Privacy Preserving Back-up and

Recovery of Emergency Data

Seminar on System Security for Master

SS2010

Zdravko Danailov

Outline

�Introduction�The Telematics infrastructure

�Electronic Health Card

�Health Professional Card

�Hardware Security Module

�Emergency data

�Existing/ proposed solution for Back-up/Recovery of

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�Existing/ proposed solution for Back-up/Recovery of emergency data�Existing/proposed solution

�Disadvantages�Renewing of the eHC (lost, defect or expired)

�Recovery of emergency data on the eHC

�Krawczyk’s Secret Sharing Scheme

�Our proposal solution

�Conclusion

Basics: The Telematics infrastructure

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�Overview of the entire architecture

�Primary systems architecture

Basics: Electronic Health Card (eHC)

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�eHC�Solution design by the Fraunhofer Institute

�Chip card (HSM)

�Content (emergency data, ePrescription)

Basics: Health Professional Card (HPC)

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�HPC�Solution design by “Elektronischer Arztausweis”-work group

�individually programmed access authorization card for health professionals (e.g. doctors, pharmacists)

�Doctor-to-doctor Method (D2D)�Doctor-to-doctor Method (D2D)

�Creation of medicament documentation via the web-based software star.net®

Basics: Hardware Security Module (HSM)

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�HSM�Use as card (eHC, HPC) or eHC chip card terminal

�Connection via USB-port or serial interface

Basics: Emergency data

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�Emergency data�relevant diagnoses, medication or allergy/ intolerance

Emergency data�declaration for organs’ spending

Outline

�Introduction�The Telematics infrastructure

�Electronic Health Card

�Health Professional Card

�Hardware Security Module

�Emergency data

�Existing/ proposed solution for Back-up/Recovery

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Zdravko Danailov

�Existing/ proposed solution for Back-up/Recovery of emergency data�Existing/proposed solution

�Disadvantages�Renewing of the eHC (lost, defect or expired)

�Recovery of emergency data on the eHC

�Krawczyk’s Secret Sharing Scheme

�Our proposal solution

�Conclusion

Existing/ proposed solution: Overview

�Overview� Person involved: patient, doctor, paramedic

�HSM: chip cards – eHC, HPC; chip card terminal;

� Processing emergency data: Back-up, Recovery, Update

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Existing/ proposed solution by gematik

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�Authentication

�Processing of emergency data

�Creating Back-up (on A4 �Creating Back-up (on A4 paper or in local database)

�Recovery of emergency data on eHC

Disadvantages of the solution: Renewing of the eHC(lost, defect or expired)

�Renewing of the eHC (lost, defect or expired)

�Obtaining the emergency data from A4 paper

�Creation of A4 paper with emergency data – optional

�A4 paper – lost, stolen or deleted

�Exposing of private data

�Obtaining the emergency data from primary system’s database

�Temporary Back-up may be: 1.deleted 2.not accessible

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Disadvantages of the solution: Recovery of emergency data on the eHC

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�Recovery of emergency data on the eHC

�Obtaining the emergency data from A4 paper

�Creation of A4 paper with emergency data – optional

�A4 paper – lost, stolen or deleted

�Exposing of private data

�Obtaining the emergency data from primary system’s database

�Temporary Back-up may be: 1.deleted 2.not accessible

Outline

�Introduction�The Telematics infrastructure

�Electronic Health Card

�Health Professional Card

�Hardware Security Module

�Emergency data

�Existing/ proposed solution for Back-up/Recovery of

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Zdravko Danailov

�Existing/ proposed solution for Back-up/Recovery of emergency data�Existing/proposed solution

�Disadvantages�Renewing of the eHC (lost, defect or expired)

�Recovery of emergency data on the eHC

�Krawczyk’s Secret Sharing Scheme

�Our proposal solution

�Conclusion

Secret Sharing Scheme (SS)

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�Secret Sharing Scheme (n,m)

� Invented by both Adi Shamir and George Blackley independently of each other in 1979

�Method for distribution of a secret S among a group of n-participants

�Reconstruction is possible only when a sufficient number of shares are combined together

Shamir’s Secret Sharing Scheme

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�Shamir’s Secret Sharing Scheme (n,t)�Based on polynomial interpolation

�Distribution

� polynomial of degree t-1, secret S = k0, coefficients kt-1,…,k1 picked at random

� n points on the curve; n participants

�Reconstruction

� at least t out of the n players reveal their points

� sufficient information

� secret S

� information-theoretically secure

� storage efficient

� Size of shares = size of secret |S|

Information Dispersal Scheme (IDS)

�Information Dispersal Scheme (n,m)

�Based on error correcting codes (e.g. Reed-Solomon Code)

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�Method for distribution of information F among a group of n-participants

�Reconstruction is possible when sufficient number of fragments (≥m) are combined together

�Secrecy is not important

�size of fragments =

Krawczyk’s Secret Sharing Scheme

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�Krawczyk’s Secret Sharing Scheme (n,m)

�Combination of SS and IDS

�computationally secure

� less storage and bandwidth in comparison to Shamir’s SS

�size of shares = |si| <|S|

Outline

�Introduction�The Telematics infrastructure

�Electronic Health Card

�Health Professional Card

�Hardware Security Module

�Emergency data

�Existing/ proposed solution for Back-up/Recovery of

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Zdravko Danailov

�Existing/ proposed solution for Back-up/Recovery of emergency data�Existing/proposed solution

�Disadvantages�Renewing of the eHC (lost, defect or expired)

�Recovery of emergency data on the eHC

�Krawczyk’s Secret Sharing Scheme

�Our proposal solution

�Conclusion

Our proposal solution: Overview

�Overview� Person involved: patient, doctor, paramedic

�HSM: chip cards – eHC, HPC; chip card terminal;

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�Properties� tolerate no non-availability

�preserve privacy

�no encryption but secret sharing

Our proposal solution: Back-up

�Back-up of emergency data�Authentication (via e.g. ID-patient/ ID-doctor, ID-eHC/ID-HPC,

Fingerprints, different types of digital signatures, PIN, etc.)

�Complete the form for emergency data and/ or form for organs’ donation

�Confirmation of the data, e.g. via fingerprint by the patient and doctor

�Back-up

� using Krawczyk’s SS – executed online via e.g. VPN

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� using Krawczyk’s SS – executed online via e.g. VPN

� using a portable device (e.g. USB-Stick) – executed offline

Our proposal solution: Recovery

�Recovery of emergency data�Authentication (via e.g. ID-patient/ ID-doctor, ID-eHC/ID-HPC,

Fingerprints, different types of digital signatures, PIN) on HSM

�Recovery of emergency data is possible

� using Krawczyk’s SS – executed online via e.g. VPN, from every “true”/ authorized doctor or medical person

� using a portable device (e.g. USB-Stick) – executed offline

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Zdravko Danailov

Outline

�Introduction�The Telematics infrastructure

�Electronic Health Card

�Health Professional Card

�Hardware Security Module

�Emergency data

�Existing/ proposed solution for Back-up/Recovery of

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Zdravko Danailov

�Existing/ proposed solution for Back-up/Recovery of emergency data�Existing/proposed solution

�Disadvantages�Renewing of the eHC (lost, defect or expired)

�Recovery of emergency data on the eHC

�Krawczyk’s Secret Sharing Scheme

�Our proposal solution

�Conclusion

Conclusion

�Our proposal solution

�minimizes the exposition of privite data

�tolerates no non-availability

�offers better alternatives for back-up and recovery of

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�offers better alternatives for back-up and recovery of emergency data

�uses no encryption but secret sharing

�computationally secure

�information-theoretically unsecure

Thank You!

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Zdravko Danailov

Thank You!