The EverCrack Language Identification Tools works by calculating the Index of
Coincidence of the cipher text [the Index of Coincidence is a value derived
from frequency analysis that determining the relative distribution of letters
in the cipher text .
Each language has a specific IOC because the letters of each language have a
specific frequency distribution. The IOC value [of the cipher text] is com-
pared to the IOC values of different languages; The language which varies the
least from the IOC value of the cipher text is chosen as the most probable.