Cracking transposition cipher
This looks like a Playfair cipher with MAN as the key.

For characters not in the same row / column, you make a rectangle with the encoded characters at the corners, and the characters in the same row on the opposing sides of the rectangle form the decoded letters. For NP we have -

[N]--B--&gt;C
 F   G   H
 L&lt;--O--[P]


Which yields CL.



So for ET we have -

[E]--F--&gt;G
 K   L   O
 R&lt;--S--[T]


Decoding to GR. 

For KO we need a new rule, since K and O are on the same row. For items on the same row we simply shift each letter left one position, wrapping back to the start of the row if needed. This means KO yields 

I&lt;--[K] L&lt;--[O]


In other words, KO -> IL. 

Finally for KF we have -

 E&lt;--[F]
[K]--&gt;L


Which yields LE

So ET KO KF gives us GRILLE.