According to some accounts, a significant feature of the cracking of the Enigma Cipher was the realisation that the messages might contain ‘probable words’ (see
The Imitation Game). However, ‘probable words’ has been part of the cryptanalyst’s arsenal for some 500 years, and some early ‘unbreakable’ Vigenère ciphers were very easily cracked in this way. It was this potential weakness when combined with the fact that a letter could not represent itself that provided an opportunity for ‘cribs’ when deciphering Enigma messages.
The point is that if a cipher presents clues as to how it is formulated and the nature of its key then it can be cracked. However, whether this can be done in a timely fashion is another matter. If the objective has been achieved before the cipher is solved then breaking it hardly matters unless there are continuing messages employing exactly the same form.
In the case of Oak Island, one of the keys to breaking the ‘cipher’ is the ground plan underlying the placing of the ground markers (Pit, Rocks, Triangles and Tunnels). The weakness is that these had to be left
in situ and thus provide clues as to identifying one of the keys.
There are other potential weaknesses and one such is providing the key, or a clue to it, in the message itself. One of the Oak Island maps is a case in point. The working of the instructions on Map F is actually illustrated on the map and an instruction in plaintext provides the key to breaking the instructions on other ‘ciphers’ (actually cryptic messages). At the heart of these instructions is the direction, “from centre of triangle between [or betwixt] Rocks 20 feet E,” and this is accompanied by a plan of the Drilled Rocks including a third point.
This completely opens up the instructions on all of the maps, this being, “Identify three points using the ground markers, find the centre of the triangle thus formed and take the specified offset from there.” This enables the map holder to fill in the gaps in the cryptic instructions provided that they know of the existence of the ground markers and can plot them on paper.
Should they hold all of the maps then they will soon appreciate the regular pattern of points that they form in combination. Were it this straightforward then this might suggest that the instructions are simply a short-term contingency measure.
Map point D, lying at top centre of this pattern might be a good place to start. The instructions are widely reported as:
515 SE and by 50 N
36 NE, 36 NE Rocks
3 Feet by 3 Feet by Four.
Harold T. Wilkins reports the first line as reading, ‘515 SE and by 50 N Tree’, which is as it is written on the original map.
Given the ground plan provided in a previous post, and further knowledge of the island, it would be possible to identify what this means. Given that Wilkins’ instructions are correct, there would be a point 50 units of measure south of the Money Pit, which can only be the Welling Triangle which is some 300 feet away, making the unit 6 feet or one fathom.
This would imply that the starting point is 515 fathoms to the northwest of this point, which could only be near the start of the Ancient Roadway which is described in early reports of the island.
Having thus reached the Money Pit (Tree) the instructions carry on (note well, instead of stopping here and suggesting digging) the format implying that the target is mid-way between the Money Pit and one of the Drilled Rocks. As the distance from the Money Pit to the East Rock is 432 feet or 72 fathoms then this would seem to be the Rock indicated.
Assuming that the instruction on Map F to locate the centre of the triangle thus formed also applies to this map, the point identified would have to lie due south of Map point D. The distance to this point can be calculated and proves to be 18 feet. This would then have to be spanned by the instruction ‘3 feet by 3 feet by Four’. The obvious deduction would be that this is ‘3 + 3 + 4 x 3 feet = 18 feet’.
Breaking this cryptic message then facilitates working out the meaning of the instructions on the other maps which identify regularly spaced points on the same design.