ATNA Profile FAQ

The Audit Trail and Node Authentication (ATNA) Integration Profile establishes security measures which, together with the Security Policy and Procedures, provide patient information confidentiality, data integrity and user accountability. This environment is considered the Security Domain and can scale from a department, to enterprise or affinity domain

This FAQ answers questions about what this Profile does and how it is used. For FAQs about Implementing the Profile, see the link in the See Also section below.

Why does ATNA only use TLS?

ATNA "Node Authentication" requirements are setting a minimum-interoperability specification. TLS is a mature, well understood, and widely implemented standard that meets the requirements of mutual authentication with optional confidentiality protections.

Why doesn't ATNA use Web-Services Security?

As is stated, the requirements in ATNA are a floor. At this time the best interoperability that provides protections for Confidentiality, Integrity, and Authenticity is through TLS. The Web-Services Security standard have been implemented, but at this time there is poor interoperability. This is the experience of the general industry using Web-Services as well as for healthcare.

The ATNA profile does not restrict an implementation from using Web-Services Security, but does simply require that at a minimum TLS be available.

Why does ATNA require AES?

AES is the replacement standard for 3DES. AES was selected by an extensive encryption standards discovery process in November 2001. It is designed to be harder to break than previous encryption algorithms yet also be appropriate for a wide variety of platforms including very low power embedded systems.

To show this I would like to direct you to a unofficial profiling of the different algorithms done by Michal Trojnara who used OpenSSL to give these Performance Numbers.

Why do we continue to accept 3DES for Connectathon and HIMSS 2007?

Because Microsoft platform (XP, 2000, 2003) has not yet provided the AES algorithm for their TLS implementation. AES is available in the Microsoft Crypto library, but not available in the TLS implementation. AES is available in the TLS implementation in Vista.

How would a Healthcare Provider use ATNA Audit Logging?

• the VHA Audit Profile shows how the VHA plans to use ATNA. July, 2006
• NIST Draft pub 800-92 Guide to Computer Security Log Management

What is Emergency Mode Access and how does it affect Audit Logs?

Emergency mode access is typically used to refer to cases where a clinical professional needs urgent access to information that he/she would not normally have access to. A good discussion of this can be found in an VHA paper on Emergency Access. As this paper points out, Emergency Mode is not an uncontrolled environment. The privilege elevations are well understood and predetermined. Emergency mode can not be used by the janitor to gain access to clinical documents.

The most likely case for Emergency Mode is where a patient has placed privacy restrictions on their records, but an emergency situation (heart attack) for which a restricted clinician is now the only one that can assist. In this case, emergency mode may have previously been defined as allowing this behavior.

Emergency mode is not used by a visiting doctor. The quick provisioning of users should be handled through expedited procedures.

When Emergency Mode is used, audit logging is relied upon more heavily and thus needs to be recorded at the highest fidelity possible. ATNA Includes an Emergency Mode event (DCM 110127 Emergency Override), but does not include the end-of-emergency-mode event. There will be a change proposal on this topic, but in the mean time one should assume that when a user that has declared emergency mode logs out, that the emergency mode has elapsed.

See Also

The ITI Technical Framework is the official master document for this Profile.

The updated version of the Technical Framework with all of the Change Proposals as of Summer 2006 can be found at TF with CPs

For assistance with implementing ATNA see the ATNA FAQ.

DICOM supplement 95 contains MOST of the Audit Trail stuff

RFC 3881 contains the base data model.

AES

This page is based on the Profile FAQ Template