TU Wien:Privacy-Enhancing Technologies VU (Weippl)/Midterm Exam 2018-11-13

1) What can be used to circumvent DNS censorship?

• Using Tor
• Using the IP
• 1.1.1.1
• 2.2.2.2

2) Which are valid onion service addresses?

• A valid v3 56 character address
• http://tuwienpetslectur.onion
• http://facebookcorewww1.onion (invalid, last digit is 1)
• http://facebookrocksmyworld.onion (invalid, too long)

3) What is privacy, what are PETs?

• Privacy is a human right, PETS are means to assure it
• More than one PET is not necessary
• DSGVO contains lots of measures to achieve computer-security und privacy

4) What does the GFW of China use?

• Manual checklists
• DPI
• DNS (blocking/redirecting?)
• Active probing of tor bridges and blocking them

5) Which statements about PRISM are true?

• Collects data at rest
• Collects network traffic (passively)
• Collects data from US companies
• Collects mainly data from European Software companies

6) What are common techniques for censorship?

• IP blocking
• Getting providers to remove content

7) v3 vs v2 onion services, v3 uses:

• Use 56 character addresses of the whole public key
• Use to introduction points
• Use to rendezvous points
• v3 uses Ed25519

8) What is true about Tor

• Exit relays connect the Tor network to the internet
• running a relay can be problematic
• The DA choses the relays for a client for each connection
• A client chooses the relays last hop first

9) What is true for Tor hidden services?

• There are seven relays between a client and the provider of a hidden service

10) Which statements about Privacy and Security are true?

 ..

11) Tor uses

• asymmetric encryption
• symmetric encryption
• Diffie-Hellman key exchange
• TLS

12) Which of the following threat models are prevented by Tor

• Passive attacks of a global observer
• Attackers running malicious relays
• Attackers observing the communication of exit relays
• Attacks on complex protocols like HTTP

13) The main differences between onion and garlic routing are

• Garlic routing is mainly used for darkweb
• Tor/Onion routing is used for usual web activities like websurfing
• Garlic routing protects against a global observer

..

14) Unobservability ...

• means that one does not know if a certain entitiy is communicating
• is ensured by DC nets

.. ..

15) Which of the following statements about Tor numbers are correct

• There are exactly 10 DAs
• There are about 6000 to 7000 relays and 500 - 800 exit relays
• There are exactly 8000 relays
• There are 15000 users

16) Using Tor

• Only if you run a relay you get full anonymity
• You should use HTTPS, IMAPS.. because Tor does not protect against attacks on unsafe protocols
• Many browsers leak information, hence the TBB has been introduced

17) iwas mit Remailer (type III)

18) iwas mit OONI und RIPE

• RIPE can be used to execute arbitrary complex commands on nodes