X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=szyfrow%2Frailfence.py;fp=szyfrow%2Frailfence.py;h=741e3e2ad3d7bafddbb7d722c468c8103009cb4f;hb=b535d9d75e69cc395e8de28c99e38564655e5ac9;hp=ef3d266f5739ee129d125b5d1d239f57847185aa;hpb=f19a021eabb3222709b9d513839a14c01cfdfd38;p=szyfrow.git

diff --git a/szyfrow/railfence.py b/szyfrow/railfence.py
index ef3d266..741e3e2 100644
--- a/szyfrow/railfence.py
+++ b/szyfrow/railfence.py
@@ -1,3 +1,19 @@
+"""[Railfence transposition cipher](https://en.wikipedia.org/wiki/Rail_fence_cipher).
+
+Works by splitting the text into sections, then reading across them to
+generate the rows in the cipher. The rows are then combined to form the
+ciphertext.
+
+Example: the plaintext "hellotherefriends", with a height of four, written 
+out in the railfence as 
+   h h i
+   etere*
+   lorfns
+   l e d
+(with the * showing the one character to finish the last section). 
+Each 'section' is two columns, but unfolded. In the example, the first
+section is 'hellot'.
+"""
 import math
 from enum import Enum
 from itertools import starmap, zip_longest