AN EXTENSIBLE AND PRIVACY- PRESERVING MOBILE ID Michael Hlzl, MSc - - PowerPoint PPT Presentation

AN EXTENSIBLE AND PRIVACY- PRESERVING MOBILE ID

Michael Hölzl, MSc Institute of Networks and Security, JKU Linz IKT Sicherheitskonferenz 2017

• 26. September 2017, Villach

Extensibility in a Privacy-preserving eID 2

Digital Identity: State of the Art

 OpenID: some (large) providers, many (small) consumers

 Facebook  Google  ...

 FIDO

 U2F  UAF

 Governmental eIDs (German ePerso, Austrian

“Bürgerkarte”, etc.) → optimized for web page login, not physical identification

Extensibility in a Privacy-preserving eID 3

Motivating Scenario: Convergence of Security-Critical Services

Extensibility in a Privacy-preserving eID 4

Mobile eID Use Case 1: Driving license verification by Police

 All relevant attributes need to be

presented, e.g.

 Name  Date of birth  Full-resolution photo  Vehicle classes  Restrictions/limitations  ...

 Offline ID attributes transfer and

• ffline verification

 Should also work when mobile

phone battery is empty!

Place of Birth:

Ulm, Germany

Citizenship:

USA, Switzerland

Signature: Givenname:

Albert

Surname:

EINSTEIN

Date of Birth:

1879-03-14

ID number:

123456789

Sex:

M

GENUINE

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Mobile eID Use Case 2: Age Verification

 Age verification by e.g.

 Automated vending machines  Bouncers at clubs  Entrance staff for birthday

rebate promotions  Only age attribute should be

transferred in privacy- sensitive manner

Place of Birth:

Ulm, Germany

Citizenship:

USA, Switzerland

Signature: Givenname:

Albert

Surname:

EINSTEIN

Date of Birth:

1879-03-14

ID number:

123456789

Sex:

M

GENUINE

> 16 years

Extensibility in a Privacy-preserving eID 6

Mobile eID Use Case 3: Time-based Ticket for Public Transport

 Typical for public transport

 Monthly  Yearly  (any time period)

 No identifiers should be

transferred

 Location traces are highly

sensitive personal data

Place of Birth:

Ulm, Germany

Citizenship:

USA, Switzerland

Signature: Givenname:

Albert

Surname:

EINSTEIN

Date of Birth:

1879-03-14

ID number:

123456789

Sex:

M

GENUINE

> 16 years

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Extensible and Privacy-preserving Mobile eID

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Building Blocks

 NFC Secure Element (SE)

 Protect identity keys & integrity assurances  Code isolation  Can be powered by the NFC field  Downside: constrained performance (see [1])

 Attribute-based Credentials (ABC)

 Issuance of attributes within a cryptographic

container (credential) by trusted authority

 Allows selective disclosure (SD) of these attributes  Downside: operations can become time-consuming

(especially on an SE, e.g. [2])

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Extensibility and Privacy-preserving Mechanisms

 Domains

 eID derives pseudonym for each enrolled

domain

 Domain can add data attributes to eID (e.g.

transport ticket validity period)

 Trust-on-First-Use (TOFU) database protects

against pseudonym linking  Profiles

 Controlled by user  Defines the set of accessible attributes  Can be associated with a domain

Givenname:

Albert

Surname:

EINSTEIN

ID number:

123456789 derive

Extensibility in a Privacy-preserving eID 10

Secure Channel Protocols

 Purpose

 eID validation  Profile selection  Attribute exchange

 We define two processes

 Domain enrollment  Verification

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Protocols: Domain Enrollment

 Initiated by eID holder on mobile device  User approves with PIN/password  Secure channel between SE and

domain manager

 Based on Alpár and Hoepmann in [3]  ABC to authenticate session keys

 Use of the nonce of the selective

disclosure (SD) mechanism  Combined with a domain pseudonym

derivation

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Protocols: Domain Enrollment

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Evaluation

 Storage Space on SE

 Each enrolled domain requires: 1x EC-point, 1x profile description (e.g.

4 bytes for 32 attributes) ➔ 69 bytes  Computation times on SE  Domain enrollment  Verification

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Austrian mobile Driving License (AmDL)

 Current prototype at research center u'smile

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Conclusion

 Mobile eID for

real-world identification

 Possibility to use it for many services  Protocols for efficient attribute

exchange

 Protocols can be run on smart cards

within reasonable time (below 2s)

Place of Birth:

Ulm, Germany

Citizenship:

USA, Switzerland

Signature: Givenname:

Albert

Surname:

EINSTEIN

Date of Birth:

1879-03-14

ID number:

123456789

Sex:

M

JOHANNES KEPLER UNIVERSITÄT LINZ Altenberger Str. 69 4040 Linz, Österreich www.jku.at

AN EXTENSIBLE AND PRIVACY- PRESERVING EID

Michael Hölzl, MSc Institute of Networks and Security, JKU Linz hoelzl@ins.jku.at

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Bibliography

[1] M. Hölzl, R. Mayrhofer, and M. Roland. Requirements for an Open Ecosystem for Embedded Tamper Resistant Hardware on Mobile Devices. In Proceedings of International Conference on Advances in Mobile Computing & Multimedia, MoMM ’13, pages 249–252. ACM, 2013. [2] P. Vullers and G. Alpár. Efficient Selective Disclosure on Smart Cards Using Idemix. In Policies and Research in Identity Management (IDMAN), pages 53–67. Springer Berlin Heidelberg, Apr. 2013. [3] G. Alpár and J.-H. Hoepman. A Secure Channel for Attribute-based Credentials: [Short Paper]. In Proceedings of the 2013 ACM Workshop on Digital Identity Management, DIM ’13, pages 13–18. ACM, 2013.

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Credits

 Icons

 SIM Card by Arthur Shlain from the Noun Project  People pattern by Gregor Cresnar from the Noun Project  Agreement by Chameleon Design from the Noun Project  Smart Phone by Emily Haasch from the Noun Project  Airplane Ticket by Creative Stall from the Noun Project  Bus tickets by Iulia Ardeleanu from the Noun Project  Loyalty Card by icon 54 from the Noun Project  Business card by Karthik Aathis from the Noun Project