Reply To: Keys
The Empty Vault › Forums › Bureau of Security and Signals Intelligence Forum › Keys › Reply To: Keys
It’s gonna take the elves forever to moderate, so I might as well explain now.
You probably kept track of the key that decrypts from ciphertext to plaintext. For 3B, that would be
But the key of a substitution cipher is the mixed alphabet that takes you in the other direction: from plaintext to ciphertext.
So you have to invert the key that you found. And here is how to do it.
Put the unmixed ciphertext alphabet in capital letters under the mixed plaintext alphabet in lower-case (the key you found):
Then, move the columns around until the upper row is straightened out. The first column to move is the aW column:
a bopqrstuvwxyzfeghidcjklmn W ABCDEFGHIJKLMNOPQRSTUVXYZ
The bA column is already where it belongs. Next is cT:
abc opqrstuvwxyzfeghidjklmn WAT BCDEFGHIJKLMNOPQRSUVXYZ
When you are done you will have
and you can just see the keyword.