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Hello, and welcome to this Instructable. In the following pages, we'll take a look at the basics of the Solitaire cipher, an encryption algorithm created by cryptography specialist Bruce Schneier for Neal Stephenson's novel "Cryptonomicon", a book released in 1999 - 20 years ago already ! It's been designed to use a simple deck of cards to provide high-tech level security.
As some readers among you might be some of my students (I teach in a small suburbian middle-school near Paris) , let me remind you kids that some of the principles behind Solitaire are part of the European Information Literacy and Protection curriculum since 2015, and you will be expected to be familiar with these for your final exams ! Remember that being able to use this cipher could also turn out to be of vital importance for personal information protection.*
*No I didn't go crazy, and I haven't forgotten this is 2008 and not 2019. This Instructable is the first in a series of Instructables related to the Institute for the Future's Alternate Reality Game Superstruct. Set in 2019, this game places players in a world threatened by five major ills - failing and/or hacked communication and computer networks, a severed food chain, devastating climate catastrophes that force populations to migrate, epidemics of Respiratory Distress Syndrom and a world struggling to survive without oil. If you think you're up to the challenge or would like to explore this world more, check the main site and join us !
As some readers among you might be some of my students (I teach in a small suburbian middle-school near Paris) , let me remind you kids that some of the principles behind Solitaire are part of the European Information Literacy and Protection curriculum since 2015, and you will be expected to be familiar with these for your final exams ! Remember that being able to use this cipher could also turn out to be of vital importance for personal information protection.*
*No I didn't go crazy, and I haven't forgotten this is 2008 and not 2019. This Instructable is the first in a series of Instructables related to the Institute for the Future's Alternate Reality Game Superstruct. Set in 2019, this game places players in a world threatened by five major ills - failing and/or hacked communication and computer networks, a severed food chain, devastating climate catastrophes that force populations to migrate, epidemics of Respiratory Distress Syndrom and a world struggling to survive without oil. If you think you're up to the challenge or would like to explore this world more, check the main site and join us !
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Signing UpStep 1Tools you'll need
In order to encrypt data using the Solitaire cipher, you will need the following :
Patience : Encrypting data with the Solitaire cipher takes time. To quote Mr. Schneier, "(Solitaire)'s not fast, though. It can take an evening to encrypt or decrypt a reasonably long message."
Two decks of 54 cards : these decks feature the classic four suits of cards - club, diamonds, hearts and spades - plus two jokers. One of the decks will be used to generate keystream values, the other for backup purposes or communicating to your recipient.
Paper and pencil or a computer terminal : For the purpose of this exercise, any relatively trusted terminal will do. Keep in mind, however, that in a real-life situation you might sometimes not be able to rely on "relatively trusted" hardware. In such situations, all operations should be carried using a disposable writing surface of some sort (only 10 years ago, using paper would have been the easiest option but there are parts of the world where this is no longer the case, alas). Even better, don't write down any information anywhere at all (see my Instructable on methods of loci for more help in that field) - if you can do it all in your head, do so.
Patience : Encrypting data with the Solitaire cipher takes time. To quote Mr. Schneier, "(Solitaire)'s not fast, though. It can take an evening to encrypt or decrypt a reasonably long message."
Two decks of 54 cards : these decks feature the classic four suits of cards - club, diamonds, hearts and spades - plus two jokers. One of the decks will be used to generate keystream values, the other for backup purposes or communicating to your recipient.
Paper and pencil or a computer terminal : For the purpose of this exercise, any relatively trusted terminal will do. Keep in mind, however, that in a real-life situation you might sometimes not be able to rely on "relatively trusted" hardware. In such situations, all operations should be carried using a disposable writing surface of some sort (only 10 years ago, using paper would have been the easiest option but there are parts of the world where this is no longer the case, alas). Even better, don't write down any information anywhere at all (see my Instructable on methods of loci for more help in that field) - if you can do it all in your head, do so.
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There's 2 reasons to that.
1) "Just" shuffling often doesn't add enough "entropy" to the cards sequence - which is why more manipulations are required to increase the overall security of the cipher.
2) These extra manipulations follow specific (and not random) steps so that the person on the other end of the communication line can reverse them and get to the cleartext.
If you have more questions, do go and check the page explaining all about the Solitaire cipher at http://www.schneier.com/solitaire.htm.