(upd - 3/23/18) Article - Cipher Security

[TWP]

In past years, we (NNPG) have tried some training on communications cypher coding.  As always, practice is needed.

This is a multi-part article and I will update this post as other parts become available.

Part 1)  https://survivalblog.com/cipher-security-part-1-east-sierra-sage/

Part 2)  https://survivalblog.com/cipher-security-part-2-east-sierra-sage/

In Part 2, there is a PDF link (CypherSecurityi.pdf) which you may want to download and incorporate into your own comm system.  It can be modified to suit your situation.  You will need to read the articles to understand the coding, but it is both compact and "relatively" secure.  Of course you do need to safeguard your version and be ready to change it if becomes compromised/stolen/lost by any member of your group.

[WolfBrother]

I was given a similar code sheet.  I've modified/added to it and have put it in an Excel spreadsheet.
It contains instructions on how to generate a new sheet (the only thing that changes are the row and column heading)

The original was used by a tank Company as a fast way to communicate over a net.   Used in GWI.
They knew the security limitations of using it and their risk evaluation was it was secure enough for use at that time.  ANYONE listening would have to have a number of transmissions, after action reports, and a crypto team working on it.  So the commander said - it's secure enough for right now.

With my spread sheet the term RFNow on one sheet may be H3, the next Z9, the next I5 so it's a bit more secure.
ALSO the Top/left corner - if the instructions are followed - has a unique 2 byte alphanumeric name.