We write the message in a rectangular block, one row at a t ime, and then read off the columns.
To encode the message THIS IS VERY EASY!, write it in a block like this:
THISI SVERY EASY!
The coded message is read by looking at the columns, and writing them out like this: TSE HVA IES SRY IY!
To decode it, just write all the code words in a block again,
as columns, and then read the message across the rows.
LKU OHR OIT KGH WHE IER DRA ELF ROI LOE OKL OFD