added newline encoding logic

README.md

@@ -32,7 +32,8 @@ the following rules:
 1. The text is converted into lowercase.
 2. Every occurrence of the `0` (zero) character is replaced with the letter `o`.
 3. Every occurrence of either of these characters `_-` is replaced with a space.
-4. Any other characters not belonging to the alphabet are deleted from the text.
+4. Optionally, every newline is replaced with three consequent spaces.
+5. Any other characters not belonging to the alphabet are deleted from the text.
 
 Prior to step 4, the user may apply additional conversions to preserve special
 characters, such as replacing `%` with `cto`, `$` with `dlr` and so on.

ip36.py

@@ -20,7 +20,7 @@ pfsize = int(math.sqrt(len(pfgrid)))
 
 # message/keystring preparation step: replace 0 with o then filter out all invalid chars
 def filtermsg(msg:str):
-    return ''.join(list(filter(lambda i: i in pfgrid, msg.lower().replace('0', 'o'))))
+    return ''.join(list(filter(lambda i: i in pfgrid, msg.lower().replace('0', 'o').replace('\n', '   '))))
 
 # grid keying algorithm
 def keygrid(key:str):
@@ -122,7 +122,7 @@ def ipfdecrypt(enc:str, key:str):
                     x2 += pfsize
             msg.append(getgridchar(kg, x2, y2))
     # finalize the decrypted message
-    return ''.join(msg).strip()
+    return ''.join(msg).replace('   ', '\n').strip()
 
 # entrypoint parameters: [mode] [keystring]
 # modes: e - encrypt with 6x6 IPF, d - decrypt with 6x6 IPF