New encoding of biometric data

Following ICAO’s Doc 9303 standard, countries worldwide have started to prepare their travel documents (e.g., passports and identity cards) for a new encoding of biometric data (e.g., face, fingerprints, iris). This means document readers and mobile applications used to scan travel documents will need a software update to be able to ‘read’ this new and the current encoding.

Why should you care?

Systems for identity verification that are not updated (e.g., document readers, mobile applications) will not be able to interpret the biometric data. As a result, they won't be able to show this data nor perform automated identitity verifications.

Technical details*

• New encoding: ISO/IEC 39794-X
• Current encoding: ISO/IEC 19794-X:2005

Background**

Doc 9303 uses ISO/IEC 19794:2005 to encode biometrics. In the new edition of the International Civil Aviation Organization (ICAO) Doc 9303, it is decided to move from using the ISO/IEC 19794 series for encoding biometric reference data to using the ISO/IEC 39794 series for this purpose.

ISO/IEC JTC 1/SC 37 developed the ISO/IEC 39794 series, published in 2019; the third generation of biometric data interchange formats, defining extensible biometric data interchange formats capable of including future extensions in a structured manner.

Current provisions in ICAO Doc 9303 Parts 9 and 10:

• Inspection systems MUST be able to handle ISO/IEC 39794 data by 01-01-2026 after a six-year preparation period starting on 1-1-2020;
• Between 2026 and 2030, Issuing States and Organizations can use the data formats specified in ISO/IEC 19794-X:2005 or in ISO/IEC 39794-X during a four-year transition period. During this transition period, interoperability and conformity testing will be essential; and
• From 01-01-2030 on, Issuing States and Organizations MUST use ISO/IEC 39794-X for encoding biometric data

Current provisions in ICAO Annex 9

• Contracting States issuing eMRTDs shall update their facial image encoding by 1 January 2030 at the latest.

Frequently Asked Questions

Why is it important to change and why can we not just freeze 19794 encoding for issuance/border control?

• In the near future, we will see better quality, i.e., larger portraits, more meta data including quality and security information which can't be encoded in ISO/IEC 19794-X. Additionally, the ISO/IEC 39794-X encoding allows future extensibility of data records.
• ISO SC 37/WG 3, SC 17/WG 3, and ICAO NTWG decided in January 2014 to develop a forward-and backward interoperable encoding in the ISO/IEC 39794 series of biometric data format standards.
• The data formats ISO/IEC 39794-1 (framework), ISO/IEC 39794-4 (finger image), and ISO/IEC 39794-5 (face image) have been published in December 2019.
• The binding deadline is 2040, when ISO/IEC 19794-X will be no longer available: Having in mind that many passports are valid for ten years, until 2030 all newly issued documents should be compliant to ISO/IEC 39794-X to ensure that during the circulation of ISO/IEC 19794-X passports the relevant standards are still available and valid.

Issuance: How long will it take to change the encoding in the issuance process at manufacturers?

• The modification should not take more time than usual for a document development process. The standard ISO/IEC 39794-4 has been published in December 2019; a 12-month project was estimated as realistic.
• However, the transition is more challenging compared to the PACE-only change since the personalization according to 39794 is not yet implemented:
  • In contrast to the access control protocols, which could exist in parallel, we unfortunately cannot issue passports which cover both biometric encodings.
  • In order to limit unexpected behavior of passports issued according to the new standard a staged approach (as for the introduction of PACE-only passports) is suggested:
    • After initial interoperability trials, sample documents with the new encoding could be produced and distributed through NTWG (or other channels) for testing.
    • If these do not show any  issues during inspection, the final transition could be started.

Issuance: Possible impact on data size, chip hardware, enrolment?

• Data size: TLV (Tag-Length-Value) encoding as before, main payload is facial image (and two fingerprints for the EU) as before. Due to some extra meta data, a size increase of < 5% is estimated.
• Chip hardware: The storage capacity of the chips currently in use is considered sufficient.
• Enrolment: The new standard offers more possibilities to record (optional) metadata.

Inspection systems: Possible impact on systems, read times, backward compatibility?

• Inspection systems: Changes have to be implemented in readers and possibly in border control systems. The impact depends on the flexibility of the reader’s API.
• Reading/Verifying data: No impact –data size marginally increases, no impact on Passive Authentication.
• Backward compatibility:
  • The primary target of the ISO/IEC 39794-X development was to allow forward and backward compatibility. During the transition period, inspection systems need to be able to read ISO/IEC 19794-X and ISO/IEC 39794-X data records.
  • ISO/IEC 39794 is not backward compatible with ISO/IEC 19794.

More about all ICAO publications, go to ICAO.int

* Travel documents containing current and new encoding are expected to be in circulation between January 1st 2026 > January 1st 2040 (approximately).

** Source used: Seidel, U. (2024) EAB Workshop on "ISO and the New ICAO Passport 2025 Standards”