Table 1. Authentication types.

Sr. No	Factor(s)	Initial Parameters	Mutual Authentication	Applicability	Attacks Covered	Vulnerabilities	Threats	Model	Vulnerabilities
1	1FA	User ID & Password	No	Very easy and user friendly	Open Access, Basic Identity	Multiple	Multiple	Simple Login Form	One Time ID/Password may be guessed/cracked
2		Use of Biometric Authentication	No	Difficult, Biometric devices are not available anywhere	Social engineering/dictionary	NO	NO	Finger Print Readers	Online Systems are not matured enough
3		Use of wearable sensors (ECG, EEG)	No	Difficult, Devices are not available anywhere	Social engineering/dictionary	NO	NO	Medical Gadgets	Online Systems are not matured enough
4		Voice signatures	Yes	Difficult, Devices are not available anywhere	Social engineering/dictionary	Voice Signature Reproduction	Yes	Google Voice, Nuance etc.	Recorded data can be reproduced easily
5	2FA	User ID & Password, Email is used for 2FA	Yes	Very easy and user friendly	User Identification & Mutual Authentication	Email Spams	Email may already Compromised	Financial Transactions	If email accountis already compromised
6		User ID & Password, Mobile Phone is used for 2FA	Yes	Very easy and user friendly	User Identification & Mutual Authentication	Smart Phone Vulnerabilities	Phone may already Compromised	Email Services like Gmail	If Mobile Phone is already compromised
7		User ID & Password, USB is used for 2FA	Yes	Very easy and user friendly	User Identification & Mutual Authentication	Smart Phone Vulnerabilities	Phone may already Compromised	Gmail USB Dongle based Authentication Services	What if USB Dongle Got Lost/Cloned
8	3FA	User ID & Password, Email is used for 2FA, Symmetric encryption to avoid spams is incorporated	Yes	Easy, but technically depends on user skill level	User Identification & Mutual Authentication	Key Compromises	–	Custom Build Authentication Frameworks. e.g., WebSeA	If any of the factor source/services are not available
9		User ID & Password, Email is used for 2FA, Asymmetric encryption is incorporated	Yes	Technically depends on user skill level	Non-repudiation	Certificate may Lost	–	Custom Build Authentication Frameworks. e.g., WebSeA	If any of the factor source/services are not available
10	3D	3rd party acts as intermediator	Yes	Requires trust among parties	Non-repudiation	International laws may not be effective		International joint Ventures like VISA and Master	A Central DRU (Dispute Resolution Unit) Acts to resolve the issues
Additional Authentication Factors (AF)
11	4th AF	Geo Location parameter	Yes	Not applicable for indoor activities	–	Services may not be available everywhere	IP Based Location Tracking	EBSCO Services (SANS Patent)	IP Cloning/Spoofing etc.
12	5th AF	Voice signatures	No	Easy, but technically depends on user skill level	–	Recorded data can be reproduced easily	Sound may vary due to weather and may be reproduced	Google Voice, Nuance etc