introduced digraph reversal in case of same row/column

ip36.py

@@ -83,8 +83,9 @@ def ipfencrypt(msg:str, key:str):
             elif y1 == y2: # same row: get the coords to the right
                 x1 = (x1 + 1) % pfsize
                 x2 = (x2 + 1) % pfsize
-            enc.append(getgridchar(kg, x1, y1))
+            # swap the ciphertext character
             enc.append(getgridchar(kg, x2, y2))
+            enc.append(getgridchar(kg, x1, y1))
     # generate a random prefix
     preflen = (len(key) % 10) + 1
     prefix = ''
@@ -112,14 +113,14 @@ def ipfdecrypt(enc:str, key:str):
             msg.append(getgridchar(kg, x2, y1))
         else:
             if x1 == x2: # same column: get the coords above
-                y1 -= 1
-                if y1 < 0:
-                    y1 += pfsize
+                y2 -= 1
+                if y2 < 0:
+                    y2 += pfsize
             elif y1 == y2: # same row: get the coords to the left
-                x1 -= 1
-                if x1 < 0:
-                    x1 += pfsize
-            msg.append(getgridchar(kg, x1, y1))
+                x2 -= 1
+                if x2 < 0:
+                    x2 += pfsize
+            msg.append(getgridchar(kg, x2, y2))
     # finalize the decrypted message
     return ''.join(msg).strip()