COM-12 DRYAD Sheet Encryption

COM-12: DRYAD Sheet Encryption

A no-equipment hand cipher for written and courier traffic, and an honest account of what it can and cannot protect.

Why This Course

BLUF: BLUF: Some messages need to stay private from whoever finds them, but do not justify the cost of a one-time pad. This course teaches a grid substitution cipher built on a DRYAD-style sheet: fast by hand, cheap to run, honest about its limits, and kept where the law allows it — on paper and courier traffic, off the air.

By the end of this course, you’ll be able to:

  • Build and size a 36-cell grid substitution cipher on a DRYAD-style sheet
  • Encode and decode a short message by hand, accurately, under time pressure
  • Judge whether a grid is overdue for rotation from its actual use, not just the calendar
  • State which radio rules bar cipher traffic on the air, and where hand-ciphered messages can lawfully go
  • Choose between the grid, a one-time pad, and plain language for a given message

Lessons 01–04

01

The DRYAD Grid as a Substitution Cipher

What the grid cipher protects against and what it does not, the legal lane it lives in, and how to size and randomly generate a grid.

02

Encrypting and Decrypting Text by Hand

Prepare, encode, and decode messages accurately, and catch the slips that quietly produce a plausible wrong message.

03

Key Management for Encryption Use

Distribute one master grid, rotate on the calendar and on volume, and know the four events that force an immediate changeover.

04

Capstone: Field Exercise

Run a timed drill with a planted error, choose the right tool for the traffic, and write the SOP fragment your net will use.

How This Course Works

Format Four self-paced lessons, each with knowledge checks you complete before the next one unlocks.
Time Roughly 20–30 minutes per lesson; the capstone drill is timed at 10 minutes.
Prerequisite None. COM-03 Communications Security (COMSEC) is recommended background.
Materials Paper, a pencil, and two dice or 36 blank cards for the grid-generation exercise.
Certificate Issued once all four lessons are complete, available from the Course Map.

Start the Course →

Fortune Favors the Prepared · Semper Paratus, Semper Gumby · fortunefavorstheprepared.com