You can reach this dialog via the menu entry Crypt/Decrypt \ Symmetric (classic) \ Permutation/Transposition.
This dialog is used to enter the permutations for Encryption by permutation.
In each of the two input fields a keyword or a numerical permutation can be entered. The method for working out the relevant permutation is described under Encryption by permutation.
An entry in the first field is mandatory. An entry in the second input field is optional. If a second entry is made not one but two permutations are performed.
For each permutation it is possible to specify whether the data should be read in/out by row or column. Additionally it is possible to set the permutation to be a permutation of columns or a permutation of rows.
The maximum permutation length is 26. It can be entered either as 26 capital letters or as a number sequence that is a permutation of 1, 2, ..., 26.
By activating the checkbox within the group Options you can determine that before encryption or decryption the input permutations are inverted.
You can get information on the Used permutation and its inverse by clicking the Encrypt or Decrypt button.
Remark:
Historically the permutation exchanging columns twice was called double column transposition.