes at the same time, it might be difficult for
the adversary to tell which traffic belongs to which circuits.
The easiest way to start using Tor is to download and install the
Tor Browser Bundle.
When Snowden
was answering questions on Guardian's website
from a "secure Internet connection", he was probably routing his
traffic through the Tor network. He may have also been using a
bridge to connect to the Tor network to make the fact that he was using Tor from his IP address less obvious to eavesdroppers.
Off-the-Record (OTR) Chat
Off-the-Record
(OTR) is a layer of encryption that can be added to any existing
instant message chat system, provided that you can connect to that chat
system using a chat client that supports OTR, such as
Pidgin or
Adium.
With OTR it's possible to have secure, end-to-end encrypted
conversations over services like Google Talk and Facebook chat without
Google or Facebook ever having access to the contents of the
conversations. Note: this is different than the "off-the-record" option
in Google, which is
not secure. And remember: while
Google and Facebook’s HTTPS connection is very valuable for protection
against your message while it’s in transit, they still have the keys to
your conversations so they can hand them over to authorities.
OTR is used for two things:
encrypting the contents of real-time instant message conversations and
verifying the identity
of people that you chat with. Identity verification is extremely
important and something that many OTR users neglect to do. While OTR is
much more user friendly that other forms of public key encryption, if
you wish to use it securely you still need to understand how it works
and what attacks against it are possible.
Service Providers and Jabber
Using
OTR only encrypts the contents of your chat conversations but not the
metadata related to them. This metadata includes who you talk to and
when and how often you talk to them. For this reason I recommend using a
service that isn't known to collaborate with intelligence agencies.
While this won't necessarily protect your metadata at least you have a
chance of keeping it private.
I also recommend you use an XMPP (also known as Jabber) service. Like email, Jabber is a federated, open protocol. Users of
riseup.net's Jabber service can chat with users of
jabber.ccc.de's service as well as
jabber.org's service.
OTR Clients
To use OTR you'll need to download software. If you use Windows you can download and install
Pidgin and separately the
OTR plugin. If you use GNU/Linux you can install the pidgin and pidgin-otr packages. You can read through
documentation on how to set up your Pidgin accounts with OTR. If you use Mac OS X you can download and install
Adium, which is a free software chat client that includes OTR support. You can read the
official documentation on how to get set up with OTR encryption with Adium.
There are also Jabber and OTR clients available for Android, called
Gibberbot, and for iOS, called
ChatSecure.
Your Key
When
you start using OTR, your chat client generates an encryption key and
stores it in a file in your user's home folder on your hard drive. If
your computer or smartphone get lost, stolen, or infected with malware,
it's possible that your OTR key can get compromised. If this happens, it
would be possible for an attacker with control over your Jabber server
to be able to mount a MITM attack against you while you're chatting with
people who have previously verified your identity.
Sessions
If
you want to use OTR to talk privately with your friends, your friends
also need to be using it. An encrypted session between two people
requires two encryption keys. For example, if you and your friend are
both logged into Facebook chat using Adium or Pidgin and you have both
configured OTR, you can chat in private. However if you are logged into
IM using Adium or Pidgin but your friend is chatting directly from
facebook.com in a web browser, you cannot have an encrypted
conversation.
If you wish to use Facebook or Google's services to
chat with your friends, I recommend disabling chat within the web
interface of these services and only using Adium and Pidgin to connect,
and encouraging all of your friends to do the same thing. Here is
instructions on how to do so for
Facebook and
Google.
When you start an encrypted OTR session, your client software will tell you something like this:
Attempting to start a private conversation with username@jabberservice...
Unverified conversation with username@jabberservice/ChatClient started.
If
you have already verified the OTR fingerprint of the person you're
talking with (more on this below) your session will look like this:
Attempting to start a private conversation with username@jabberservice...
Private conversation with username@jabberservice/ChatClient started.
When
you start a new OTR session, your OTR software and your friend's OTR
software send a series of messages back and forth to agree upon a new
session key. This temporary encryption key, which is only known by your
IM clients and is never sent over the Internet, is then used to encrypt
and decrypt messages. When the session is finished both clients forget
the key. If you start chatting with the same person later, your clients
generate a brand new session key.
In this way, even if an eavesdropper is logging all of your encrypted OTR conversations—which
NSA believes it is legally allowed to do,
even if you're a US citizen and they don't have a warrant or probable
cause—and later they compromise your OTR key, they cannot use it to go
back and decrypt your old conversations.
This property is called
forward secrecy, and it is a feature that OTR has which PGP does not. If
your PGP secret key (more on this below) gets compromised, and the
attacker has access to all the encrypted messages you've received, they
can go back and decrypt them all.
Read more about how forward secrecy works, and why all major Internet companies should adopt it for their websites,
here. The good news is Google
has already adopted forward secrecy, and Facebook
will implement it soon as well.
OTR Fingerprint Verification
When
you start a new OTR session with someone, your IM software receives the
fingerprint of her encryption key, and your OTR software remembers this
fingerprint. As long as someone uses the same encryption key when she
talks to you, presumably because she's consistently using the same
device, she will have the same fingerprint. If her fingerprint changes
then either she is using a different OTR key or you are both the target
of a MITM attack.
Without verifying keys you have no way to know that you're not falling victim to an undetected, successful MITM attack.
Even
if the person you're talking to is definitely your real friend because
she know things that only she would know, and you're using OTR
encryption, an attacker might still be reading your conversation.
This is because you might actually be having an encrypted OTR
conversation with the attacker, who is then having a separate encrypted
OTR conversation with your real friend and just forwarding messages back
and forth. Rather than your friend's fingerprint your client would be
seeing the attacker's fingerprint. All you, as a user, can see is that
the conversation is "Unverified".
The following screenshots show
Pidgin's visual indications of fingerprint verification. If you have
verified OTR fingerprints your conversation is private, and if you
haven't, your conversation is encrypted but you might be under attack.
You can't know for sure without verifying.
If
you click the Unverified link (in Adium it's a lock icon) you can
choose "Authenticate buddy". The OTR protocol supports three types of
verification: the
socialist millionaire protocol, a
shared secret,
and manual fingerprint verification. All OTR clients support manual
fingerprint verification, but not all clients support other types of
verification. When in doubt, choose manual fingerprint verification.
In
the screenshot above, you can see the OTR fingerprints for both users
in the session. The other person should see the exact same fingerprints.
In order to be sure that both parties are seeing the correct
fingerprints you both need to meet up in person, or talk on the phone if
you can recognize their voice, or find some other out-of-band but
secure method to verify fingerprints, such as sending a PGP encrypted
and signed email.
OTR fingerprints are 40 hexadecimal characters.
It's statistically impossible to generate two OTR keys that have the
same fingerprint, which is called a collision. However it is possible to
generate an OTR key that isn't a collision but looks like one on
cursory inspection. For example, the first few characters and last few
characters could be the same with different characters in the middle.
For this reason, it's important to compare each of the 40 characters to
be sure you have the correct OTR key.
Because you generally set up
a new OTR key each time you set up a new device (for example, if you
want to use the same Jabber account to chat from your Android phone with
Gibberbot as you use on your Windows PC with Pidgin), you often end up
with multiple keys, and therefore multiple fingerprints. It's important
to repeat the verification step on each device with each contact you
talk to.
It's still much better practice to use OTR without
verifying fingerprints than to not use OTR at all. An attacker that
attempts a MITM attack against an OTR session runs the very real risk of
getting caught, so likely this attack will only be used cautiously.
Logs
Here is an excerpt from the
chat logs, published by Wired, of a conversation between Bradley Manning and Adrian Lamo, who turned him in to authorities:
(1:40:51 PM) bradass87 has not been authenticated yet. You should authenticate this buddy.
(1:40:51 PM) Unverified conversation with bradass87 started.
(1:41:12 PM) bradass87: hi
(1:44:04 PM) bradass87: how are you?
(1:47:01
PM) bradass87: im an army intelligence analyst, deployed to eastern
baghdad, pending discharge for "adjustment disorder" in lieu of "gender
identity disorder"
(1:56:24 PM) bradass87: im sure you're pretty busy...
(1:58:31
PM) bradass87: if you had unprecedented access to classified networks
14 hours a day 7 days a week for 8+ months, what would you do?
(1:58:31 PM) info@adrianlamo.com : Tired of being tired
(2:17:29 PM) bradass87: ?
(6:07:29 PM) info@adrianlamo.com: What's your MOS?
As
you can see from "Unverified conversation with bradass87 started," they
were using OTR to encrypt their conversation, yet it still ended up
getting published on Wired's website and used as evidence against
Bradley Manning. While it's possible their conversation was under a MITM
attack, it's very unlikely. Instead both Bradley Manning's and Adrian
Lamo's OTR clients were logging a copy of their conversation to their
hard drives, unencrypted.
While it can sometimes be useful to keep
logs of conversations, it also greatly compromises your privacy. If
Pidgin and Adium didn't log OTR conversations by default, it's likely
that these chat logs would never have become part of the public record.
With
the release of OTR 4.0 in September 2012, Pidgin stopped logging OTR
conversations by default. Adium still logs OTR conversations by default
so you must manually turn off logging yourself, which is a bug in Adium.
Because Adium is free software with an open bug tracker, you can follow
and contribute to the conversations about fixing this bug
here and
here.
"Pretty Good Privacy" (PGP) Email Encryption
In 1991, Phil Zimmermann developed email encryption software called
Pretty Good Privacy, or PGP, which he intended peace activists to use while organizing in the anti-nuclear movement.
Today, PGP is a company that sells a proprietary encryption program by the same name.
OpenPGP is the open protocol that defines how PGP encryption works, and
GnuPG
(GPG for short) is free software, and is 100% compatible with the
proprietary version. GPG is much more popular than PGP today because
it's free for everyone to download, and cypherpunks trust it more
because it's open source. The terms PGP and GPG are often used
interchangably.
Unfortunately, PGP is notoriously hard to use, as exemplified by
Greenwald explaining how he could not initially talk to Edward Snowden because it was so difficult to set up.
Keypairs and Keyrings
As
with OTR, each person who wishes to send or receive encrypted email
needs to generate their own PGP key, called a keypair. PGP keypairs are
split into two parts, the public key and the secret key.
If you have someone's public key, you can do two things:
encrypt messages that can only be decrypted with their secret key, and
verify signatures
that were generated with their secret key. It's safe to give your
public key to anyone who wants it. The worst anyone can do with it is
encrypt messages that only you can decrypt.
With your secret key you can do two things:
decrypt messages that were encrypted using your public key, and
digitally sign messages.
It's important to keep your secret key secret. An attacker with your
secret key can decrypt messages intended only for you, and he can forge
messages on your behalf. Secret keys are generally encrypted with a
passphrase, so even if your computer gets compromised and your secret
key gets stolen, the attacker would need to get your passphrase before
he would have access to it. Unlike OTR, PGP does not have forward
secrecy. If your PGP secret key is compromised and the attacker has
copies of any historical encrypted emails you have received, he can go
back and retro-actively decrypt them all.
Since you need other
people's public keys in order to encrypt messages to them, PGP software
lets you manage a keyring with your secret key, your public key, and all
of the public keys of the people you communicate with.
Using PGP
for email encryption can be very inconvenient. For example, if you set
up PGP on your computer but have received an encrypted email on your
phone, you won't be able to decrypt it to read the email until you get
to your computer.
Like OTR, each PGP key has a unique fingerprint. You can find
a copy of my public key here,
and my fingerprint is 5C17 6163 61BD 9F92 422A C08B B4D2 5A1E 9999
9697. If you look at my public key you'll see that it's quite long and
would be hard to read out over the phone. A fingerprint is a short and
more convenient way to uniquely represent a key. With my public key you
can encrypt messages that only I can decrypt, provided that my secret
key has not been compromised.
Passphrases
The
security of crypto often relies on the security of a password. Since
passwords are very easily guessed by computers, cryptographers prefer
the term
passphrase to encourage users to make their passwords very long and secure.
Comic courtsey XKCD
For tips on choosing good passphrases, read the
passphrase section of EFF's Defending Privacy at the U.S. Border: A Guide for Travelers Carrying Digital Devices whitepaper, and also the
Diceware Passphrase Home Page.
In addition to protecting PGP secret keys, you also need to choose good passphrases for disk encryption and
password vaults.
Software
To install GPG, Windows users can download
Gpg4win, and Mac OS X users can download
GPGTools.
If you run GNU/Linux you should already have GPG installed. GPG is a
command line program, but there's software that interfaces with email
clients that makes it much easier to use.
You'll have to download
an email client to use PGP correctly. An email client is a program on
your computer that you open to check your email, as opposed to using
your web browser. The most popular PGP setup is the email client
Thunderbird with the
Enigmail add-on. Thunderbird and Enigmail are free software and run on Windows, Mac, and GNU/Linux.
Right
now PGP is very difficult to use securely from a web browser. While
some browser extensions exist that help with this, I would recommend
sticking to a desktop email client until the field of browser crypto
matures. It's possible to use PGP encryption with Gmail, but the easiest
way is to set up an email client like Thunderbird and run your Gmail
account through it.
Encrypting, Decrypting, and Signatures
You
can send encrypted emails and digitally sign them using the graphical
user interface provided by Thunderbird and Enigmail. Here's an example
of an encrypted email that I'm sending to myself. When I hit send, my
software took the body of the message and encrypted it using my public
key, making the content unintelligible to eavesdroppers, and indeed to
my email provider too.
When
I opened this email I was prompted to type in my encryption passphrase
to decrypt it. Since it was encrypted using my public key, the only way I
could decrypt it is with my secret key. Since my secret key is
protected with a passphrase, I needed to type my passphrase to
temporarily decrypt my secret key in order to use it to decrypt the
message.
PGP Isn't Just For Email
While
PGP is often used for email encryption, nothing stops you from using it
to encrypt anything and publish it using any medium. You can post PGP
encrypted messages on blogs, social networks, and forums.
Kevin Poulsen
published a PGP encrypted message on Wired's website
intended for Edward Snowden to read. As long as Wired has a copy of
Snowden's real public key, only someone in possession of Snowden's
secret key can decrypt this message. We don't know how Wired got a copy
of Snowden's public key.
Here's a message that was encrypted to my
public key. Without having access to my associated secret key, NSA
should not be able to break the encryption. (NSA, let me know if you get
it.)
-----BEGIN PGP MESSAGE-----
Version: GnuPG v1.4.12 (GNU/Linux)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=a8FR
-----END PGP MESSAGE-----
Identity Verification
As
with OTR, it's important that you verify the PGP keys of the people you
communicate with. In PGP you do this by using your secret key to
digitally sign someone else's public key.
From inside Thunderbird
you can click the OpenPGP menu and open Key Management. You can check
the "Display All Keys by Default" checkbox to see all of the keys in
your keyring. From here you can import keys from files, from your
clipboard, or from key servers. You can also generate new keypairs, and
view details of all the keys in your keyring.
As with OTR keys,
each PGP key has a unique fingerprint. And as with OTR, you need to read
out the entire fingerprint to be sure the public key you're looking at
actually belongs to the person you believe it belongs to.
You can
right-click on a key in this list and choose View Details to see its
fingerprint. Here are the details of the PGP key that the disk
encryption software
TrueCrypt uses to digitally digitally sign releases of its software.
Also
like OTR, you need to meet in person, talk on the phone, or use an
already verified OTR session to compare each character of the
fingerprint.
After you have verified that the public key you have
belongs to the person you think it does, you can click "Select action"
and choose "Sign Key".
In
the screenshot above I checked the "Local signatures (cannot be
exported)" box. In this way, you can sign PGP keys, which is necessary
for Enigmail and other PGP software to display security messages that
make sense, but you don't run the risk of
accidentally publishing who you communicate with to a PGP key server.
If
you receive an encrypted email from someone you know but the email is
not digitally signed, you can't be completely sure that it was actually
written by the person you think. It's possible it could be someone who
spoofed their email address or compromised their email account.
If
your friend tells you in this email that she generated a new key, you
need to meet up in person or talk to her on the phone and read out your
fingerprints before you can be sure that you're not under attack.
Attacks
If you don't verify identities you have no way of knowing whether or not you are the victim of a MITM attack.
Washington Post journalist Barton Gellman, who Edward Snowden trusted with information about the NSA's PRISM program,
wrote about his experience using PGP.
On
Thursday, before The Post published its first story, I made contact on a
new channel. He was not expecting me there and responded in alarm.
"Do I know you?" he wrote.
I
sent him a note on another channel to verify my digital "fingerprint," a
precaution we had been using for some time. Tired, I sent the wrong
one. "That is not at all the right fingerprint," he wrote, preparing to
sign off. "You're getting MITM'd." He was talking about a "man in the
middle" attack, a standard NSA technique to bypass encryption. I hastily
corrected my error.
Snowden was right to be cautious
and to insist that he check Gellman's new PGP fingerprint. PGP, if used
right, provides the tools necessary to prevent MITM attacks. But these
tools only work if the users are vigilant about identity verification.
Tails: The Amnesic Incognito Live System
Using
"properly implemented strong crypto systems" has a huge learning curve
and requires dedicated users who are willing to put in extra work to
take control of their own privacy, which is the main reason why OTR and
PGP are not currently in widespread use. But even when you use these
tools, how can you ensure "endpoint security" when you can't necessarily
trust your operating system or other software that you depend on every
day?
The solution is to use an entirely different operating system
comprised completely of "software you can trust" when you have a
serious need for real privacy.
Tails helps solve this problem.
Tails
is a live system that aims at preserving your privacy and anonymity. It
helps you to use the Internet anonymously almost anywhere you go and on
any computer but leave no trace using unless you ask it explicitly.
It
is a complete operating-system designed to be used from a DVD or a USB
stick independently of the computer's original operating system. It is
Free Software and based on Debian GNU/Linux.
Tails comes with
several built-in applications pre-configured with security in mind: web
browser, instant messaging client, email client, office suite, image and
sound editor, etc.
Tails is not for everyone. It's
still difficult to use compared to normal operating systems, it's slow,
it doesn't have all the software you may want. But Tails has all of
these properties because it's specifically designed to make it harder
for users to mess up their endpoint security. If you're in a position
where you think that NSA, or any other potential attacker, may want to
target you and your colleagues (the journalist/whistleblower
relationship comes to mind) it's one of the best tools available.
Because
Tails is not practical for daily computer use, it's a good idea to get
into the habit of using OTR and PGP in your normal operating system as
well. Tails won't help blunt the effects of dragnet surveillance by
itself, but encrypting as much as we can on a daily basis will.
Every
time you boot Tails you start from a clean slate. Anything you did in
your previous session on Tails gets erased and the system is reverted
back to the default state. This means that even if you get infected with
malware while using Tails, the next time you boot into it the malware
will be gone.
You can get started using Tails by
downloading
the DVD image and burning it to a DVD. You then need to boot to this
DVD. This step is different depending on what model computer you have,
but it often involves entering your BIOS and changing your boot order so
your computer tries booting from DVD before it tries your hard drive.
On newer PCs you might need to disable
UEFI "secure boot"
in the BIOS as well, which is the crypto that's used to make sure your
computer will only boot to digitally signed versions of Windows (which,
in affect, makes it harder for people to boot into non-Windows operating
systems). The
Tails website has more information on booting Tools from a DVD or USB stick.
After
booting to the DVD you have the option to install Tails on a USB stick,
which is especially useful because it allows you to configure a
persistent volume,
an encrypted section of your USB stick to store your data. Despite
starting from a clean slate each time you boot up, it's important for
you to be able to have access to your OTR and PGP keys, your Claws Mail
(more below) and Pidgin settings, and any documents you're working with.
Your persistent volume allows you to do this.
PGP and Email in Tails
I
discussed using Thunderbird with the Enigmail add-on to access your
email and use PGP, however this software doesn't come with Tails. Tails
comes with
Claws Mail which includes a PGP plugin.
Instead
of using Enigmail's PGP key management graphical user interface to
import, export, generate, view details about, and sign keys, you can
click on the clipboard icon in the top right of the screen and choose
Manage Keys to open
Seahorse, which provides these same features.
Workflow
To
get started having private communications with your friends and
colleagues with very high endpoint security, here are the steps you need
to take.
- Meet up with your friends face-to-face. Each person should bring their own laptop and USB stick.
- Download and burn a Tails DVD. Boot to Tails and create Tails USB sticks for each person.
- When
everyone has a Tails USB stick, each person should boot to Tails on her
own laptop and configure a persistence volume on her USB stick. Since
this volume is encrypted, each person should come up with her own secure
passphrase that she will need to enter each time she boots to Tails.
Everyone should reboot their laptops into Tails again and this time
mount the persistent volume.
- Each person should create a new pseudonymous Jabber account. One way to do this is to go to https://register.jabber.org/ in Iceweasel. Since Tails makes all Internet traffic go over Tor, this is effectively making an anonymous Jabber account.
- Each
person should open Pidgin and configure it to use their new Jabber
account and create a new OTR key. Everyone should add each other to
their buddy lists and start OTR sessions with eachother. Since everyone
is in the same room, this is the perfect time to compare fingerprints
and verify the identity of all parties so that you'll able to
communicate securely over the Internet in the future.
- Each
person should create a new pseudonymous email address as well. Some
email providers, such as Gmail, make it very difficult to create new
accounts while using Tor and staying anonymous, so find another email
provider to use instead. Make sure your email provider supports IMAP (so
you can use a desktop email client) over SSL (so your email client uses
encryption when communicating with the email srever). If everyone
chooses the same email provider, sending emails between accounts should
never leave that email server, which reduces the metadata about your
email usage available to anyone conducting dragnet surveillance of the
Internet.
- Each person should generate a new PGP key for their
email address. Like with disk encryption, it's important to choose a
strong passphrase when generating a PGP key.
- The PGP-enabled
email client that comes with Tails is called Claws Mail. Each person
should configure Claws Mail to use their new email address, and then
email a copy of their public key to all other people in the room.
- Each
person should import everyone else's public key into their keyring, and
should manually verify the PGP fingerprints. Don't skip this step. In
the end, each person should have a keyring containing signed keys of
each other person.
If a malicious attacker physically steals
your Tails USB stick, modifies it, and gives it back, he can compromise
all of the security of Tails. For this reason, it's important to keep
your USB stick with you at all times.
Had CIA Director and retired
four-star general David Petraeus and his biographer Paula Broadwell
decided to use Tails, Tor, OTR, and PGP, their
extramarital affair likely would have remained secret.
A Fighting Chance
Protecting
your privacy in the age of ubiquitous NSA surveillance is incredibly
complex. Gaining a basic understanding of the concepts involved, much
less actually using the software that's available, has an enormous
learning curve.
But even with
direct access to all the data traveling at the speed of light through the Internet's backbone fiber-optic cables, even with
cooperation of the major United States tech companies
(which are extremely difficult for people to boycott), the largest,
most powerful, and best funded surveillance apparatus that humanity has
ever seen cannot defeat mathematics.
The challenge of the new
cypherpunk movement is to make secure and verified end-to-end encryption
accessible to everyone, and turned on by default.
Author:
Micah Lee
A publication of the
Freedom of the Press Foundation, 2013
Copyright: Encryption Works: How to Protect Your Privacy in the Age of NSA Surveillance is licensed under a
Creative Commons Attribution 3.0 Unported License.
Download: PDF,
LibreOffice ODT
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