Blink

Owner:

Chris Heuser

Solution:

  1. "CHARLESTOWN"

  2. "CHARLESTOWNMA"

  3. "CHARLESTOWNMASSACHUSETTS"

Partial Answers

"MORSE BIRTH TOWN": Keep going

GC Notes:

  • First call: they had all three modifiers identified, but it was late and they partially swapped the blue and green modifiers for their third word, leaving them with "MORSE BIRTH DASE"

    • I asked for a brief overview of what they’d learned so far, and when they mentioned functions for each color I asked them what they knew about each color in turn - verifying yes or no until they’d figured out their mistake.

Presentation:

The team receives a "Morse Encryption Training Kit" panel ("Test Panel"), and a set of three blinking LEDs ("Blinker Panel"):

KIT FA iKÂjÜP C) C) TEST

Test Panel Layout:

  • There are 3 switches on the left. These switches trigger red, green, and blue (in order left to right) LEDs above them when on.

  • There are 4 buttons in the middle, labelled "A", "B", "C", and "D". These buttons turn on a white LED above them when pressed.

    • Pressing multiple times does nothing

  • There is a single button on the right, labelled TEST. When pressed, one of the two LEDs above it will blink out a dot/dash sequence (only one at a time). One is a blacklight LED, and one will blink different colors depending on state.

Blinker Panel Layout:

  • There are 3 LEDs blinking a dot/dash sequence in a loop. From left to right (use color to orient) the LEDs are yellow, cyan, and magenta

Walkthrough:

  • This puzzle is all about encoding and decoding Morse code.

  • When the A/B/C/D buttons are pressed, they add that letter to a sequence that builds up (in the order of press, not left to right).

  • When the TEST button is pressed, one of the two LEDs above the test button will blink out the built-up sequence in Morse code.

  • Pressing a button multiple times per iteration does nothing.

  • The Red, Green, and Blue switches on the left each represent a different encoding that will be applied to the built-up sequence when the TEST button is pressed.

    • Red Encoding: Dots and dashes are swapped for the other symbol - dots become dashes and dashes become dots.

      • "B", for instance, changes from "-…" to ".---"

    • Green Encoding: The character sequence will be reversed, "ACBD" becomes "DBCA" (note this encoding is only noticeable if teams are pressing more than one button when learning the Green switch)

    • Blue Encoding: The dots and dashes in each letter are reversed

      • "B", for instance, changes from "-…" to "…-"

  • When multiple encodings are applied (by turning on multiple switches), they stack (all are applicable without affecting each other, and the order they're applied doesn't matter)

  • When >=1 encodings are applied, the TEST section blinks the sequence on the colored LED by combining the encoding colors.

    • With Red and Green on, for instance, the light will blink Yellow

    • This is Additive Color:

      • Red + Green = Yellow

      • Green + Blue = Cyan

      • Blue + Red = Magenta

  • When no encodings are applied, the TEST section blinks the sequence on the blacklight. (no colors = black)

  • The Blinker Panel is blinking in Yellow, Cyan, and Magenta.

    • The Morse it outputs is nonsense:

      • Yellow: "- --- -.- … .." - "TOKSI"

      • Cyan: "…. - .-. .. …-" - "HTRIV"

      • Magenta: ". … ..- -." - "ESUN"

  • The Yellow LED is encoded using the Red and Green modifiers, and so-on according to color mixing for the others

  • Undoing the encoding on each light gives you:

    • MORSE BIRTH TOWN

    • As the lights are looping, this could be rotated, such as "RSEMO IRTHB WNTO"

COMMON ERRORS:

  • Never noticing that the A/B/C/D buttons produce the characters A, B, C, and D

  • Decoding with two encodings on at a time to match the Blinker Panel lights, thus not having a good understanding of individual encodings

  • Testing with only one character at a time, commonly resulting in missing the Green encoding

  • Not realizing that the looping sequence means they need to look for a rotation at the very end

Hinting:

  • They need to be thinking of their data as dots and dashes, so don't talk to them in terms of letters - ask for dots and dashes

  • Questions to ask (most important in bold):

    • General:

      • "Describe what you've noticed so far"

    • Blinker Panel:

      • "Could you read that data to me?" (ask for dots and dashes if they give you letters)

      • "Have you noticed that the looping sequence means your character sequence might start somewhere else?"

    • Test Panel:

      • "Tell me what you've learned about the Red switch" (encourage thinking about switches individually)

      • "What do you know about the A, B, C, and D buttons in the middle?"

      • "Have you tried pressing multiple buttons before hitting TEST?"

      • "Have you tried pressing buttons in different orders?"

Changes Since Beta/RC:

List changes here so GC staff who played know what's new.

Data:

  • Blinker Panel:

    • Yellow: "- --- -.- … .."

    • Cyan: "…. - .-. .. …-"

    • Magenta: ". … ..- -."

    • (the raw data is TOKSI/HTRIV/ESUN in characters, but don't let them give it to you this way, ask for dots and dashes)

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