220 likes | 300 Vues
Dynamic system for granting access to health data using digital certificates issued based on a user's access history. Identity and attribute certificates allow for secure and automated authorization decisions.
E N D
CSE5810: Intro to Biomedical Informatics Dynamically Generated Adaptive Credentials for Health Information Exchange EugeneSanzi
Problem • Many stakeholders want easy access to new systems • Physicians need to access patient data, no matter where it may be • Researchers want access to de-identified data repositories • Data may be needed quickly • Emergency medical situations leave little time to gain proper authorization • Systems today still use outdated username/password techniques • Incorrect assumption that physicians have time and ability to register with these systems
Requirements • Need a way for physicians identify themselves to any system • Users possess an electronic ID that they can present for authentication • Provide a method for verifying that presented credentials are legitimate • Allow systems to automatically allow or deny different levels of access based on the presented credentials
SolutionOverview • A physician gains access to different systems over the course of a career • Ex. - Access to their local hospital's data • Access may happen under different roles • Use the physician's system access history as a set of credentials • Each system grants a certificate if access is allowed • Physicians can collect these certificates into a digital wallet and present them as credentials • Systems can see which other systems have granted access
Certificates • Identity certificates are used to establish a user's identity • Public key cryptography is used to ensure that you are communicating with the certificate's owner • Certificates are issued by Certificate Authorities (CAs) • Certificate authorities establish user's identity by other means before issuing a certificate • Ex. Driver's license, SSN • You trust any valid certificate issued by a certificate authority that you trust • Certificate authorities sign the certificates they issue • The user inspects the signature, a valid signature proves it was issued by the certificate authority
AttributeCertificates • A specialized certificate that stores attributes in a key-value pair format • Attribute certificates are signed by an attribute authority rather than a certificate authority • Attribute certificates are connected to an identity certificate • An identity certificate may be tied to multiple attribute certificates • We will use this ability to store information related to user access • Save information on user role assigned by the system
DIRECTProject • Has the concept of a HISP (Health Information Service Provider) • Concept encapsulates systems needed for health exchange • HISPs must maintain their domain and a list of Trusted Anchors • Trusted Anchors are like root certificates • If one certificate in a certificate chain during the certificate validation process is found to be a trusted anchor, the leaf certificate is valid
OIDs • HL7 OIDs are prefixed with the code 2.16.840.1.113883 • There are 3 root branches • The 2 indicates that the root of this branch is managed by JOINT-ISO-ITU-T • Each number represents another branch in a hierarchy • HL7 controls all the children of this code • New OIDs can be generated by registering them with a node's registration authority • HL7 provides a form where new OIDs can be submitted and become part of the HL7 OID standard • A record of the user who submitted the OID is kept on record
Gaining Access • When John Smith wants to obtain access to a new system, he will: • Create a secure connection to the system • Decide which credentials he will send to gain access • Send the relevant identity and attribute certificates along with the request • If access is granted, John Smith will generate a new public/private key pair and receive a new identity and attribute certificate issued by the system's certificate and attribute authority • The system may choose to use a session-scoped Rule Certificate to define John's security policy
DefiningAnAccessPolicy • Each system defines a security policy that specifies constraints based on: • The user role • The type of data being accessed • Valid certificates presented • Provide a mapping from HL7 defined roles to the data that the system guards • Mappings for remote, automatically authenticated users may be different from the mappings given to local users
Example • John Smith wants to access research data on diabetes management from Day Kimball Hospital • He does not have any kind of affiliation with Day Kimball Hospital • He does have his digital wallet of certificates proving his active involvement in the field of medical research
JohnSmith'sNewWallet • John Smith adds the identity and attribute certificates issued to him to his digital wallet • He can now use the certificate issued to him by Day Kimball hospital to gain access to other new systems • Day Kimball Hospital can now identify him with his new identity certificate • John Smith could also make requests for Physician role access using his attribute certificates that name him a physician and the certificates given to him by Day Kimball Hospital
FutureWork • Increase the granularity of security policies • Providers may want to allow/deny access based on location as in Access Control based on Attribute Certificates for Medical Intranet Applications • If a physician is requesting information for a specific patient they have already treated it may help the decision process • May require extension to attribute certificates • Security based on Access Time or Count • Someone who only accessed research data once 20 years ago for a school project should not have automatic access to research data now • Differentiate between certificates issued by an employer and certificates issued in an automatic fashion
FutureWork • Increase efficiency • Validating long certificate chains is a time consuming process • Updates to saved attributes would result in needing to have the Attribute Authority resign attribute certificates • How can a physician regain proper credentials if a CA is compromised? • How to handle local practices which may not have a separation between certificate administration and the medical providers using certificates • Need a method for constraining what local CAs can do