The AMSO Cipher
The AMSCO Cipher
Oh, I love ciphers. An interesting cipher is AMSCO, and where we create a 5x5 grid with a key. We then lay out our plaintext in a sequence of double and single characters. So let’s find the AMSCO cipher with a key of 41325, for the following:
apessemisticpestexists
We can now layout our key (4, 1, 3, 2 and 5), and then take each of the characters in sequence (with an alternating sequence of 2 then 1, and repeated):
4 1 3 2 5
ap e ss e mi
s ti c pe s
te x is t s
We then read the sequence of the key (1, 2, 3, 4, and 5). And thus is becomes ‘e ti x e pe t ss c is a ps t em i s s’, and so the cipher is ‘etixepetsscisapstemiss’
Did you get that? Well, here is a challenge for you:
For the AMSCO cipher, we take alternative two letter and one letter occurances, and then fit to a grid with a sequence…asecuritysite.com
Now let’s do it in reverse. With a key of ‘32415’, what is the AMSCO plaintext for the ciphertext version of: nwrertht bapng kiereguo? In this we have 21 characters so it will be laid out as:
X X X X X
2 1 2 1 2
1 2 1 2 1
2 1 2 1
First we lay out the key, and then populate the first column:
3 2 4 1 5
n
wr
e
And now the next column:
3 2 4 1 5
r n
th wr
t e
And next:
3 2 4 1 5
ba r n
p th wr
ng t e
And next:
3 2 4 1 5
ba r ki n
p th e wr
ng t re e
And finally:
3 2 4 1 5
ba r ki n gu
p th e wr o
ng t re e
And the result is “barking up the wrong tree”