To solve this puzzle, the solver must:
The three decoding steps proceed as follows. In each case, the puzzle provides an example that can be used to confirm if our interpretation of the visual rules is correct.
The diagrams (a bare 3×3 grid and a 12×12 grid with column/row headers) are reminiscent of the diagrams in the X-Ray manual. The arrows coming from the module diagram show how to use the information on the three screens on Page 1:
| Screen | Example | Module | Meaning |
|---|---|---|---|
| Top | GFDURQ | WNKSZV | The encrypted word to be decoded. |
| Middle | Symbols in the (rule-seeded) X-Ray manual. | ||
| Bottom | 1 | 6 | Rule seed to use when looking at the X-Ray manual. |
However, the red bars suggest a slight deviation from normal X-Ray rules. Instead of moving just one step in the indicated direction, the red bars cover a line of six digits. The red boxes on the right suggest to enter those digits there. The decoding instructions then proceed as follows:
| Step | Example | Module |
|---|---|---|
| Open the X-Ray manual of the given rule seed. | X-Ray rule seed 1 | X-Ray rule seed 6 |
| Use the symbols to find a column and row in the 12×12 grid and a direction in the 3×3 grid. | Col 1, Row 9; up-right |
Col 4, Row 7; down-right |
| Obtain 6 numbers in that direction and enter them into the red spaces. | 5 5 2 4 1 3 | 5 1 2 1 3 4 |
| Multiply each number by 2 and add 1. | 11 11 5 9 3 7 | 11 3 5 3 7 9 |
| Enter the encrypted word from the top screen in the next row, converted to numbers. | GFDURQ = 7 6 4 21 18 17 |
WNKSZV = 23 14 11 19 0 24 |
| Multiply the values, modulo 26, then convert back to letters. | 25 14 20 7 2 15 = YNTGBO ✅ |
19 16 3 5 0 8 = SPCEZP |
As indicated by the arrows, the next step involves the keyword on the top screen of Page 2. The visuals represent a step common in the colored ciphers:
The resulting 25-letter alphabet can then be entered into the circles; the dotted lines indicate to use reading order.
The decoding proceeds iteratively for each letter: first obtain the “counterpart” of a letter as indicated by the double-arrows (or keep the letter if there is no arrow), then perform the clockwise rotations of each pentagon.
| Example: Keyword BARNACLE | Module: Keyword SPARROW | ||||||
| Ltr | Decoding | Rotation | Ltr | Decoding | Rotation | ||
|---|---|---|---|---|---|---|---|
| Y | X | S | S | ||||
| N | L | P | P | ||||
| T | T | C | A | ||||
| G | Y | E | Y | ||||
| B | F | Z | I | ||||
| O | V | P | R | ||||
| Example answer: XLTYFV ✅ | Module answer: SPAYIR | ||||||
The table on the left hints at Tap Code (it has the “tap sound” graphics from Tap Code’s module icon, and it indicates that K is missing from the grid). Following the arrows from top to bottom:
| Instruction | Example | Module |
|---|---|---|
| Enter the word from the previous stage into the provided squares. | XLTYFV | SPAYIR |
| Translate the word to Tap Code. | 5 3 3 1 4 4 5 4 2 1 5 1 | 4 3 3 5 1 1 5 4 2 4 4 2 |
| Shift the Tap Code digits as indicated. | 1 5 3 3 1 4 4 5 4 2 1 5 | 2 4 3 3 5 1 1 5 4 2 4 4 |
| Translate the result back from Tap Code. | ENDURE ✅ | INVERT |
We obtain a readable English word — INVERT! After entering this answer into the module, we are greeted with a plot twist. The module doesn’t solve! Instead, it presents a new set of screens. Furthermore, the screens are now black-on-white instead of white-on-black as before! If you’ve ever played Ultimate Cipher, you know what this means: We have to invert the Black Pearl Cipher and decrypt the new given information.
To invert this step, we enter the encrypted word in the bottom of the diagram and work our way up by following the arrows backwards:
| Instruction | Inverted module |
|---|---|
| Enter the word from the top screen on Page 1 at the bottom. | IWBOPN |
| Translate the word to Tap Code. | 2 4 5 2 1 2 3 4 3 5 3 3 |
| Shift the Tap Code digits back as indicated. | 4 5 2 1 2 3 4 3 5 3 3 2 |
| Translate the result back from Tap Code. | UFHSXM |
Think about what would happen if you applied Pentarotation Cipher twice to an encrypted word. We can convince ourselves that the second time around we’d go through the same series of letter diagrams and just change all the letters back to what they were. Therefore, it turns out the inverted version of this cipher is exactly the same and we can just do the forward cipher as before.
If you did not come to this realization, you may also invert the whole process by starting from the 5th rotation (which is the same as the starting diagram), perform counter-clockwise instead of clockwise rotations, and decrypt the letters in reverse order (last to first).
| Inverted module: Keyword BOOTY | |||
| Ltr | Decoding | Rotation | |
|---|---|---|---|
| U | M | ||
| F | Q | ||
| H | X | ||
| S | S | ||
| X | X | ||
| M | U | ||
| Inverted module answer: MQXSXU | |||
We process the symbols the same as before:
| Step | Inverted module |
|---|---|
| Open the X-Ray manual of the given rule seed. | X-Ray rule seed 123456 |
| Use the symbols to find a column and row in the 12×12 grid and a direction in the 3×3 grid. |
= Col 4,
= Row 6; = down-right |
| Obtain 6 numbers in that direction. | 1 3 4 2 5 2 |
| Multiply each number by 2 and add 1. | 3 7 9 5 11 5 |
The last step is considerably less straight-forward. Instead of simply multiplying by the A1Y25Z0 value of each letter, we have to find a letter which, when we do the multiplication and the modulo, will result in the letters from the previous step. This can be done by trying all 26 letters for each equation. (The solution is unique because the odd numbers 3–11 are all coprime to 26.)
| Ltr | Equation | Solution | Ans |
|---|---|---|---|
| M | (3 × ?) % 26 = 13 | ? = 13 | M |
| Q | (7 × ?) % 26 = 17 | ? = 21 | U |
| X | (9 × ?) % 26 = 24 | ? = 20 | T |
| S | (5 × ?) % 26 = 19 | ? = 9 | I |
| X | (11 × ?) % 26 = 24 | ? = 14 | N |
| U | (5 × ?) % 26 = 21 | ? = 25 | Y |
Entering this word into the module disarms it, confirming that it is the solution.
MUTINY