New ICAO biometric passport standard adds flexibility

The new method of encoding biometrics in passports that will be required by the International Civil Aviation Organization (ICAO) was examined in depth during the second day of a workshop on “ISO and the New ICAO Passport 2025 Standards” from the European Association for Biometrics (EAB).

Day 1 focused on updates to standards developed by ISO/IEC JTC1 SC37 (Biometrics). Day 2 was moderated by Dr. Uwe Seidel of Bundeskriminalamt and chairman of the New Technologies Working Group at ICAO, and focused on how the changes impact ICAO’s 2025 specifications, which Seidel’s opening slide refers to as “a major step in changing biometrics encoding.”

When Seidel asked 62 participants at a FRONTEX meeting if they were aware of ISO/IEC 39794 and its impact on border control systems, only 22 percent answered affirmatively.

The biometric passport is still a machine-readable travel document with an electronic chip, and the logical data structure is unchanged. Data group 2 and 3, where face and fingerprint biometrics are encoded, respectively, are where the change is found.

ICAO’s Doc 9303 specification currently uses ISO/IEC 19794:2005 for encoding biometrics, but the update will shift to the 39794 standard, Seidel explains. After the update, Doc 9303 will be fast-tracked as ISO/IEC 7501.

All passport inspection devices must support the new data format by January 1, 2026. Passport issuers can use either format from 2026 to 2030, after which they will have to use the new standard. ISO 19794 will be deprecated by 2040.

The changes mean larger facial photos, more meta data, and extensible data records.

Passport manufacturers said that the update would only take about a year, and the volume of data is increasing by less than 5 percent, Seidel says.

Extensibility

R. Rajeshkumar of Auctorizium introduced the ISO 39794-5 Application Profile, which he is the editor of, from the perspective of JTC1 SC17 Working Group 3, which exists to work on travel documents.

While 19794 and 39794 are running in parallel, inspection systems will rely on tags in Table 44, in accord with Doc 9303 part 10. Rajeshkumar also explained the changes to tags and encoding schemes for biometric data in the new specification.

Three types of extensibility are defined in 39794; those without a fallback value, those adding components to choice types, and those with a fallback value.

An interoperability test event, open to all registered members of the travel document community, will be held on October 16 in Sydney, Australia, following a meeting of SC17 WG3.

Olaf Henniger of Fraunhofer IGD followed to talk about the extensible biometric data interchange formats under 39794-1:2019. Part 1 of the standard provides rules for formats that are extensible without invalidating previous structures, and defines common data structures based on the extensibility specifications of ASN.1 (Abstract Syntax Notation One), among several other functions.

Henniger explained the relationship between the standard and the Common Biometric Exchange Formats Framework (CBEFF), and the lessons learned on extensibility from 19794, including that unknown new elements must not cause the system to crash in order to maintain forward compatibility. He also delved into tagged binary encoding and XML format extensibility, as well as the common data structures across 39794 and conformance testing methodology.

Future-proofing biometric identity documents

Dr. Andreas Wolf covered face image data, including the data elements that stakeholders might want to add into passports. These include multiple images, 3D images, quality information, PAD and capture device information.

He also described how several selected data elements are defined by the standard, noting along the way that while some values may not apply to passports (for instance related to facial expression), the standard can be applied to other kinds of documents as well.

Wolf also reviewed the requirements and best practice recommendations for face image enrollment.

Ultimately, Wolf says, implementation of generation three will be easier than generation one.

Anouk Cartrysse of the Netherlands’ National Office for Identity Data says passport issuing authorities a new Dutch passport is planned for 2027. Passports or national ID cards are mandatory for several interactions outside of travelling in the Netherlands, so various relying parties will have to be able to read the new biometric data encoding method, she notes. The same goes for many other countries.

Vendors need to update their systems to allow issuing authorities to move forward, Cartrysse explains, and she is concerned that the planned timeline will not be met without fast action.

Ralph Lessmann of HID Global talked about the forward-compatibility of the 39794 and the importance of well-defined languages.

XML is considered readable by humans, he notes, while ASN.1, which is used for passports, is machine readable.

Lessman covered challenges with enumerations, and why fallbacks are necessary.

Naming conventions, compatibility and format round trips were tested successfully, and Lessman suggests that this shows XML could potentially be used to more easily implement the new encoding in those areas Cartrysse referred to outside of border control.

Evolving biometrics standards back new ICAO passport requirements

Article Topics

biometric passport  |  biometrics  |  border control  |  EAB  |  EAB 2024  |  HID Global  |  ICAO  |  ICAO Passport Standards  |  ISO 39794-5  |  ISO standards