Skip to content

Fortune Favors the Prepared

Semper Paratus, Semper Gumby

Menu
MENUMENU
  • Boomer
    • Day 1 – The Journey Home
    • Day 2 – First Day in the New Home
    • Day 3 – More Training
    • Day 4 – Dad Goes Back to Work
    • Day 5 – A Day at Home with More Training with Dad (Boomer’s version)
    • Day 6 – More Training with Dad at Home
    • Day 7 – Dad Goes Back to Work, Boring Day
  • About
        • The Why
        • Vision and Mission
        • Services
          • Business Resiliency
        • Testimonials
  • Communications
        • Stump Knocker
          • SOI
          • STUMP KNOCKER DMR UPDATES
          • MMDVM Hotspot
        • Family or Group Communications Plans
          • Communications Options
          • Communications P.A.C.E.
          • Communications Resiliency
          • Finding Information for Your Communications Plan
          • Communications Plan Annex
          • SHTF HF Communications
        • Communications Security (COMSEC)
          • Communications Security (COMSEC)
          • Book Cipher
          • One Time Pads (OTP)
          • One Time Pads (OTP) Live Video
          • One Time Pad Training
          • Decrypting One Time Pad Message
        • MESSAGE HANDLING
          • Phonetics
          • Procedure Words (Prowords)
          • Date Time Group (DTG)
          • NTS Radiogram Form
            • ARL Numbered Radiograms
          • Formatted Messages
        • Personal Radio Services
          • FCC Rules for Personal Radio Services
          • Family Radio Service (FRS)
          • General Mobile Radio Service (GMRS)
            • GMRS Repeaters
            • Getting a GMRS License
          • Multi-Use Radio Service (MURS)
        • Other Radio Services
          • Cell Sites and Their Services
          • Radio over LTE and Rapid Radios
          • Communications Continuity Programs and Capabilities
          • Satellite Communications
        • Wired Communications
          • MAG Phone System
        • Baofeng/BTECH Radios Quick Guide
          • Manually Programming a Baofeng Radio – Video
          • A User’s User Manual for Baofeng Radios
        • Digital Mobile Radio (DMR) Networks
          • WR3IRS Interstate DMR Network
            • South Central PA (SC PA)
            • North East PA (NE PA)
            • Washington-Baltimore (W-B)
            • West Central Florida (WCF)
          • Florida Digital Amateur Radio Network (F-DARN)
          • Southeast Florida DMR Repeater Network W2GGI
          • Virginia DMR (DMRVA)
          • NC PRN DMR Network
          • SC Hospital Emergency Amateur Radio Team (SCHEART)
          • HEARS – Hospital Emergency Amateur Radio System
          • New England Digital Emergency Communications Network (NEDECN)
        • DMR Programming
          • DMR Programming – Talk Groups
          • DMR Programming - Roaming
          • MMDVM and Yaesu System Fusion (YSF)
          • Encryption in DMR Radios
        • Amateur (HAM) Radio
          • Why Do I Need a Ham License?
          • How to Obtain Your Amateur Radio License
            • Amateur Radio Learning Resources
            • Finding a Ham Exam
            • HAM Exam Accommodation
            • Getting Into Ham Radio – Video
          • Why You Should Upgrade to a General Ham License
          • What Radio to Buy?
            • What Radio to Buy? – video
            • Live – What Radio to Buy?
          • Ham Radio on a Budget
          • Portable Radio Kit
          • Mobile Communications
          • HF Communications
            • Simple Antenna Builds for HF – video
        • Communications Knowledge Library
          • Communications Resiliency
          • Analog versus Digital
          • CTCSS and DCS
          • Radio Etiquette, Jargon, and Best Practices
          • Are You Expired?
          • Programming Radios with Software
          • AmRRON RESOURCES & REFERENCES
        • COMMUNICATIONS REFERENCES
          • Anytone Programmable Keys
          • Phonetics
          • FRS / GMRS / MURS Frequency Card
          • HAM Simplex Frequency Card
          • CB Frequency Card
          • COMMUNICATIONS RESOURCES – pdf download
  • Insider
  • Blog
    • Mountain Readiness Fallout Workshops
    • Mapping DMR Repeaters
    • COMMUNICATIONS RESILIENCY
    • Getting The Message Through
    • What are you preparing for?
    • Never Let an Opportunity Go To Waste
    • Consequences
    • DO NOT REPLY
    • Space Weather Warning
    • Good, and Sad, News
    • Necessity vs. Luxury
    • Don’t Put off Until Tomorrow
    • No Plan Survives First Contact
    • Threat and Hazard Identification and Risk Assessment (THIRA)
    • Live – What Radio to Buy?
    • Big Daddy Unlimited Affiliate
    • Food – Tue 16th 7pm MST
    • Live from 2021-2-3
    • Live 2021-01-26
    • FLASH SALE
    • Live 2021-01-11
    • What Is Freedom?
    • Preparedness for Pets
    • What If The Lights Go Out?
    • Hoarding or Prepping?
    • Why Do I Need a Ham License?
    • How Bad is the SolarWinds Orion Issue?
    • How To Begin Prepping
    • Members Only Live Videos
    • Live 11/24
    • Ham Radio VoIP Phone
    • Training Calendar
    • A Chat (with some whisky)
    • Blog 2020 11 02
    • Live with Charlie Hogwood
    • EARTH EX 2020
    • A Live with Angery American
    • Have You Woken Up Yet?
    • BUG OUT READY
    • The Gray Man
    • Area Intelligence – Now!
    • Being Prepared for Civil Unrest
    • It Depends
    • The Art of Being Prepared – The New Prepper
    • Get Home versus Bug Out Bags
    • Why You Need an IFAK AND Training
  • Book of Knowledge
        • Threat Assessment
          • Area Intelligence
          • Being Prepared for Civil Unrest
            • Civil Unrest – Area Intelligence
            • Civil Unrest – Be Prepared
            • Civil Unrest – Defense
            • Civil Unrest – Defense (part 2)
          • Weather Awareness
        • Intelligence
          • The Gray Man
          • Community Intelligence
            • Area Intelligence – Now!
          • Operations Security (OPSEC)
          • Signals Intelligence (SIGINT) – the basics
          • Signals Intelligence – Information Gathering Basics
          • Communications Intelligence (COMINT)
            • Short Wave Scanning
            • Communications Continuity Programs and Capabilities
            • State Emergency Capability Using Radio Effectively (Operation SECURE)
            • Integrated Public Alert and Warning System (IPAWS)
          • Electronic Counter-Surveillance
        • Medical
          • Immediate Care – Rapid Assessment
          • Medical Kits
            • Individual First Aid Kit (IFAK)
            • BooBoo and IFAK Kits Video
            • BooBoo & IFAK Kit Mind Map
            • Large Kit
          • Medical Myths
            • Medical Myths – Tampons
            • Medical Myths – Ingested Poisoning
          • MEDICAL REFERENCES
        • Food
          • Why You Should Start a Food Storage Plan
          • Food Storage Quick Start
          • Buying in Bulk
          • FOOD PRESERVATION RESOURCES
        • Power
          • UPS
        • Water
        • Bags etc.
          • Bug Out versus Get Home Bags
          • Get Home Bag – Contents
            • Get Home Bag – video
            • Get Home and Bug Out Bags - video from live 2-10
        • Navigation & Signalling
          • Sketched Strip Map
          • Emergency Signaling
        • Animals
          • Preparedness for Pets
        • Transportation
          • Transportation Plan B
          • Improvised Transportation
          • Preparedness For Winter Travel
  • Planning
        • Family Emergency Plan – The Basics
          • Family Emergency Plan
            • Family Emergency Planning Form
        • Family Contingency Binder
          • Family Contingency Binder MindMap
        • Triggers
          • Preparedness Conditions – PREP-CON
            • Preparedness Conditions (PREP-CON) MindMap
          • Space Weather
        • Inventory Tracking
        • Planning Your Preps
          • Charity in Planning
        • Mutual Assistance Group
  • Resources
        • Training
          • Training Videos
          • One Time Pad (OTP) Exercises
            • 45662
            • 222135ZDEC22
        • MEDICAL REFERENCES
        • COMMUNICATIONS REFERENCES
          • Communications Continuity Programs and Capabilities
        • COMMUNICATIONS RESOURCES – pdf download
        • FOOD PRESERVATION RESOURCES
        • Amateur Radio Learning Resources
        • General Resources
        • AmRRON RESOURCES & REFERENCES
        • Amateur Radio Colorado
          • Colorado Linked Repeater Systems
  • Friends
        • Angery American
        • Signal Stuff
        • Bullets Both Ways
        • Forward Observer
        • Optima Batteries
        • Colorado Ready
        • Patriot Volunteer Examiner (VE) Team
        • The Patriot Outpost
  • Shop
  • Contact
    • Mailing List
Menu

Decrypting One Time Pad Message

The Message

Let me get the legal disclaimer out of the way – remember that it is a violation to transmit any coded message, or a message in any manner that is intended to obscure the meaning, on Amateur Radio (HAM), GMRS, FRS, MURS and even CB frequencies. For the specific rules see this page.

That being said, in Book 11 of Going Home the team sends a message back while they are observing the DHS element.

This is the message you receive (I go into how to create the message on another page as it is quite involved).

The One Time Pad (OTP)

The 1st 5 digits indicate the OTP – in this case 10665. The sender would have chosen one at random from a book, you will have a corresponding book of OTP’s. Once they send their message they will have destroyed that OTP.

You will need to look in your set and find the OTP that starts with the same set of numbers.

You then place the numbers below the numbers you received. BE CAREFUL NOT TO USE THE 1st 5 (you can write them in under the 1st 5 you received, but make sure you are clear that they are not part of the message.

The Math

You then add the numbers in base 10. That is where the number add up to 10 or more you only write down the last digit i.e. if the sum is 11 you write down 1, if the sum is 15 you write down 15. You don’t do anything with the first digit.

The Decoding

You are going to need two additional things to decode the message. One is the code book – a book that is used to take words or phrases and convert them to a 4-digit set of numbers. The main purpose is to shorten the number of digits for the word. A 5-letter word could take up to 10 digits to send it, plus two more to indicate a space (99 indicates a space or 91 for a period). A code word is 1 digit (0) to indicate what follows is a code word, then 4-digits for the word or phrase. As you know it is a code word there is usually no need to include the space (99) after the word. This can considerably shorten the message and can reduce errors in creating the coded message. In the example I didn’t have/use a codeword for MRAP. That took 9-digits to write out including the space characters. With a code word this could have been shortened to 5-digits. It’s now been added to my code book 🙂

Once you have the unencrypted message you then use the code book to translate the codewords and the checkerboard to translate letters and punctuation.

In this example I used a code word for end of message. This allows you to shorten the sent message by finishing with the number set, rather than adding “message ends” in the clear in your transmission. Part of communications security is transmission security – the longer you transmit the easier it is for someone to “DF” (direction find) your location. This is a hobby within ham radio that some folks do, called “fox hunting.”

You will also noticed that there is an “unused” zero at the end. You always complete out a block of 5-digits, so any left over when you create the message are zero’s.

Once you have decoded the message you should destroy the OTP that was used. You should also destroy any paper used to work out the message, i.e., you should use a new sheet to write out the completed message on if you are going to pass that message to someone in your group.

For a more in-depth information on communications security and using one time pads, including encryption, see this page.

Message Authentication

There are a number of different ways to authenticate a message. In book 11 an isogram is used.

An isogram is a word, usually with more than 10-letters, that does not have any repeating letters.

For more on the use of isograms for message authentication see this page.

Please consider supporting content by becoming a Patreon member. It costs $$ for web hosting etc.

Remember, Fortune Favors the Prepared

Semper Paratus, Semper Gumby

Login with Patreon

Login with Patreon

Products

  • BREVITY CARDS FOR ONE-TIME PADS BREVITY CARDS FOR ONE-TIME PADS $24.95
  • Personal Preparedness Assessment Workbook - loose leaf Personal Preparedness Assessment Workbook - loose leaf $24.95
  • Programming Radio Programming Radio $49.95
  • Setup Your MMDVM Setup & Codeplug Setup Your MMDVM Setup & Codeplug $75.00
  • Codeplug development for your AOA Codeplug development for your AOA $249.95
  • Family Emergency Plan Workbook - book format Family Emergency Plan Workbook - book format $24.95
  • Family Emergency Plan Workbook - loose leaf Family Emergency Plan Workbook - loose leaf $24.95
  • Preparedness Mind Map (16x24) 2022 updates Preparedness Mind Map (16x24) 2022 updates $19.95
  • PREP-CON Mind Map (16x24) 2022 version PREP-CON Mind Map (16x24) 2022 version $19.95

Login with Patreon

Login with Patreon

Log In

Login with Patreon

Search Site

Recent Posts

  • Mapping DMR Repeaters
  • Communications Resiliency
  • COMMUNICATIONS RESILIENCY
  • Personal Preparedness Assessment Workbook
  • Getting The Message Through

Site Map

  • About
    • Testimonials
    • The Why
    • Vision and Mission
  • Affiliate Programs
  • Angery American
  • Blog
    • Being Prepared for Civil Unrest
    • Boomer – The Journey
      • Day 1 – The Journey Home
      • Day 2 – First Day in the New Home
      • Day 3 – More Training
      • Day 4 – Dad Goes Back to Work
      • Day 5 – A Day at Home with More Training with Dad (Boomer’s version)
      • Day 6 – More Training with Dad at Home
      • Day 7 – Dad Goes Back to Work, Boring Day
    • Is Ham Radio Dead in California?
    • Live 2021-01-26
    • Members Only Live Videos
    • The Art of Being Prepared – The New Prepper
  • Book of Knowledge
    • Animals
    • Bags etc.
      • Bug Out versus Get Home Bags
      • Get Home and Bug Out Bags
      • Get Home Bag – Contents
      • Get Home Bag – video
    • Communications
      • Amateur (HAM) Radio
        • Amateur Radio Learning Resources
        • Are You Expired?
        • Baofeng/BTECH Radios Quick Guide
          • A User’s User Manual for Baofeng Radios
          • Manually Programming a Baofeng Radio – Video
        • DMR Programming
        • DMR PROGRAMMING – ROAMING
        • DMR Programming – Talk Groups
        • Finding a Ham Exam
          • HAM Exam Accommodation
        • Getting Into Ham Radio – Video
        • Ham Radio on a Budget
        • HF Communications
          • HF Antennas
          • Short Wave Scanning
          • Simple Antenna Builds for HF – video
        • How to Obtain Your Amateur Radio License
        • Mobile Communications
        • Portable Radio Kit
        • What Radio to Buy?
          • What Radio to Buy? – video
        • Why You Should Upgrade to a General Ham License
      • Analog versus Digital
      • Communications Continuity Programs and Capabilities
      • Communications Knowledge Library
        • AmRRON RESOURCES & REFERENCES
        • CTCSS and DCS
        • Radio Etiquette, Jargon, and Best Practices
      • Communications Options
      • Communications P.A.C.E.
      • COMMUNICATIONS REFERENCES
        • Anytone Programmable Keys
        • COMMUNICATIONS RESOURCES – pdf download
        • FRS / GMRS / MURS Frequency Card
      • Communications Resiliency
      • Communications Security (COMSEC)
        • Book Cipher
        • Communications Security (COMSEC)
        • Decrypting One Time Pad Message
        • One Time Pad Training
        • One Time Pads (OTP)
        • One Time Pads (OTP) Live Video
      • Digital Mobile Radio (DMR) Networks
      • DMR UPDATES
      • Encryption in DMR Radios
      • Family or Group Communications Plan – The Basics
        • Communications Plan Annex
        • SHTF HF Communications
      • Finding Information for Your Communications Plan
      • Florida Digital Amateur Radio Network (F-DARN)
      • HEARS – Hospital Emergency Amateur Radio System
      • MESSAGE HANDLING
        • Date Time Group (DTG)
        • Formatted Messages
        • NTS Radiogram Form
          • ARL Numbered Radiograms
        • Phonetics
        • Procedure Words (Prowords)
      • MMDVM and Yaesu System Fusion (YSF)
      • MMDVM Hotspot
      • New England Digital Emergency Communications Network (NEDECN)
      • Other Radio Services
        • Satellite Communications
      • Personal Radio Services
        • Family Radio Service (FRS)
        • FCC Rules for Personal Radio Services
        • General Mobile Radio Service (GMRS)
          • Getting a GMRS License
        • GMRS Repeaters
        • Multi-Use Radio Service (MURS)
      • Phonetics
      • PRN DMR Network
      • Programming Radios with Software
      • Radio over LTE (internet)
      • Radio Services
      • SC Hospital Emergency Amateur Radio Team (SCHEART)
      • Signals Operating Instructions (SOI)
      • Southeast Florida DMR Repeater Network W2GGI
      • Stump Knocker
      • Virginia AWS DMR Network
      • Virginia DMR (DMRVA)
      • Wired Communications
        • MAG Phone System
      • WR3IRS Interstate DMR Network
        • DelMarVa
        • North East PA (NE PA)
        • South Central PA (SC PA)
        • Southern MD (S MD)
        • Washington-Baltimore (W-B)
        • West Central Florida (WCF)
    • Food
      • Buying in Bulk
      • FOOD PRESERVATION RESOURCES
      • Food Storage Quick Start
      • Why You Should Start a Food Storage Plan
    • Intelligence
      • Communications Intelligence (COMINT)
        • Communications Continuity Programs and Capabilities
        • Integrated Public Alert and Warning System (IPAWS)
      • Electronic Counter-Surveillance
      • Operations Security (OPSEC)
      • Signals Intelligence – Information Gathering Basics
      • Signals Intelligence (SIGINT) – the basics
    • Medical
      • Immediate Care – Rapid Assessment
      • Medical Kits
        • BooBoo & IFAK Kit Mind Map
        • BooBoo and IFAK Kits Video
        • Individual First Aid Kit (IFAK)
        • Large Kit
      • Medical Myths
        • Medical Myths – Ingested Poisoning
      • Medical Myths – Tampons
    • Navigation & Signalling
      • Emergency Signaling
      • Sketched Strip Map
    • Planning
      • Family Contingency Binder
        • Family Contingency Binder MindMap
      • Family Emergency Plan – The Basics
        • Family Emergency Plan
          • Family Emergency Planning Form
      • Inventory Tracking
      • Mutual Assistance Group
      • Planning Your Preps
        • Charity in Planning
      • Preparedness Conditions – PREP-CON
      • Preparedness Conditions (PREP-CON) MindMap
      • Triggers
        • Continuity of Government (COGCON)
        • Information Operations Conditions (INFOCON)
        • Space Weather
    • Power
      • UPS
    • Threat Assessment
      • Area Intelligence
        • Civil Unrest – Area Intelligence
        • Civil Unrest – Be Prepared
        • Civil Unrest – Defense
      • Community Intelligence
      • Weather Awareness
    • Transportation
      • Improvised Transportation
      • Preparedness For Winter Travel
      • Transportation Plan B
    • Water
  • Bullets Both Ways
  • CB Frequency Card
  • Cell Sites and Their Services
  • Checkout
  • Civil Unrest – Defense (part 2)
  • Colorado Ready
  • Contact
    • Mailing List
  • Family Emergency Plan Workbook
    • Bug Out Bag & Bins
    • Communications Plan
    • Emergency Evacuation
    • Emergency Food Supplies
    • Family Contingency Binder
    • Get Home Bag
    • Message Drops
    • Miscellaneous
    • P.A.C.E.
    • Rally Points
    • Vehicle Emergency Supplies
  • FRIENDS – AFFILIATES – PARTNERS
  • HAM Simplex Frequency Card
  • Hazard and Capabilities Assessment Workbook
  • Helping You Protect Your Family
  • Insider
  • Mountain Readiness Fallout Workshops
  • My Account
  • My Cart
  • Optima Batteries
  • Patriot Volunteer Examiner (VE) Team
  • Prepping
  • Resources
    • Amateur Radio Colorado
      • Colorado Linked Repeater Systems
    • General Resources
    • MEDICAL REFERENCES
  • Services
    • Business Resiliency
  • Shop
  • Signal Stuff
  • State Emergency Capability Using Radio Effectively (Operation SECURE)
  • The Patriot Outpost
  • Training
    • One Time Pad (OTP) Exercises
      • 45662
    • Training Videos
©2025 Fortune Favors the Prepared | Built using WordPress and Responsive Blogily theme by Superb

PERSONAL PREPAREDNESS ASSESSMENT WORKBOOK NOW IN STORE - bundle with the Family Emergency Plan and use "bundle" discount code. .Get your MMDVM while they are still available. Join Stump Knocker net Monday evenings.