OCRA: OATH Challenge-Response Algorithm
D. M'Raihi, Joakim Rydell, Shefali Bajaj, S. Machani, David Naccache · 2011
This document describes the OATH algorithm for challenge-response authentication and signatures. This algorithm is based on the HOTP algorithm [RFC4226] that was introduced by OATH (initiative for Open AuTHentication) [OATH] and submitted as an individual draft to the IETF last year. OCRA: OATH Challenge Response Algorithms September 2006