authentication with privacy and security · problems with online logins … user unfriendly …...

13
Authentication with Privacy and Security —the maths behind attribute-based credentials— Greg Alpár [email protected] Open Universiteit, Radboud Universiteit August 25 and September 1, 2018 1 / 13

Upload: others

Post on 15-Oct-2019

4 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Authentication with Privacy and Security

—the maths behind attribute-based credentials—

Greg Alpá[email protected]

Open Universiteit, Radboud Universiteit

August 25 and September 1, 2018

1 / 13

Page 2: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Who is this guy?

… Maths and maths teaching (MSc) – ELTE… Mathematics for Industry (MTD, PDEng) – TU/e… Computer Science (PhD) – RU… Assistant Professor (UD) – OU (, RU)

… Number Theory, Abstract algebra… Coding theory, Cryptography… Privacy

… ABC Technology Workshop

… Open Maths – Comenius Grant (Innovative UniversityEducation)

2 / 13

Page 3: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Attribute-based credentials

3 / 13

Page 4: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

4 / 13

Page 5: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Problems with online logins

… User unfriendly… Often insecure… Often identifying

5 / 13

Page 6: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

6 / 13

Page 7: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Problems with online logins

or they are:… Always identifying… Highly centralized & traceable

Attribute-based credentials to the rescue!

7 / 13

Page 8: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

What is this ABC?

… Attribute-Based Credentials (ABCs)… Specifically IBM’s Identity mixer (Idemix) based on the

Camenisch–Lysyanskaya signature… A credential is a cryptographic container

… Signature: authenticity, integrity, ‘verifiability’… . . . on a block of messages, called attributes… Randomisation (blind)… Selective disclosure

8 / 13

Page 9: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Demo time

9 / 13

Page 10: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

Attribute-based credential – selective disclosure

User ServiceProvider

sk

> 12

> 16

> 18

> 21

1. Request service

2. Policy

3. Show credential> 12

> 12

> 12

> 18

> 12

blackboard...10 / 13

Page 11: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

ABC issuing

Usersk

IdP2

IdP1

...

IdPn

xa1

a2...

an

sk

bn

b1

b2...

bn

sk

Issuance

Issuance

11 / 13

Page 12: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

An ABC system

IdentityProvider

User ServiceProvider

ska1...

ana.

Requ

estcre

denti

al

b.Iss

uecre

denti

al

1. Request service

2. Policy

3. Show attributes (sel. disclosure)

Trust

12 / 13

Page 13: Authentication with Privacy and Security · Problems with online logins … User unfriendly … Often insecure … Often identifying 5/13

ABC summary

… Independence between issuing and showing: time and protocol… Credential: security for the system

… Authenticity… Integrity… Non-transferability

… Credential: privacy for the user… Selective disclosure… Issuer unlinkability (even the issuer can not identify a

non-identifying attribute when it is disclosed)… Multi-show unlinkability (it is impossible to distinguish

whether two of the same non-identifying, disclosedattributes belong to the same user)

… ...and all of this with elegant mathematics!

T H A N K Y O U !

13 / 13