olemus
osa autentimisteabest edastatakse mingi teise kanali
või teise võrgu (näiteks telefonivõrgu) kaudu
= a type of authentication that requires an additional verification through a separate communication channel

ülevaateid
https://www.techopedia.com/definition/29532/out-of-band-authentication-ooba

https://www.onespan.com/topics/out-of-band-authentication

https://slideplayer.com/slide/16471453/

https://doubleoctopus.com/security-wiki/authentication/out-of-band-authentication/

https://crypto.iacr.org/2018/slides/28860.pdf

http://www.wisdom.weizmann.ac.il/~naor/PAPERS/lazy_users.pdf