Towards a viable and secure health information system - Part 5

This is the fifth and the final of the series of blog posts that I have been writting on the $sbject, inspired by the paper[1].

Let me include the following diagram which illustrates the overall picture on the security requirements of a health information system.

In my previous four posts in this series, I have discussed about Identity Management/Authentication,, Authorization, Auditing and Cryptographic Operations related to the security of health information systems. In this post, I am going to write about another three aspects which are discussed in the paper[1]: de-identification of EMRs for research purposes, user interaction and dispute resolution and security metrics.

5. De-identification

While the EMRs are very useful in medical research as statistics, it should be guaranteed that the records are properly de-identified before disclosing them for research purposes.

Due to the ambiguities in related laws, complexities in de-identifying protected data and the risk involved, the data is rarely shared for research purposes which negatively affect the medical research.

The paper mentions that it is challenging task than implied in the report to develop cryptographic mechanisms to properly anonymize records as required by secondary use considerations.

I need to read about data de-identification before providing my on views on this. However, those techniques should use proper protection against re-identification in order to maintain individuals’ health privacy and build trust in the health care system.

During the research, I came across a description of an interesting research project named "Cloud DNA" [2]. This project is said to investigate on how to enable scientists to share properly de-identified EHRs in the cloud for easy storage, sharing and retrieval.

6.  User Interaction/Dispute Resolution

User Interaction:
Among other factor that we discussed, user interfaces for patients, providers and administrators are eaqully improtant for a secure system.
The paper suggests the following areas to be explored with regard to this aspect:
1. User friendly mechanisms to deal with complexity of user-selected privacy preferences.
2. How much data to make available to patients in what format
3. Techniques for patients to delegate their access rights

Educating the patients on how to use a PHR service or patient's interface of an EMR system is very important aspect in realizing the goal of a widespread health information echo system. While informing them that they have the control of outside access to their records, it is important to highlight that more it is accessible to physicians, better the service they get.

When the patient signs up for a PHR service or a health care provider, he can be presented with a set of easily understandable questions which ultimately defines the access control policies of their medical records.

Dispute resolution
While it needs for patient to have access to and control of their records, should the patients given the right to correct their record? Or else how to resolve disputes on the information in the records? Most administrators do not like this since they can not always trust patients to keep their medical records honestly.
But the patients should be given the chance to raise any dispute against the records in their profile.

The paper illustrated following aspects to be explored with regard to this:
1. Developing way for patients to securely and privately monitor their health records.
2. Allowing ways for patients to dispute the records while preserving original records
3. Coming up with ways to resolve conflicts on the deisputed records

In my view: Patients should have access to all his EMRs and should be able to establish access control over them. But they should not be able to change the medical records as they wish. If there is dispute, or if  a patient suspects a particular report, there should be a way to mark it as suspected immediately - but could only be changed by an authorized medical officer after further tests etc.

7. Security Metrics

Though it is obvious that EMRs have benefits over traditional paper based medical records, there should be proper security metrics to gauge the level of information security/privacy provided by a particular health care information system.

The paper mentions that in order to provide such assessment/analisis, meaningful matrics should be well developed and accepted which opens up research problems on which current work is also going on. Since the domain is limited, the paper believes that matrics can be developed.

Challenges in developpping such metrics are the variety and complexity of threat models and diffculty of measuring potential flaws in Software.

Research problems related to this aspect are:
1. developing threat models covering both electronic and paper based medical records.
2. developing techniques to quantify level of risk associated with sw based health information system

Conclusion:

• I have been writing this series of blog posts about the security, privacy, access control and identity management aspects related to health care IT systems from the  understanding that I got from various sources and my experiences as well. This was mainly inspired by the paper[1] which provides a research road map on the same topic.

• The paper[1] is mainly based on the PCAST report 2010 and this PCAST report have caused some arguments in the field. However, the paper[1] and this blog series has only taken the technical requirements that it has highlighted into consideration to identify the research problems and this blog series doesn't  intend to support or unsupport the report.

• Although the research community has identified and actively working on the research problems pertaining to the subject, there are many obstacles as well, such as difficulty in obtaining testbeds and test data for research  due to the sensitivity and critical nature of the data. Therefore it has been hard for research to comeup with successful results without realistic and live data and also those results obtained from sample mock data are unlikely to be accepted by the community.

• No matter how technically strong the healthcare IT solution is, there should be adequate and non-ambiguous legislation to fully realize the goal of a nation wide health IT echo system.

• During my research on this, I've come across some active and interesting research efforts from some research groups such as Health & Medical Security Lab[3], SHARPS [4] , CERIAS [5], and MediVault [5].

• The paper[1] provides a good overall understanding of the security requirements of a healthcare information system. Most importantly, it provides a very good understanding about the current research problems in the area for a budding researcher who is passionate about carrying out research in security, privacy and access control aspects, outcome of which can be contributed to realize the vision of the secured and viable health IT echo system. 

Related work:
I have done a webinar on Security Patterns with WSO2 ESB for which I picked use cases from health care domain and it was when I first got interested in investigating further on the security, privacy and identity management requirements of healthcare IS. In that effort, I mainly referred MSc thesis on the topic : Security in SOA-Based Healthcare Systems by Richard Sassoon.

References:
[1] A Research Roadmap for Healthcare IT Security inspired by the PCAST Health Information Technology Report
[2] Cloud DNA
[3] Health and Medical Security Lab
[4] SHARPS
[5] CERIAS
[6] MediVault
[7] Security in SOA-Based Healthcare Systems

Towards a viable and secure health information system - Part 4

This is the fourth of the series of blog posts that I have been writting on the subject, which was mainly inspired by the paper[1].

For the clarity and the ease of summarizing, let me include the following diagram which illustrates the overall picture on the security requirements of a health information system.

In my previous three posts in this series, I have discussed about Identity Management/Authentication, Authorization and Auditing. In this post, I am going to write about what role cryptographic techniques play in healthcare IS.

4. Cryptographic Techniques
Confidentiality, integrity and non-repudiation are key security requirements that should be met by any health information system. Encryption, digital signature are the de-facto mechanisms of achieving them. However, traditional encryption mechanisms have major limitations in accomplishing the goals of a distributed, country wide health information echo system.

Let me discuss this further adhering to my usual format: i.e discussing views from the paper[1] and me.

•  As in any security sensitive system, data both at rest and on the wire should be encrypted.
• Traditional public key cryptography has limitations to be used in a health information echo system because of the complexity in exchanging keys used to decrypt the EMRs, among the authorized principals who may come from around the country.
• Therefore, keys used to encrypt the data (we can call this cryptographic authorization as well) are not attached to individuals, but attached to role/identity attributes.
• If encrypted data is stored in one machine, the keys to decrypt should be obtained from  another service which is separately managed.
• The metadata related to EMR(which was discussed in detail in my second post) which contains information about access control to EMRs, should be digitally signed.
• Some of the metadata can be encrypted as well. Since the EMRs should be able to be searched from anywhere in the country, the keys to decrypt the metadata should be known to secure search engines but only the authorized personal should be able to decrypt the actual EMR data.

• The paper highlights the research problems motivated by the above requirements.
• Developing techniques to support flexible key management policies 
• Paper recommends using Attribute Based Encryption (ABE) for cryptographic access control and identifies research problems along that line as:

                  - Developing techniques to specify and enforce access control for EMRs based on ABE
                  - Developing key management solutions for ABE
                  - Provide cryptographic mechanisms to properly anonymize records as required by secondary use considerations such as research.

Here are some of my thoughts on the usage of cryptographic techniques in healthcare information systems

• As the paper suggests, Attribute Based Encryption(ABE) would provide a scalable solution for the cryptographic needs of a health information system and also a solution for the key management requirements.The post[2] describes ABE in detail, in summary what happens is:
  "The plaintext is encrypted with a set of attributes. The KGS(Key Generation Server), which possesses the master key, issues different private keys to users after authenticating the attributes they possess".

• The same post[2] describes two flavors of ABE which are Key Policy - Attribute Based Encryption and Ciphertext Policy Attribute Based Encryption. I believe the second one is more scalable since the keys are issued for the attributes that a principal possesses and whether the given cipher text can or can not be decrypted by that key is determined by the access policy enforced in the cipher text.

• In the paper[4], Akinyele et al. have implemented a solution for self protecting EMRs using Attribute Based Access Control. There, they have used a standard format (CCR) and an automated policy engine which assign a access policy for each record in patients' EMRs using which the records are encrypted with ABE.

• However, there is huge trust placed on Key Generation Server for correctly authenticating and validating the attributes that a user possesses before issuing keys. Therefore necessary actions should be taken in order to prevent it being a central point of failure.

• Performance should also be considered along with security. Public key cryptography is known to posses performance bottlenecks than symmetric key cryptography. However, symmetric key cryptography also has its own limitations. The thesis[3] introduces a symmetric cryptographic approach for key management known as Attribute Based Group Key Management.

Above are based on some of my readings about privacy preserving cryptographic techniques which can be used to accomplish the requirements of healthcare IT systems.

Another area related to the above discussion that I need to explore further is privacy preserving secure searching techniques to make the necessary EMRs available for the authorized physicians when they submit the search query from any location in the country.

References:
[1] A Research Roadmap for Healthcare IT Security inspired by the PCAST Health Information Technology Report
[2] Attribute Based Encryption
[3] Privacy Preserving Access Control for Third Party Data Management Systems
[4] Self-Protecting Electronic Medical Records Using Attribute-Based Encryption

Towards a viable and secure health information system - Part 3

This is the third of the series of blog posts that I have been writting, inspired by the paper[1].

Let me include the following diagram which illustrates the overall picture on the security requirements of a health information system.

In my previous two posts in this series, I have discussed about Identity Management/Authentication and Authorization. In this post, I am going to write about another important aspect of health care IS which is auditing.

3. Auditing

Auditing helps mainly in investigations about frauds or security breaches. In order to recreate an incident, meaningful and useful audit logs should be readily available. Protecting audit log archives is another challenge to be addressed.

Let me discuss this further adhering to my usual format: i.e discussing views from the paper[1] and me.

• The report mentions that the actions like the ones below in a health IT system should be monitored and audited by a security infrastructure which is independently managed.- Actions taken by different principals interacting with the system such as accessing, modifying and deleting EMRs
  - The policies/information used to authorize those actions.
  - Changes to authorization policies.

• It highlights the need of protecting audit logs with cryptographic mechanisms such that they can not be deleted, changed or tampered even by the administrators.

• It also raises the need of facilitating the patients to review audit records pertaining to their EMRs.

• The paper[1] draws attention towards an important concern related to auditing. That is: although it is easy to log every action, it generates lot of volume which causes problems in storage and retrieving info & recreatingan event when an incident occurs.

• Research problems identified by the paper in this space:- Exploring techniques to create audit logs in such a way that we can recreate events as well as limit the amount to store.
  - Finding new approaches for storage and retreival and also user-friendly access to logs.

Let me note down some of my ideas with this regard:

• Distributed logging standards such as XDAS[2] can be used in for auditing at a certain layer in the distributed health IT echosystem.

• Efficient digital signature mechanism needs to be in place for integrity protection of the log.

• Cassandra storage can be used to overcome the issue of large volumes of audit logs and a parallel processing techniques such as MapReduce can be used to efficient processing of audit logs at the retrieval stage. (Cassandra has been used in WSO2 Stratos which is the open source cloud middleware platform offered by WSO2. There, each tenant is able to view logs specific to that particular tenant. Similar techniques can be used to make audit records related to EMRs of a particular patient available to that patient which is a requirement raised in PCAST report as well.)

References:
[1] A Research Roadmap for Healthcare IT Security inspired by the PCAST Health Information Technology Report
[2] Introduction to XDAS

Towards a viable and secure health information system - Part 2

I have started discussing the $subject in my previous post based on a research paper[1] that I happened to read.
This is the second post of the series. Lets again take a look at the following image which summarizes the key considerations with regard to security, privacy and identity management of a healthcare information system.

In my previous post, I have given an overall idea on security in health care IS and discussed the first aspect, which is Identity Management and Authentication.
In this post, I am going to take the second aspect into consideration..

2. Authorization

Since a health information system contains personal information with varying sensitivity, not only authentication is sufficient, but also the rights of the authenticated principals to access certain data should be validated - which we refer as authorization.

For an example, a patient's medical records should only be possible to access by an authenticated principal in the role of a physician and also only during his/her working hours, while clinical data can be accessed by nurses as well. On the other hand, researchers can access medical data only if they are properly de-identified.

There should be proper mechanisms in place to enforce such fine grained authorization.

Let me discuss this in terms of, what the paper[1] analyzes and what my views are, on the mechanisms to accomplish the security requirement of authorization.

• The PCAST report highlights that according to current regulations, it is not necessary to have patients' consent to disclose treatment/payment information in certain conditions. Therefore patients do not have control over privacy of their medical records which affects negatively to build and maintain public's trust in health care IT.

• Mentioning some background information, report advocates the idea of a universal language to exchange health information between different healthcare providers who may still have proprietary formats/schema of storing data. It proposes to use a language structured as individual data elements, together with metadata that provide an annotation for each data element. It can be an extensible markup language, where individual pieces of data can be tagged with context-sensitive metadata.

• Report envisions that such a data representation framework can enable fine grained authorization/privacy preferences where the consent for access each data element (authorization policy) is expressed through meta data attached to it. 

• The paper[1] believes that the data representation framework plays a big role in secured EMR system with fine grained access control, and illustrates how the above recommendations motivates interesting research problems such as:

          - how to programatically tag data based on a particular security/authorization policy

          - how to efffectively feed tagged-data elements to an policy engine to get the decision whether the   requested access is allowed or not.
          - how to efficiently parse and process tagged data elements.

Let me mention some of my views on this aspect:

•  Although I do not have much understanding to comment on meta-data tagged data elements[2], I too strongly believe that there should be fine grained authorization models employed which are also robust, efficient and scalable to achieve the level of privacy that the records in a healthcare IS needs.

• From my understanding about the authorization models used in the identity/privacy world, XACML is a good candidate to implement a fine grained authorization system for healthcare information echo system. It is a policy based mechanisms which is flexible for changing requirements and which facilitates to define fine grained authorization policies based on identity attributes of the principals.Other key attributes of a XACML based solution are: loosely coupled, externalized, centralized and standardized.

• A real world use case example of using a XACML based authorization solution for health care can be found at [3].

• Privacy preserving secure search is an interesting aspect brought to discussion by the PCAST report. Although the search engines aggregate relevant data from multiple providers and provide the result for a search query, engine itself can not see the data which is authorized to be seen only by the certain parties.

• Authorization delegation is another aspect which has not been taken into consideration in the above report and the paper. It is important when physicians and patients use various mobile devices to access EHR and PHR where constrained authorization delegation needs to be performed. Industry standard to accomplish this requirement is OAuth[4].

• I found an interesting research project description [5] which develops an security schema for Veterans Affairs (VA) which claims to provide a secure, manageable, portable, scalable and cost effective solution with fine grained access control in place and which is easily pluggable to the existing system.

In summary:
- Enabling to specify fine grained authorization rules based on privacy preferences and to enforce access control is a key aspect of a secure healthcare information system.
- It should be possible to realize such an authorization model even with existing legacy EMR systems with minimal or no change to the underlying persistent mechanisms.
- One strong mechanism suggested by PCAST report is to use metadata in a tagged data elements framework to achieve this which motivates several research problems.
- Some existing technologies and standards can be used to implement certain aspects of an authorization solution for a health information system such as XACML for fine grained policy based access control and OAuth for authorization delegation.

References:
[1]  A Research Roadmap for Healthcare IT Security inspired by the PCAST Health Information Technology Report
[2] Metadata and Meaningful Use
[3] XACML Sample for Health Care Application
[4] OAuth
[5] Trusted Medical Information System and Health Informatics

Towards a viable and secure health information system - Part 1

IT for HealthCare - Why it is important..

IT has influenced all most all aspects of human life - from education to communication to transport to banking & trading - for the betterment of the respective fields, and healthcare by no means can have an exception.

Large amount of medical records are generated on a daily basis which include patients' medical history, prescriptions, laboratory results, radiology reports, medications etc.

Generating, storing, maintaining and sharing them as electronic medical records (EMR) has many advantages over paper based medical records.
Making a patient's medical records available as EMRs provides easy and fast access from anywhere a patient goes for treatments which reduces cost and risk of repeating harmful diagnosis tests and treatments . It also avoids missing of any critical information regarding the patient's medical history.
EMRs interfaced with PHR (Personal Health Record) Systems provides patients the better access and control over their medical records. Also, EMRs in turn aid insurance claiming processes and providing statistics for medical research which again contributes to advancement of healthcare.

There are many initiatives and lot of research going on to realize the goal of a robust healthcare information system while protecting patients' privacy and security. But no country has yet achieved the  ultimate country wide system - AFAIK.

Concerns in adopting EHR..

Examples for PHR services that have been emerged over the past years are google health and microsoft health vault, to interface with existing EMR systems. Paper at [1] and the article at [2] talks about the issues encountered and solutions applied wrt above two services in a pilot project.

And this article [3] discusses how the non-effective healthcare information system caused discontinuation of Google Health.

Therefore, along with all the advantages, there are technical, political and practical issues in implementing a country wide robust health information system, among which security risks and privacy concerns play a major role since a healthcare system is involved with highly sensitive and critical data. 

Better the access more the advantages and more the security and privacy concerns invloved.

Research problems inspired from those concerns & my views..

I happened to read this interesting paper at [4] which discusses the recommendations made by PCAST (President's Council of Advisor's on Science and Technology) Health Information Technology Report in its chapter 5, based on the identified problems and requirements - in the space of security and privacy - in healthcare IT. 

While some of the recommended solutions in the above report can be addressed with off the shelf solutions, some opens up research problems for the research community.

This paper[1] identifies and expands research problems which are inspired by the recommendations presented in the PCAST report.

Note:  At the final stages of the series of blog posts that I have been writting on this, I found that the PCAST report on which the research paper[4] was based, has caused some arguments in the field. For an example, refer document [5]. However, the purpose of my research and these blog posts is solely to identify research problems in the space of security and identity management in healthcare information system which upon realizing, will cause human advancement, and not to advocate the PCAST report.

The paper[1] is the focus of the series of posts starting with this. There I summarize the main aspects that the paper discusses with regard to security & privacy of healthcare information systems (IS), along with my views and findings on them where applicable.

Before going into detail, following diagram illustrates the main points to be discussed around a secure healthcare IS.

Lets discuss each of the above aspects in detail..

1. Identity Management and Authentication
Lets start with the first aspect which is managing patients' identities and authenticating users in health information systems.

• Each citizen's EMRs need to be mapped with his/her identity in a robust and accurate manner. This becomes more challenging when EMRs for the same patient is generated by multiple healthcare providers. The report highlights the issue of some countries rejecting to have existing physical identities such as national identity number, social security number to uniquely identifying users and mapping EMRs to user identities which may result in issues such as mapping of one patient's EMRs to multiple identities and multiple patients' EMRs to same identity, when reconciling/merging EMRs from different healthcare providers who have used to store EMRs in different formats in legacy storage.

• On the other hand, authenticating users to access EMRs via different mechanisms such as from their PHR applications on the desktops, mobile devices etc is a critical aspect where proper authentication factors needs to be identified to avoid privacy and confidentiality breaches.

• The report identifies authentication factors in three categories: phisycal credentials, biometrics, secrets and suggests that authentication should happen involving at least two of these factors.

• The paper suggests that the obvious solution is to assign a globally unique healthcare identification number to all patients and every healthcare provider, [which of course can have political & technical issues(wrt legacy databases) involved] because without unique id, managing medical records in a large system consisting of multiple providers and many incompatible vendors becomes a problem as discussed above as well.

• As paper identifies, research problems that are inspired by the above discussed requirements and issues include:

          1. developing/improving existing biometric techniqques to identify individuals          

          2. developing techniques to reconcile data from different sources

          3. developing authentication techniques that are less vulnerable to attacks

Let me mention my views on the above aspects based on my knowledge of existing solutions in the domain and my findings about ongoing research efforts in the domain:

• I too strongly agree with the paper's suggestion on assigning a globally unique id to index individual's EMRs.

Regarding identity management and authentication:

• Although different healthcare providers participate in a country wide  healthcare information system, citizen's identity should be maintained with a centralized trusted authority  which we can identify as the identity provider(IdP) in the entire system. This can be considered as provided by national security infrastructure. Thereby we can avoid having duplicated patients' identities in different systems and also multiple credential anti patterns. Individual healthcare service providers can integrate with the central system and act as relying parties to retrieve a particular user's identity information and to rely on getting the users authenticated from the identity provider.

• With that type of interaction between the systems, existing web based authentication mechanisms such as SAML2 Web browser based Single Sign On and OpenID based decentralized Single Sign On can be used to provide users with seamless access to different portals/web applications in the healthcare information system while managing identity and authentication at a single place.

• And if it is a web service of a  third party healthcare service provider that the user needs to authenticate to, brokered authentication mechanisms built on top of WS-Security such as WS-Trust can be used.

• But in this kind of a centralized identity and authentication management  system, authentication at the central identity provider should be performed based on strong authentication factors including biometrics (such as fingerprint which can be supported easily than other biometrics based authentication)  because an attack at the IdP can lead to attacker gaining access to patient's identity and seamless access to other applications to access EMRs and PHRs.

• An example implementation of XMPP based multifactor authentication to avoid phishing attacks on OpenID provider, can be found here. Some research projects have analyzed different authentication mechanisms including biometrics. For eg: "Human Factors in Online Security and Privacy" project[6] in CERIAS has done such analysis.

• Further, when enforcing authentication at the back-end web services which expose different types of EMRs of a patient and which are usually accessed through different user applications (such as web portals, mobile applications, PHR applications etc) by different principals (such as doctors, laboratory scientists, patients etc), it is better to use  mutual  authentication based trusted sub system pattern where only the trusted applications are allowed to access BE services on behalf of the users who were authenticated at the front end applications. This avoids users credentials being propagated to BE services which expose sensitive EMRs  and thereby reduces the risks that can be caused by individual user credentials breaches. By this way, authentication and authorization of the individual users can be performed at two different layers for which I will give an example in a future post.

• In summary, we discussed identity management and authentication aspect of HealthCare IS in detail in this post and it is clear that there should be an agreed unique identity attribute to map patients' records and while there are number of existing solutions that can be used address the issues in this aspect, there are active research in identifying better and stronger authentication mechanisms.

To be continued...

In this post, we only discussed one aspect out of the several aspects illustrated in the above image, related to a secure healthcare information system. We'll discuss about the other aspects explored in the paper at [4], in the coming posts.

Motivation...

I am passionate about the research carried out in the area of healthcare information systems - mainly related to the security and privacy aspects of it, being computer security is the area of my preferred specialization.

And I believe that I have come across a great paper during the research on the $subject.

The paper[1] has successfully achieved its goal of drawing the attention of the security and privacy research community on the problems in health care IT that needs new solutions, based on the requirements and recommendations highlighted in the PCAST report on health information technology.

References:
[1] The military health system’s personal health record pilot with Microsoft HealthVault and Google Health
[2] Personal Health Records In Action: Google Health and Microsoft HealthVault
[3] How a Broken Medical System Killed Google Health
[4]   A Research Roadmap for Healthcare IT Security inspired by the PCAST Health Information Technology Report
[5] PCAST Workgroup Letter to the National Coordinator
[6] Human Factors in Online Security and Privacy