1. Anonize “Large Scale Anonymous System”
Proposed by:
Susan Hohenberger, Steven Myers, Rafael Pass, abhi shelat
Presented by : Vijendra Rana

2. Lets start with a Question Will You fill out this 15 min survey?

3. What about now ??

4. Agenda Motivation already seen 3 important things Existing technique
Important definitions
Back to Anonize
How it works
Results
Technology in a Nutshell
I will come back to the question

5. 3 Important thing Anonymity (Obvious)
Authenticity(I want to spend my money wisely)
Only one response per user (Think about me giving 100$ 10 times to same person)

6. Existing Technique
3rd party survey like Survey Monkey Can we trust them
Is their any link between our response and our identity (If not what if I keep on filling multiple surveys)
What if somebody break into their system to get my info (Cornell university computer records including SSN)
Can we trust a 3rd party for some financial, Medical Surveys (Is it legal)

7. Link between our response and identity Cryptographic Voting Technique
2 step in each survey
users authenticate themselves to a server and anonymously check out a single-use token ,which carries no link to user identity
users participate in the specified survey using their token.
But the problem here the 2 steps should have proper time lag or else there Is certainly a time link. Sometimes the time gap can be a day
Makes surveys really inconvenient – Who want to wait for a day

8. Any solution Yes we have
Anonize – they use the cryptographic Techniques to make sure
Anonymity
Authenticity
One response (Response can be edited
before deadline)
Are we saving any link ?? Let’s see

9. Before we dive into system Some definitions first Commitment Scheme
A commitment scheme
Lets a sender commit to a
Message without revealing
that message to a receiver

10. PRF
A PRF is a seeded deterministic function that maps any input to a random looking output, assuming one has no knowledge of the seed (Important thing Same input Same output)

11. Interactive Zero Knowledge Proof
Taken from UCL slides lets say alice says I have a positive number

12. An Analogy Ali Baba Sesame secret but no idea what the secret is
We all know reporter Know the
secret but no idea what the secret is

13. NIZP
Only one proof sent verifier agree
Simulation going on

14. Back to Anonize – The Setup
Lets take the University Survey System (3 Steps)
Registration
Survey Creation
Survey execution

15. Registration with a RA(Registration Authority aka University)
A user with identity id registers with the RA by sending a commitment to a random seed sid of a pseudo-random function (PRF) F and providing a NIZK that the commitment is well-formed. If the user has not previously been registered, the RA signs the user’s name along with the commitment. The signature returned to the user is its “master user token”.

16. Survey created by SA(Survey Authority aka Teacher)
To create a survey, an SA publishes a list of signed user identities along with a survey id, vid.

17. Response (by User client aka Student)
To complete a survey for survey id vid, a user id generates a single-use token Fsid (vid) (by evaluating the PRF on the seed sid with input vid) and presents a NIZK that it “knows a signature by the RA on its identity id and a commitment to a seed sid” and that it “knows a signature by the SA on its id” and that the single-use token is computed as Fsid (vid).

18. Some Math Now
An ad-hoc survey scheme is a tuple of algorithms (GenRA, GenSA, RegRA,RegU, GenSurvey, Authorized, Submit, Check)

19. Registration

20. Survey Register

21. Completing a Survey

22. What else in the paper Math that shows the correctness of algorithm
Proof of security
Concurrent security

23. Experiment and Result BN curve for a lot of low configuration machine
BLS curve low number of high configuration machines

24. Technology in a nut shell by Anonize
User Registration
When you register your Anonize app, the app receives in return a cryptographic "master token". Think of this master token as a stamp. This stamp can be used to mint "digital coins", which will be used to submit surveys.
Only Authorized Users Can Submit
Using their master token, a user can mint one and only one coin for any survey they are authorized for. On the other hand, no user can forge a coin for surveys they are not authorized for. Anyone can verify whether a coin is "valid" for a particular survey.
Coins are Unlinkable
Anyone can verify that the coin minted by a user is valid (that is, it corresponds to a user that is authorized to submit in the survey) but there is absolutely no link between the user and the coin. The coins can therefore be used to replace user names when submitting a survey.

25. Full circle Now I think we can do it ??

26. Thanks Any Questions