Cronto photoTAN
https://www.onespan.com/ https://www.onespan.com/products/transaction-signing/cronto
https://www.authstrong.com/Solutions-CrontoSign
https://community.onespan.com/products/mobile-security-suite/sdks https://community.onespan.com/documentation/mobile-security-suite/guides/integration-guides/developer/generate-qr-codes-image-generator-sdk
https://www.mn.uio.no/ifi/english/people/aca/josang/publications/aaj2010-icitst.pdf
https://reports.exodus-privacy.eu.org/fr/reports/com.cronto.crontosign.swiss/latest/ https://vie-labs.com/secure-offline-transaction-signing-using-mas/ https://github.com/george-hopkins/caurus https://play.google.com/store/apps/details?id=com.DPMOBESA https://play.google.com/store/apps/details?id=com.vasco.digipass.es
https://github.com/ifad/identikey https://en.wikipedia.org/wiki/Barcode https://github.com/george-hopkins/caurus/tree/master/caurus