OTPC messaging

The holy grail of encoding/spycraft is the One Time Pad Cipher [Wikipedia].

A very simple implementation of a One Time Pad Cipher could be as follows:

1. Anand and Bipasha agree to use a huge block of text as their common source of words.

2. They then assign a numbers (an index) to each word in the text

The above two steps are conducted in secret.

Now, when Anand wants to send a message to Bipasha, he simply replaces every word in his message to her with the corresponding number for that same word from Step 2.

Example

1. Say Bipasha wants to tell Anand this ominous sounding message: "I'm out of state. Remember to describe the scene in detail."

2. Now, say Anand and Bipasha agree to use the following blob of text as their source of words (copied from my own review of a book [Goodreads]).

The Sacred and Profane Love Machine by Iris Murdoch

My rating: 4 of 5 stars

I like racing through books. I'm either in or out when it comes to reading them.

This book, though, was a plodder. It slowed down to a crawl for long stretches when describing a protagonist's inner state. If I remember right, the first actual scene with dialogs in the book comes well past the fiftieth page. By then, I was ready to tear my hair out because I'd had it with the in-depth treatment of every main character's state of being.

That said, the book is for the emotionally aware. The author reflects deeply, and I mean really deeply, into nearly every strand of human emotion. It is a book of great power. It is meant to be read, reflected on, and allowed to ferment in one's subconscious to fully grasp its breadth. I expect that years from now, I will come across something in my life which will remind me of this book.

What sort of observational discipline allows the author to intricately describe every passing detail of behavior, I can't imagine. Yet, here's a book which stands testimony to that brilliance.



View all my reviews

Now, she would encode this message as follows:

006 010 075 037. 040 014 165 161 045 008 168.

Other than Anand and Bipasha, unless they knew the exact contents of the pre-agreed blob of text, no one can make any sense of this OTP message.

The Lede

Can this be turned into a messaging protocol over the internet to prevent snooping by the authorities? I believe it is possible.

All the ingredients are there.

1. Anand and Bipasha merely need to agree on a book - any book in the world will do
2. The protocol ingests this book and keeps it locally on Anand and Bipasha's devices
3. As they write messages to each other in plain language, the protocol converts the message into a stream of numbers as shown above
4. Those numbers are they exchanged over https

Now, even if the authorities demand encryption keys from the service provider, all they will be able to see is this set of numbers which could mean anything they want it mean.

Conclusion

I'm going to build this. Suggestions for improvement welcome.