Is the answer:
Elaboration based on clues:
Clue 3 and 4:
DRYAD: A paper based cryptosystem used by the US. But, looking into the methods for deciphering a message, it appears that pairs like
BO are invalid since
O cannot be in the second place in the pair (
O do not correspond to any columns in DRYAD cipher sheets). This lead me to research the British alternative BATCO, which ends up working with the given ciphertext and following clues.
Edition No. 819: Thankfully, this one was quite simple, as the sample cipher sheet on the BATCO Wikipedia page was labeled as Edition No. 819. Therefore, I'll be using this sheet to decipher the message.
4 Bravo: This will be the key we will use to decipher the BATCO message. In the topmost row, we find the number
4, then in that column we find the letter
B, which corresponds to
Bravo. The row that this corresponds with will be the row that we will use to decipher the message.
Deciphering the message:
We can see that the pairs of letters found in the ciphertext are also found in the row we found in the above steps. This makes me believe we are on the right track. From here, we go through the row finding the pairs of letters that match with the ciphertext, and find the bolded number in the topmost row and save those numbers for later. The numbers we find end up being
3 1 2 8 3 8 4 5 2 3 7 6 3 3 2 8. We now group these numbers in pairs of two, so the result would be
31 28 38 45 23 76 33 28. With these pairs, we find the corresponding row and column found in the bottom left box in the cipher sheet, with the first number corresponding to the row and the second number corresponding to the column.
31 corresponds to
28 corresponds to
38 corresponds to
T, etc. Continuing this, we get our final result of KETAMINE.