IHE Year 4,
the basis for a security solution
Cor Loef
Philips Medical Systems
IHE Planning and Technical Committee
November 2001
IHE InfoRad Theater Session
1
HIMSS / RSNA
Overview
• Why Information Security in Radiology?
• Requirements
• Proposed solution in IHE Year 4
• Is the a reasonable solution?
November 2001
IHE InfoRad Theater Session
2
HIMSS / RSNA
IHE year 4: collection of trusted nodes
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Local authentication of user (Userid, Password)
Authentication of the remote node (digital certificates)
Local access control
Audit trail
Time synchronization
Secure network
System B
System A
Secure domain
Secure domain
November 2001
IHE InfoRad Theater Session
3
HIMSS / RSNA
Selection of standards
• X.509 certificates for node identity and keys
• TCP/IP Transport Layer Security Protocol
(TLS) for node authentication, and optional
encryption
• Reliable Delivery for Syslog (RFC 3195)
• Network Time Protocol ( NTP) for time
synchronization
November 2001
IHE InfoRad Theater Session
4
HIMSS / RSNA
Selection of standards
• Audit trail open issue: events and content
• HL7 Security and Accountability SIG:
Common Audit Message (informative document)
• ASTM PS 115: Provisional Standard Specification
for Audit and Disclosure Logs for Use in Health
Information Systems
• IHE in Technical Framework : Use XML and
vendor DTD for defined content
November 2001
IHE InfoRad Theater Session
5
HIMSS / RSNA
Next level of security
• Full user authentication between nodes, key
management
• Much more functionality and detail in authorization (
role based, patient related ), using central directory
service
• Encryption
• Digital signatures (Reporting function)
• De-identification
• Support for Secure media
• Intrusion Detection Systems
November 2001
IHE InfoRad Theater Session
6
HIMSS / RSNA
Background on RFC-3195
• Reliable replacement for BSD Syslog
• Provides BEEP message structure,
store and forward transport, common
mandatory fields, and an XML payload.
• Options for encryption and signatures.
November 2001
IHE InfoRad Theater Session
7
HIMSS / RSNA
Audit Trail
• RFC - Basic information fields.
• HL7 Security SIG - Information content
recommendations for audit trails.
• Missing component - a DTD
November 2001
IHE InfoRad Theater Session
8
HIMSS / RSNA
DTD
• Joint or separate HL7 and DICOM
DTDs?
• There will be variety vendor DTDs in any real
network
• Audit management will be prepared for multiple
DTDs
• It makes sense for WG 14 to define
DICOM transaction related DTD
November 2001
IHE InfoRad Theater Session
9
HIMSS / RSNA
What level of detail to
describe?
• IHE is recommending routine audit at the
patient level
• C2, CAPP (DoD) require adjustable detail level
» normally high level surveillance
» very detailed for high risk items and for suspect
users
• Is it reasonable to define messages at the
levels:
» patient, study, series, instance, DIMSE
• DTD is prepared for the future beyond IHE
basic support.
November 2001
IHE InfoRad Theater Session
10
HIMSS / RSNA