[Widget] Serial Correlation

[gasp-en]

Note: This is very similar to another proposed widget of "autocorrelation". In fact, this metric is alternatively known as autocorrelation. I make the distinction in name as there still exists differences between this and the more commonly used in cryptographic contexts "Autocorrelation" which more simplistically just counts cooccurences of letters across different lags.

Serial correlation is a test for determining the correlative function of a number of data points across lagged versions of the same data set. For the purpose of interpreting the text as data, characters should be substituted with values based on ascii ordering (A=0, B=1, C=2, etc.). This should simplify to only the characters in the ciphertext (If no B, C=1, etc.)

k = lag/shift
n = total characters in ciphertext
xt = given character
Plot different values for k across a line graph.

More reading: https://en.wikipedia.org/wiki/Autocorrelation