Ciphers Applet

Measuring Avalanche


The linked applet is a sort of a cryptanalyst tool. It allows you to view and even measure the avalanche characteristics of some simple ciphers.
For your convenience, the illustration below shows the layout and purpose of the applet's main controls. More details can be found by clicking on the Help button.

 

While running the applet, note that it can be used in two different modes:

The purpose of the one-run mode is just to help you get the idea of cipher avalanche property. You may want to change any bit or character in the key and/or in the plaintext and view the changes in the ciphertext for different ciphers.

The purpose of the multiple-run mode is to estimate the measures of avalanche for different ciphers. In this mode, you select the cipher and the number of runs for given initial key and the plaintext. (You have an option to set them on your own, or leave default values).

In doing so, run one encryption cycle and store the ciphertext. It will be compared against ciphertexts obtained with a slightly modified key or plaintext. During each subsequent run, only one bit in the original key (or the plaintext) is changed, and the difference in the ciphertext is measured. Then the changed bit is restored, and the next bit is modified for the next run. Statistics collected during the runs are displayed in the bottom window.

Click here to run the applet

Click here to view the source code (the applet class)

Click here to download the whole applet