SPOILERS for Indiana Jones and the Dial of Destiny
According a conversation between Helena Shaw and Indiana Jones regarding the work of the former’s father, Basil, “Archimedes used two codes. Linear B and Polybius Square.”
Linear B is a syllabic script that was used for writing in Mycenaean Greek, and predates the Greek alphabet by several centuries, with Linear B appearing as early as 1400BC. Its full modern deciphering only took place about 15 years before the 1969 setting of Dial of Destiny. It actually remains the only Bronze Age Aegean script to have been deciphered, with its predecessor Linear A, Cypro-Minoan, and Cretan hieroglyphic still to be unravelled.
The other proclaimed Archimedean ‘code’ is much less mysterious. Technically, the Polybius Square is not a code, but the basis for a cypher – the difference being that a code replaces words, phrases, or sentences with groups of letters or numbers, while a cypher rearranges letters or uses substitutes to disguise the message.
Furthermore, despite its name, the ‘Polybius Square’ was not actually devised by the historian himself, although Polybius does state that he ‘perfected’ it (Polybius X.45.6). He instead credits its invention to Cleoxenus and Democleitus.
6 The most recent method, devised by Cleoxenus and Democleitus and perfected by myself, is quite definite and capable of dispatching with accuracy every kind of urgent messages, but in practice it requires care and exact attention. 7 It is as follows: We take the alphabet and divide it into five parts, each consisting of five letters. There is one letter less in the last division, but this makes no practical difference. 8 Each of the two parties who are about to signal to each other must now get ready five tablets and write one division of the alphabet on each tablet, and then come to an agreement that the man who is going to signal is in the first place to raise two torches and wait until the other replies by doing the same (Polybius X.45.6-8).
This device sees the letters of the alphabet – Greek in Polybius’ case (and in the version used in Dial of Destiny) – arranged in columns and rows, which are themselves numbered.
This layout can then be the basis for various cypher shifts; for example, without doing anything extra, each letter of this Latin alphabet Polybius Square now has a coordinate, which (while not an overly complicated cypher to unravel) can provide a rudimentary encryption.
Using this, the seemingly jumble of numbers that is 41421113 4312 41513444423345 can be decrypted to read DIAL OF DESTINY.
There are various methods of using this Polybius Square base to provide more layers of encryption.
We can also work with just the letters in the square, adding a straightforward substitution rule to the encryption, such as a column shift. This would see something like the substituting of each letter in the square for that below it in its column. In this example, the ‘message’ DIAL OF DESTINY becomes IOFQ TL IKXYOSD.
Alternatively, a key word or phrase can be inserted into the square to move the letters around, changing their coordinates – an example here uses the key phrase ‘Polybius Square’, with no repeated letters and all the letters of the phrase placed at the beginning with those not in the phrase added at the end in alphabetical order.
1 | 2 | 3 | 4 | 5 | |
1 | P | O | L | Y | B |
2 | I/J | U | S | Q | A |
3 | R | E | C | D | F |
4 | G | H | K | M | N |
5 | T | V | W | X | Z |
So, going through this ‘key phrase’ addition of encryption DIAL OF DESTINY would come out as 43125231 2153 43233215125441.
Other examples of ways to use the Polybius Square include changing the direction of how to read the coordinates, combinations of the methods mentioned above and putting the resultant letter jumble through the cypher more than once.
It must be said thought that the encryption provided by the Polybius Square are not considered all that secure in the modern cryptology. Using substitution and/or pairs of digits can be broken rather easily through frequency analysis. And in the example of Dial of Destiny, Archimedes must have used a simple version of the encryption offered by the Polybius Square for Helena to just read it off the Grafikos without using a pen and paper to decipher it.
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