Encryption

Started by daedalus, November 05, 2019, 06:08:31 am

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daedalus

I have several queries related to encryption :

1) It is my understanding that encryption is only banned for Ham transmissions, there doesn't seem to be any such restriction for the non ham, this opens the door to experiment with encryption methods that could be used after a disaster

2) What encryption method would likely emerge as the dominant standard assuming no internet and therefore no side channel or central repository to pass keys etc

3) How easy would it be to encrypt voice using ham SDR transceiver

wolf

Quote from: daedalus on November 05, 2019, 06:08:31 amI have several queries related to encryption :

1) It is my understanding that encryption is only banned for Ham transmissions, there doesn't seem to be any such restriction for the non ham, this opens the door to experiment with encryption methods that could be used after a disaster

2) What encryption method would likely emerge as the dominant standard assuming no internet and therefore no side channel or central repository to pass keys etc

3) How easy would it be to encrypt voice using ham SDR transceiver

Hi.

ad 1:
Yes, ham radio is due to international regulations experimental and therefore to be in open speech without any encryption.
On comercial (non ham radio) channels you are free to use any encryption method you want.

ad 2:
It's nearly impossible without any preparations in normal times. As we learn from comercial or military applications you have to prepare the ways to encrypt your communication.
No matter what you choose - OTP, openPGP - or any other method you have to exchange relevant information or documents before use.

ad 3:
Use google and you will find a lot of hints. But enc with a HAM-SDR on ham frequencies is not allowed.

gil

Some DMR handheld radios have built-in encryption, like the TYT MD-680.

Gil.

BKM

February 05, 2020, 07:08:21 pm #3 Last Edit: February 05, 2020, 07:13:00 pm by BKM
I don't know about trying to use anything exotic as an encryption method. Isn't the idea of prepping to be able to make your life as easy as possible once you have found the need to activate those skills?

Not that many years ago when I lived in a very different part of the country, our small group was looking for something we could use to encrypt our messages between each other and it needed to be useful across any and all modes of communications. We all agreed that we would use something that might take longer to write down, decode, and then reply in fashion, but that it would have to be simple to understand. So one of the methods we devised was to use a small collection of paperback books that were easy to get and fairly universal as the basis for the code translation table.

I don't remember all of the books right now, but two of them were Dr. Seuss Cat in the Hat, and the other was Hitch hikers guide to the galaxy. Every letter of the message would be represented by a letter followed by 3 numbers. The beginning of the message would indicate the book to use along with the first letter of the message and the first letter of the message must always be from page 1 of the book. So the following message:

B107 would indicate to use Book B (Hitch Hikers Guide) and take the 107th letter from page one to be the first letter of the message.

The only other thing to remember was the letter P. So if the message contained P213 it would not be a letter but an indication to change to page 213 for the next portion of the message.

All other letters in the message would be random letters followed by a 3 digit number. The letters would be ignored and the number would indicate the letter position on the most recent page to be in the decoded message.

So a message like this:

B101 H032 D097 S239 P116 R217 L053 (and so on...)

Would be interpreted as get book B from our reading list and from page one copy letters 101, 32, 97, then change to page 116 and copy letters 217, 053 (and so on...)

This would allow clear speech without encryption and it would just seem like a numbers station. It could also be done with morse code but it might be a bit tiring without some automation. We had other ways to indicate numbers and I don't remember it all right now.

Relying on automated encryption for your secret messages requires that every participant has equally pristine working equipment. Our method meant that you could use and method code you could muster to get the message out as long as you followed the code.

I knew of groups that used the lords prayer, the pledge of allegiance, or a favorite song as long as everyone could remember it. Some used multiple similar sources and rotated them.

Could someone figure out your coding? Yeah, maybe if they were determined and if you gave them enough messages to work from for their decoding task, but it would take a long time. So, Maybe you have multiple methods with multiple sources per method and rotate everything.

I knew of one group that practiced this in the field using a set of old US Army field guide pamphlets that you can find at almost any army surplus store. They were all written back in the 1950's and 60's covering subject from first aid to emergency makeshift shelters. They carried them in their backpacks because they were thin and might not be a suspicious as say The Cat in The Hat!

There are tons of simplistic ideas that are "good enough" for emergency secret comms.

The methods I described above can be universal across handy talkies, cw, or even messages written on paper. The thing to remember is that everyone MUST be able to participate regardless of what equipment they might have functional at the time. Likewise, it must be simple to implement. I remember watching a group of 12 year old explorer scout kids do this using their memorized preparedness pledge as the source and sent the coded signals with semaphore flags!

If you force your mind to work out the simplest possible method to remember and then implement, then you can always come up with something that will work for your group.

But depending on the level of focus you can get from your group, Your mileage may vary!

BKM

2E0WHN

There is a way of using encryption over radio. As long as you are open about what you are using to encrypt and how it is done, then others can use it.

For instance, in the file below you have the Enigma file to be used on a Pringles can. It is available on the internet and as long as you have the start, what reflectors you are using and in which order you are using them in, there is no problem. It may take time for them to decode but you are not hiding the way it is done nor are you making any other and hiding the key.

For instance:

Rotors 1,2,4,5 are used and reflector 1/B. You can put 1245:1/B as your set. Placing the input and output would be a slight problem but you can use the alphabetical ring set so A can be N at the set and keep it there. So you are saying at the beginning 1245:1/B [A.N] So moving all to N the letter A starts at N but finishes up at another letter once the line is followed.

It is a good encryption method but you do have the main body there so you are stating that your rotors, reflectors and settings are known. Yes it will take people time to decode it but you are complying in a way with what you are needing to do with your licence.