Biometric Identity

Solving the Challenge of “Combined” Fingerprints in EBTS 10.0

When the FBI released the EBTS 10.0 specification in 2013, it contained requirements for a number of capabilities which were not yet available on the market. Over time, the biometrics industry and the FBI itself have partnered to meet the high bar set by EBTS 10.0, delivering new functionality and robust standards to end users in the field.

Mobile tenprint enrollments are one area where EBTS 10.0 was significantly ahead of its time. The standard specifically notes that tenprint applicant plain impression (slap or flat) collections—regardless of whether they are generated by fixed or mobile stations—must be generated in a “4-4-2” format.

In other words, to meet the EBTS 10.0 specification, each applicant enrollment record must be collected through two slaps of four fingers each, followed by a slap of both thumbs. This is significantly different than criminal booking or inquiry, in which each arresting enrollment record must be collected through a full tenprint record, consisting of four flats, and ten rolls.

“Combining” is the term used to describe flat fingerprint images which are melded together post-capture to mimic the slap required in a tenprint capture sequence. In a “combined” enrollment, collection occurs through slaps of single fingers or two fingers at a time rather than in the prescribed fashion.

The problem with combining is not that it produces lower-quality images. Rather, the issue is one of sequencing errors. When fingerprints are captured separately, the FBI found that fingers can be taken out of order, leading to sequencing errors.

This dramatically impacts the ability to match prints on the back end—lowering the number of hits and ultimately reducing the value of the fingerprint.

With this in mind, the FBI strictly prohibits combining images in any EBTS records submitted to its database for retention purposes. Official policy is not to accept any combined records—a mantra repeated by FBI officials for years both in public forums and behind closed doors.

In fixed stations, compliance with the EBTS 10.0 guidelines on combined images is easy to comply with. FAP 60 tenprint enrollment devices are plentiful, making it simple to collect a tenprint enrollment.

The same cannot be said, however, in the mobile arena, where available technology has until recently been limited to single finger (FAP 30) or dual finger (FAP 45) devices. Since no company was able to produce a lightweight, pocket-sized four finger (FAP 60) device, mobile tenprint capture remained an elusive goal.

In the absence of mobile technology, which met the specification, agencies turned to the best available options – FAP 45 and FAP 30 devices. While time-consuming to enroll with and technically against the FBI’s wishes, first-generation mobile devices met a pressing need to create and verify identities in the field.

For over a decade, the FBI has grudgingly accepted submissions of combined images from mobile biometric platforms because it knew that effective enforcement of policies was technically impossible.

Now this is set to change. Recent innovations in thin film transistor technology are yielding a new generation of mobile biometric devices which allow for tenprint and 4-4-2 capture on a FAP 60 sized platen.

With the introduction of its Nomad line, Crossmatch will be the first company to deliver a truly mobile tenprint and 4-4-2 device of this size to the market.

Now that technology has caught up to the specification, it will be possible for all agencies submitting to the FBI database to comply with EBTS 10.0 regardless of whether they are using a fixed or mobile platform for enrollment.

This is likely to have two main impacts.

First, the FBI will be empowered to start enforcing its own specification. Rather than turning a blind eye to non-standard field enrollments, the FBI will have new leverage with agencies in the effort to bring all records into compliance. While it is unlikely to start rejecting combined submissions any time soon, the FBI will be able to point agencies to this new generation of mobile devices as refresh cycles loom, or even cause earlier refresh cycles in key agencies.

Second, the desire to submit standard enrollments from the field will likely compel many agencies to replace their single or dual finger biometric devices with new compliant platforms.

This is where the incentives of both the FBI and its partner agencies align–both want the most accurate, least error-prone enrollments possible.

The refresh cycle that results from this new push to meet the EBTS standard will open up an exciting new chapter of innovation in the biometrics industry. As agencies look to meet the spec, they will inevitably bring new mobile use cases and challenges for the industry to work on.

At Crossmatch, we look forward to meeting the evolving needs of agencies in new and creative ways.

Ben Ball is the Government Market Director at Crossmatch, where he oversees market intelligence and strategic outreach to government customers around the world. A ten year veteran of the Federal government, Ben was a Foreign Service Officer and worked in the Department of Homeland Security.

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