24  ODK Biometrics

Author

Chrissy h Roberts

24.1 Biometrics Solutions for ODK Ecosystem Tools

This project provides an Android app Keppel that interfaces with mobile data collection software of the ODK ecosystem and which allows ISO 19794-2 fingerprint templates to be scanned and/or validated as part of an XLSForm. We also provide a second app, the Keppel CLI, a command line interface which is designed to be run on a computer workstation. Keppel CLI can compare two fingerprint templates and return a matching score and is primarily useful for post-hoc quality assurance and audit.

24.2 Validation

This software has been evaluated in a formal scientific context and the results are published in the following study.

Biometric linkage of longitudinally collected electronic case report forms and confirmation of subject identity: an open framework for ODK and related tools
~Chrissy h Roberts, Callum Stott, Marianne Shawe-Taylor, Zain Chaudhry, Sham Lal 1 & Michael Marks
Front Digit Health. 2023 Aug 4:5:1072331. eCollection 2023.~

PMID: 37600479 PMCID: PMC10436742 DOI: 10.3389/fdgth.2023.1072331

24.3 Features

  • Capture to XLSForm one or more enrollment templatesA in an XLSForm

  • Capture to XLSForm a National Institute of Standards and Technology Fingerprint Image Quality (NFIQ) value, a measure of fingerprint quality

  • Scan a verification templateB and compare template to one or more previously saved templates for a known individual

  • Return a match probability score indicating likelihood of their being a match between a verification template and one or more enrollment template.

  • Using XLSform design, constrain form progress, content or actions on basis of both NFIQ and match probability.

  • Depending on form design, capture an identification templateC to scan a modestly sized database of people, in order to identify the current person.

  • Capture to XLSForm the verification or identification templates and verification NFIQ scores

A Enrollment Templates: Created when a user is initially registered in the system. These templates need to be of high quality to ensure reliable future matching. B Verification Templates: Generated when a user attempts to verify their identity. These are compared against enrollment templates for a match. C Identification Templates: Used in systems where one-to-many matching is required, such as law enforcement databases.