Safe communication for activists

How to prepare an action safely without leaking information

Overview

Focus of today : prepare actions without information leaks

Concentrate on cell phones and email 1. Most common information leaks : overview 2. Telephone guidelines : keep it practical 3. Email : how to encrypt your email and how it

works

Drawbacks of advancing technology

Data storage hardware has become much cheaper during the last decade

How much do you pay for a 500 GB hard disk ? How much did you pay for 5 MB in the eighties ?

Data mining hardware is much cheaper Data mining software is getting more advanced

Monitoring ”less important” action groups becomes less costly

Investing hours in preparing an action, arriving at the moment of action with everything blocked is an experience most of us would like to avoid

Audio tapping without inside installed equipment

SOURCE : BBC Website

Standby troubles

Outsiders can mess with your phone

Cell phone companies are reluctant to give information on :

Standby modes (alarm clock) Privacy : what they pass on to

intelligence agencies Encryption : is non open

source and known methods are cracked easily

Special features : standby modes (software and hardware implementation)SOURCE : BBC Website

Evil cell phones

Your communication is easily captured Your location is easily determined up to 20 –

100 m ”Switched-off” phones are technologically

capable of sending information Your social networks become more visible (you

are calling some people from certain locations) Cell phones with the batteries removed or

acoustically isolated phones behave nicely

Conversation tapping

It is not necessary to put a receiving antenna in the neighborhood of your cell phone

Calls are routed through centrals No battery : no energy : no waves : no leaks ! ”Switched off” not always means switched off

Sort of standy state : a trigger signal can reactivate your phone : you won't notice it when it is happening

Ardito case : judge's memorandum opinion stating tapping is allowed even when phones are switched off

Siemens patent : reactivating cell phones in case of emergencies

The Ardito case

<<The government applied for a "roving bug," that is, the interceptionof Ardito's conversations at locations that were "not practical" tospecify, as authorized by 18 U.S.C. § 2518(11)(a). Judge Jonesgranted the application, authorizing continued interception at thefour restaurants and the installation of a listening device inArdito's cellular telephone. The device functioned whether the phonewas powered on or off, intercepting conversations within its rangewherever it happened to be.>>

United States District Court,S.D. New York.UNITED STATES of America,v.John TOMERO, et al., Defendants.No. S2 06 Crim. 0008(LAK).Nov. 27, 2006.

MEMORANDUM OPINION

LEWIS A. KAPLAN, District Judge.

The Siemens patent

<< ... This activates an emergency call routine. The emergency routine comprises the following steps, which are partially optional: 2. In case the mobile is switched off it may activate the mobile. In case or as soon as the mobile is switched on, a module for broadcasting over the emergency network, that may operate on frequencies distinct from those of the cellular communication network, is activated. This activation can be done optionally also regardless of the possibility to establish a connection to a cellular communication network. ...>>

http://www.wipo.int/pctdb/en/wo.jsp?IA=EP2002012292&DISPLAY=DESC

Software ”roving bugs”

<< Nextel and Samsung handsets and the Motorola Razr are especially vulnerable to software downloads that activate their microphones, said James Atkinson, a counter-surveillance consultant who has worked closely with government agencies. "They can be remotely accessed and made to transmit room audio all the time," he said. "You can do that without having physical access to the phone." >>

http://news.zdnet.com/2100-1035_22-150467.html

Network mapping with cell phones

Prepaid calling doesn't help when they want to relate who you are calling

Unless everyone in a group changes cell phones and SIM cards, relating the calls of the group is easy, which is needed is :

A person monitoring locations / calls / SIM / telephone numbers

A person looking in the database of previous monitoring reports and using software to link information

It needs time and resources to do so

Your cellphone reveils your location

Triangulation : three basis stations record your distance to the stations → geometry → your position is known up to 20 – 100 m

Distance measurement is part of standard working procedure of cell phone technology!

If quite some cell phone users are crowded near a suspect location → maybe it is interesting to have look there

Simultaneously switching off your cell phones might be giving away important information too

DIY-ers : beware of pitfalls

Faraday cages : a completely sealed metallic box must be sealed really well →

Minor wave leaks are sufficient for cell phones to do their job anyway

Metal cookie boxes are leaky as can be Loud sounds next to cell phone : if sound is

”structured”, then removing your ”noise” is done in a second :

Loud music : doesn't work (even chaotic death metal)

Loud machines : don't work

Cell phone guideluines

Don't use a cell phone unless you really have to Think of the eighties !! Prepare your action some time earlier, which gives

you time to drop by and enjoy real company When having a meeting :

Remove battery or store cell phones in an adjacent room from where you normally cannot overhear the meeting (then no sound can be picked up by the microphone and only noise can be sent)

When going to your action location : Remove battery of cell phones and leave phones

switched off until the very start of the action

Email issues

Intercepting email conversation is really easy The only robust way to prevent leaking

information by email, is good encryption Before sending your email, you convert it in

something undecipherable One or more keys :

Encrypt your email : make it unreadable Enable you to decipher encrypted emails

Encryption

Transforming your email into unreadable cryptic writings : you need a secret code

1. Message : ”action” 2. Code : one letter further up the alphabet 3. Encrypted message : ”bdujpo” 4. Decription : one letter back down the alphabet 5. Decripted message : ”action”

THE ENCODING PROCESS IS REVERSIBLE

IF SOMEONE KNOWS THE CODE SHE / HE CAN DECRYPT

Symmetric encryption

Sarah has to walk to Tom and give him the encryption key

Not practical : sometimes the key is sent over the internet, which is not safe in most cases

If someone intercepts the key, your conversations are compromized

SARA

TOM

THE EVIL INTERNET

Sara sends an email to Tom with asymmetric encryption

Sarah encrypts her email with Tom's public key, which everyone can download from the internet and she sends the encrypted mail over the internet

The encrypted email can only be deciphered by Tom by using his private key, his private key doesn't leave his personal computer and is protected by a password

SARA TOM

THE EVIL INTERNET

PUBLIC KEYPRIVATE KEY

Now wait a minute !

If everyone knows the public key, how come nobody can decipher Sarahs message? After all, it was the public key Sarah used to encrypt the message.

Public encryption must be irreversible !! Tearing paper into small pieces, burn 'em, throw ashes in the sea One-way trapdoor (turn back the time) function All mathematicians on earth are smarter than intelligence agencies ?

Are you really sure it is impossible to derive Tom's private key when you know what his public key is ?

You can only do this by solving a VERY difficult mathematical problem Factorization problem of very large primes All mathematicians on earth are smarter than intelligence agencies ?

A bit of mathematics (two slides only – don't run away ... yet)

2 . 2 . 2 = 2^3 = 8 and (2 . 2 . 2) . (2 . 2 . 2) = (2^3)^2 = 2^(3 . 2)

5 = 19 mod 7 because if you try to divide 19 by 7, there is 5 left over (19 = 2 . 7 + 5 )

A prime is a natural number (1 , 2 , ...) with divisors itself and 1

1. Choose two large distinct prime numbers p and q 2. Compute n = p q 3. Compute f = (p – 1)(q – 1) : Euler's totient function 4. Choose e such that

1 < e < f f and e share no other factors than 1 (”they are coprime”)

5. Determine d such that : d . e = 1 (mod f) Public key : (n, e) Private key : (n, d)

Encrypting the message

Convert a text message into a number M

Sara encrypts her message M : she sends the undecipherable text c = M^e (mod n)

Tom recovers the message by calculating : M = c^d (mod n)

Why does this work ?

Since e . d = 1 + k . f (by step 5) M^(e . d) = M^(1 + k . f) = M . (M^k)^f = M (mod n)

Last step follows from Euler's theorem (see step 3) You really need d (part of private key) in order to decipher the

message

You can only derive d if you can find the original primes p and q

PGP : pretty good privacy

PGP encrypts every new message with a new symmetric key (session key)

The symmetric key is encrypted with asymmetric encryption (public and private keys)

Some precautions are taken to make it impossible to guess the keys from monitoring multiple emails (adding random nonsense)

Open source software (OpenPGP) gets updated regularly and takes mathematical pittfalls in account

Getting PGP to work on your computer

www.openpgp.org : the developer's website but maybe too much information and too techie

http://enigmail.mozdev.org : Enigmail is a pgp plugin for Mozilla Thunderbird email program

Click on ”Quick start guide” STEP 1 : Install GnuPG on your platform

(Mac/Linux/Windows) STEP 2 : Install Enigmail

The first time you use pgp, the program itself guides you through the setup

Take your time to get used to pgp !

Pgp functionality in Thunderbird

Thunderbid after installation plugin

PGP/MIME makes encrypting attachments easy

You have to know whether the recipient uses MIME too

Pgp Preferences

Account settings

Some considerations

Use a seperate emailadress with a good emailclient to use pgp

You check ”always encrypt messages” : avoid sending unencrypted mails by accident

Look for your friend's key on a keyserver OpenPGP → Keymanagement → keyserver →

search for keys Make your own key available for your friends :

OpenPGP → Keymanagement -->right click your key → upload public keys to keyserver

PGP : concluding remarks A lot of PGP workshops are being given, but still not a lot

of people are using it

If you are a good computer DIY-er : Take your time to install PGP Allow yourself some practice time Read this presentation for tips and tricks

Computers are annoyant machines never doing what they should do, in your opinion, then :

Ask someone who is already using pgp If it is installed, and you played around with it a bit, it becomes a

second nature If you are a group of people, have a techie come over and install

it on your computers

Use safe passwords

All passwords of less than 6 characters are unsafe, use at least 8, 10 is even better

Brute force attacks (trying every possible password – with some good starting guesses) are more succesfull than ten years ago

Easy to remember passwords are easy to crack Difficult to crack passwords are difficult to remember

Use a lot of characters (8 - 10), and use a large set of characters (AaBb94-+:!)

Example : three letter password : 26 . 26 . 26 = 17576 vs. 256 . 256 . 256 =16777216

Solution → ”code” your password

Easy to remember and difficult to crack passwords

1. Invent a code (here is an example, but invent your own)

a → 6 i → 1 o → Q t → + l → / 2. Invent a ”special rule” The third symbol is always ”:” and at the end I

add : ”{-}” Appelboom → 6p:e/bQQm{-} Lappersfort → /6:persfQr+{-} Queerilla → Qu:er1//6{-}