*3.1.1 Authentication schemes*

A total of 515 publications regarding the proposal of authentication schemes were found. Their distribution among the authentication factors is as shown in **Figure 1**. Additionally, the context for which these schemes were proposed was recorded as well; this is presented in **Table 1**, including the publication's origin (journal article, conference article, or book chapter). It is important to mention that only 233 of the publications indicated a context.

#### **Figure 1.**

*Number of publications proposing authentication schemes for every authentication factor.*


**Table 1.**

*Number of publications proposing authentication schemes for every context.*

*Multifactor Authentication Methods: A Framework for Their Comparison and Selection DOI: http://dx.doi.org/10.5772/intechopen.89876*
