Dynacrypt® gives its users the option to calculate the Measure of Roughness (MR) for any file that will be encrypted using Dynacrypt®. To find out the Measure of Roughness of the file if encrypted using Dynacrypt® do the following:

1.   Select Open File for Analysis from the File Menu or select the Icon on the DynaTool Bar. A File Browser dialog box will appear as shown below:

2.   Select the file to analyze from the File Browser Dialog Box and select the OK button.

3.   Select Measure of Roughness from the Analysis Menu on the Menu bar or the MoR Icon on the DynaTool Bar.

4.   The Measure of Roughness Dialog Box will appear showing the Measure of Roughness if the file is encrypted.

In designing a cryptographic system, designers try to make their method produce cipher text that approximates as close as possible white or random noise. In the Index of Coincidence (IoC) calculation, this implies having an IoC of .00390625 or 1/256. The Measure of Roughness is another measure that indicates how much individual frequencies of occurrence in the cipher text differ from a flat distribution. A flat distribution of cipher text would have zero variation or a MR = 0.

The Measure of Roughness is defined by

where it is clearly seen that the probability of the cipher text symbol is simply subtracted from the probability of the occurrence of a cipher text symbol in a 256 character ASCII distribution. The squaring of the difference is simply to get a positive result and to prevent unwanted cancellations obscuring the results.

The probability of a cipher text symbol is simply the number of times a particular ASCII symbol appears in a file divided by the total number of characters or symbols in the file. Hence, the sum of all the probabilities in a file is equal to 1. For a flat distribution of cipher text, the probability would be 1/256.