Part of the
World War II Cryptographic Simulation
Japanese Point of View:
Ciphers similar to the one used by our military have been used for
hundreds of years; however, we have adapted ours and change it often enough for it to be
reasonably secure. Each
transmitter is issued three books, one with a dictionary of words and their corresponding
five digit groups. The second and third books are comprised of 50,000 five digit additives that are used to further
encipher the message. In order to encipher the phrase "
I have the honor to inform your excellency" a clerk would first look up each word in the code book:
I = 78130
have = 63450
the = 94025
honor = 57346
to inform = 37694
your = 43791
excellency = 90940
The clerk then looks up a set
position in one of the additive books, and using
non-carrying addition, adds the
additives to the original message. So if the
additives for this day were "61349, 78024, 94613, 75164, 00573, 80861, 17643"
78130 63450 94025 57346 37694 43791 90940
61349 78024 94613 75164 00573 80861 17643
39479 31474 88638 22400 37167 23552 07583
Given sufficient time and a high number of
transmissions, such as our military present, this code can be
cracked eventually. To prevent this we change the
additives books and codebooks on a fairly regular basis.