text:
Cookbook talk:Recipes

en:User:Angela and I are Transwiking wikipedia recipes into the Transwiki psudonamespace. If someone wants to go through the transwiki log and work on those articles and bring them to Wikibooks standards, feel free. It'll add more content to the cookbook faster, as right now I'm going to concentrate on moving the pages out of wikipedia. Thanks, Gentgeen 09:49, 23 Jan 2004 (UTC)

OK, we need to come to a naming convention for recipes. I've been using Cookbook:, others are using Cookbook:Recipes/ or Cookbook:Recipes/. It'll be easier to pick a standard now and just name things as we move them from wikipedia than it will be to decide later. Anyone else want to weigh in? Gentgeen 09:11, 29 Jan 2004 (UTC)

 * OK, I'm going to give this a week and if no one replies, I'll assume I'm the only one here and just pick my standard and start moving recipes to Cookbook:Recipe Name . Time starts .... NOW Gentgeen 08:44, 3 Feb 2004 (UTC)

 * Personally I like your system. It's simpler. Also I can see a situation where we need subpages for recipes cookbook:recipe Name /european verion that soer of thing. Theresa knott 09:03, 3 Feb 2004 (UTC)

 * Yes, I started the Cookbook:recipies/* standard just to be descriptive and it the Cookbook:* standard does seem like a better idea. Grimm

kinds of sugar
Query: Does anyone know what "Castor sugar" is? Is it a brand name or a type of sugar? As long as I'm at it I may as well make a list on this page of questionable ingrediants. Grimm
 * I guess it's a British thing? Castor sugar is a very fine sugar.  You can make it by putting regular granulated sugar in a blender for a few seconds to make the grains finer. Solitaire
 * That is somewhat correct. Probaly you'll wear out your blender if you abuse it for this purpose! Castor sugar is called superfine sugar in the USA. Unfortunately, castor sugar is the default sugar in the UK. Many recipes specify it needlessly. As each such recipe is examined, "castor sugar" should be replaced with either "superfine suger" (to indicate a true need for superfine sugar) or just "sugar" (to indicate that any old normal sugar will do). AlbertCahalan 19:38, 5 Apr 2005 (UTC)

 * Castor sugar is not the default sugar in the U.K. but it is used more frequently than in the United States because it is much more commonplace there. It is called "castor sugar" because it is fine enough to be used in a "caster" which is a "shaker". Mike Hayes (talk) 03:02, 19 August 2008 (UTC)

 * 'golden syrup' - Cane Syrup

 * I'm sorry - I have to jump up and down and scream loudly at this comparison. Golden syrup is NOT corn syrup or anything remotely like it. It's a product used mainly in Australia (I don't know if it's available anywhere else...) It is a bit like molasses or treacle only lighter in flavour and consistency. Corn syrup is NOT a suitable substitute for it.KJ 06:46, 19 Mar 2004 (UTC)

 * we have stuff here in the US called Cane Syrup, made from sugar cane, kinda like a light molasses. Would that be a better compairason to golden syrup? Gentgeen

 * Oh lord this is going to be a nightmare. I asked an american once what corn syrup was and was told it was golden syrup, I didn't check to see it was correct. On wikipedia there is an article on flapjacks, which redirects to pancakes. In the UK flapjacks are oatcakes made with rolled oats, butter amd golden syrup :-( why can't we all speak the same laguage :-( Anyway, I digress. In the UK golden syrup is made by Tate and Lyle. Since this company also label their granulated sugar as cane sugar I assume cane syrup is correct. Sorry about not checking my facts properly. Theresa knott 11:18, 19 Mar 2004 (UTC)

 * "Tate and Lyle's Golden Syrup" has a pronounced flavour unlike anything generally available in the United States but maple syrup or imitation maple syrup would work well as a substitute. However, it tends to be thinner than golden syrup so one would have to reduce it by boiling to get a similar viscosity. Mike Hayes (talk) 03:02, 19 August 2008 (UTC)

 * 'Castor sugar' - Like granulated sugar only smaller crystals so it dissolves better - so it's like the US baking sugar or bar sugar? gent
 * Castor Sugar is a very finely ground sugar. You can use plain ordinary sugar in a recipe without a problem except the texture will be coarser.KJ 06:46, 19 Mar 2004 (UTC)
 * I'm in the US, and sometimes I use "powdered sugar" -- like granulated sugar, but ground into a fine powder. http://sugarindia.com/ has some descriptions of various kinds of sugars. --DavidCary 18:05, 29 Oct 2004 (UTC)

Tate & Lyle's Golden Syrup is, I quote from the tin, "partially inverted refiners syrup", (that is, some of the sucrose is laevo-rotated, for the chemists out there) & is commonly called treacle in the UK. Black treacle is the dark stuff like mollasses. Granulated sugar is your bog-standard sugar, castor sugar is finer, (for using in a caster?) & icing sugar is (very fine, floury), I think, powderd sugar in US. We use it to make icing, (frosting) by mixing with water (& eggwhite for Royal Icing). Hope this is useful, & please correct me where im wrong--Archolman 02:46, 6 March 2007 (UTC)

other ingredients

 * "375g of packet fresh ready rolled Puff pastry" (see Cookbook:Mille_Cr%C3%AApe) - Any ideas on a universal equivilant? why not just link to a recipe for puff pastry? - whenever I use puff pastry, I go to the store and buy a box. Actually, I normally have a box or two in the freezer.  Making puff pastry is hard, time consuming, work, and I'd rather pay Pillsbury to do it. gent
 * Frozen puff pastry is available just about everywhere... I don't see that direction as unreasonable wherever you are. But for perfectionists, link it to 'puff pastry' too so they can see how difficult it is to make from scratch! lol KJ 06:46, 19 Mar 2004 (UTC)

 * "2 small cans dry Mustard" (see Cookbook:Senf) well, what's a small can? 1 oz, 4 oz? ( I've seen some cookbooks list *both* Imperial *and* SI units on each and every recipe. Should we encourage this ? Something like  "50 g (1.7 oz.) dry ground Mustard". At least in one cookbook, the primary units were the ones used by the cook who submitted it. Usually ounces for U.S. chefs, grams for French chefs. The secondary units (in parenthesis) were converted. --DavidCary 18:05, 29 Oct 2004 (UTC) )

 * I'd say we should definitely encourage the use of both imperical and SI units. I've even gone through a few recipies that only have one set of units listed and done the conversions myself when I have too much free time. Grimm
 * Be very careful! Tablespoons can be 15 mL (Queen Anne), 18 mL (Imperial), or 20 mL (Australian). If you are unsure, let someone else do the conversion. AlbertCahalan 19:38, 5 Apr 2005 (UTC)

Looks like some redirects are in order, once we've got the basic foodstuff articles written. For the life of me I couldn't figure out what golden syrup or Castor sugar were, thanks Theresa. Gentgeen 00:46, 19 Mar 2004 (UTC)

I did suggest that we need a 'glossary' page giving comparisons and equivelants like this. It's easy to get confused, because cooking is universal but ingredients are NOT... KJ 06:46, 19 Mar 2004 (UTC)

 * I started a list of International food terms. I listed US/UK terms, as that is what I'm familiar with.  I'm not sure if the UK terms are pretty much always the same as the Australian terms, and I could lump them together, or if there should be a separate column for Australian terms.

 * I added it to the Ingredients section on the Cookbook, along with the Substitutions list I started, although perhaps there's a better place for them. -- loum 04:19, 24 May 2004 (UTC)

The UK standard spoons are; Tspoon=5ml, Tablespoon=15ml. i think cup sizes are a bit different to US & Aus. as well:)--Dick 23:13, 16 March 2007 (UTC)

Featured recipes
So far, I've just picked a recipe from this list about once a week to be our featured recipe on the cookbook page. Anyone else want to get in on choosing the recipe? (and ingredient, but that discussion should go somewhere else) Gentgeen 00:46, 19 Mar 2004 (UTC)

Recipe cleanup?
A few of the recipes need some work. For example, look at Goulash, Jamaican Jerk Chicken, and How to cook oysters. Should we have a central page for these types of cleanup items for the entire wikibooks project, one just for the cookbook, or just use, for example, this talk page to hold this list. Gentgeen 08:57, 4 May 2004 (UTC)
 * I would say create a link on the cookbook main page that refers to the "Needs Work" recipes. liblamb 16:48, 12 Jul 2004 (UTC)

links to GFDL and public domain recipes
Should I copy-and-paste these recipes to wiki, even though I've never cooked them before ?

 * http://www.faqs.org/docs/consumer/recipes/ (public domain)
 * The Open Source Cookbook: Fuel For Geeks by Matthew Balmer (GFDL) http://www.faqs.org/docs/cookbook/
 * this cookbook is GFDL 1.1, and contains front cover, back cover, and invariant texts. All these things make importing sections from this book difficult under our use of this license.  I think discussion of this cookbook was brought up earlier at Talk:Cookbook. Gentgeen 21:13, 29 Oct 2004 (UTC)

"Copyright and Recipes" http://www.recipezaar.com/help/copyright.zsp

 * I have no objections to you doing this. If you do place them in Wikibooks, please make them conform to the template.  You might also want to be selective.  I have entered a number of recipes, one of which is Hominy, that I considered of interest but have not cooked. liblamb 20:00, 29 Oct 2004 (UTC)

Some recipes aren't linked here
I've been searching for curry chiekn, but I just found when i find it, that its not listed here, in the recipe index!! Can someone merge these "lost recipes" please?

Here's some:

Cookbook:Meat_Recipes
 * Done liblamb 17:39, 3 Dec 2004 (UTC)

Yeah, I've been finding lots of "lost" recipes the past few days. Grimm

Recipe Overviews
My wikisyntax is limited, but would it be easy to make a template out of the Overviews? Also, if I think someone should link to a recipe with what may be considered the ideal format so people adding them have a good template to start with.

Cheers, --bleh fu talk fu  15:49, 25 Jun 2005 (UTC)

Conversation from #wikibooks IRC Channel
I have bought this conversation and idea here, from #wikibooks, and also from Cookbook Talk, in the hope that I may be able to help. I am on multiple restricted diets, being intolerant of Gluten and Lactose, so I am on a Wheat/Gluten Free and Milk Free diet. One of WB's admins, Uncle G, has informed me that your recipes are marked for which diets they are suitable. However, I have noticed looking through the index of recipes that there is no immediate identification of suitability for particular diets there. I also feel that for meals which cross diets, ie, one which is both Gluten Free and Milk Free, having to match recipes from one category and see that they are in another is time consuming.

What I have proposed is that we look at a simple identification tag to attach to recipes in the index, to show immediately to the searcher that the meal is gonna be suitable for them to cook.

Something along these lines:

GF indicates Gluten Free recipe

MF = Milk Free

LF = Lactose Free

RS = Reduced Sodium (Salt)

which could be combined to show the suitability immediately, like:

Liver & Bacon Casserole (GF : MF)

or for meals which are suitable for diabetics, DS.

Your thoughts on this are welcome, and I have tagged some pages already pointing people here to discuss this proposal. I can be contacted here, or thru my Wikipedia talk page, Talk to Thor. Regards, Tmalmjursson 01:42, 1 February 2006 (UTC)

is this still maintained?
wouldn't the category system be a better option? Especially for indicating whether recipes have images or not... 203.214.115.130 14:32, 24 April 2006 (UTC)

 * Yes the category system is better. Category:Recipes will probably be better even at this stage of categorization. It will also be more maintainable over the long run. Kellen T 00:24, 1 May 2006 (UTC)

Sindhi cuisine
There were some recipes on the Wikipedia page Sindhi food. The article's AfD determined that the recipes should be transwikied here. I've put them on a subpage here, and anyone interested can copy them from there and place them appropriately at Wikibooks Cookbook. I'd appreciate help from someone who knows what they're doing here. Thanks! (I also posted this message at Cookbook talk:Cuisine of India.) --Fang Aili 23:29, 24 April 2006 (UTC)

Moving and Deleting
Hello! This page is becoming deprecated as Category:Recipes is more complete and automatically updated/sorted. Having a second, less complete index doesn't make much sense, and previous threads have acknowledged this. As a result, I am planning to make sure every recipe listed here is correctly categorized as a recipe before removing it and ultimately redirecting this page to Category:Recipes. Hopefully this will help clean up the cookbook. Cheers! —Kittycataclysm (discuss • contribs) 22:23, 5 January 2023 (UTC)

title: Cookbook talk:Recipes


text:
User:Tompagenet

This is Tom Page's section on the great project that is WikiBooks. A couple of (hopefully) useful links:

 * My wikipedia page
 * My personal web page

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User:Tompagenet


text:
Cryptography

Welcome to Cryptography, the study of obfuscating data to unintended recipients.

Part I: Introducing Cryptography
 * 1) Introduction to Cryptography
 * 2) History of Cryptography
 * 3) Classical Cryptography
 * 4) Contemporary Cryptography
 * 5) Cryptography in Popular Culture
 * 6) Quantum Cryptography
 * 7) Timeline of Notable Events
 * 8) Fundamental Concepts
 * 9) Goals of Cryptography
 * 10) Goals of Cryptanalysis
 * 11) Role of Cryptography in Computer Security
 * 12) Symmetric Key Ciphers
 * 13) Asymmetric Key Ciphers
 * 14) Random Number Generation
 * 15) Hashes
 * 16) Key Distribution and Authentication (key management and the web of trust)
 * 17) Common flaws and weaknesses
 * 18) Secure Passwords
 * 19) /S-box/

Part II: Designing Crypto-systems
 * 1) The Basic Principles
 * 2) Little Secrets Hide Bigger Secrets
 * 3) Open Algorithms and the Value of Peer-Review
 * 4) Think Like a Cryptanalyst
 * 5) Cryptography/Error Correction Systems
 * 6) Mathematical Background
 * 7) Computer Security is More Than Encryption
 * 8) Unbroken is Not Necessarily Unbreakable

Part III: Cryptanalysis
 * 1) The Basic Principles
 * 2) Weaknesses
 * 3) Proportionality of Secrecy
 * 4) Length of the key
 * 5) Quality of Random Source
 * 6) Plaintext effect on Ciphertext
 * 7) Statistical Leaking
 * 8) Faulty Implementation
 * 9) Inadequate Peer-Review
 * 10) Social Engineering and Coercion
 * 11) Leakage and Side Channels
 * 12) Attacks
 * 13) Brute-Force Attack
 * 14) Dictionary Attack
 * 15) Frequency Analysis
 * 16) Index of Coincidence
 * 17) Linear Cryptanalysis
 * 18) Differential Cryptanalysis
 * 19) Meet in the Middle Attack
 * 20) /Man-in-the-middle attack/
 * 21) /Breaking Hash Algorithms/
 * 22) Collisions
 * 23) Generating
 * 24) Exploiting
 * 25) Birthday Attack
 * 26) Joux Attack
 * 27) Time Memory Trade Off (rainbow tables)
 * 28) How Historical Systems Were Broken
 * 29) Transposition Ciphers
 * 30) Caesar Cipher
 * 31) Enigma Machine
 * 32) Permutation Cipher
 * 33) Vigenère Cipher

Part IV: Using Cryptosystems
 * 1) Applying Cryptography
 * 2) Digital Signatures
 * 3) Introduction to Digital Signatures
 * 4) DSA
 * 5) Database protection
 * 6) E-Cash
 * 7) E-Voting
 * 8) DRM
 * 9) Biometrics
 * 10) Anonymity
 * 11) Classical Ciphers
 * 12) Beale Cipher
 * 13) Transposition Ciphers
 * 14) /Caesar cipher/
 * 15) Atbash Cipher
 * 16) /Autokey cipher/
 * 17) Playfair Cipher
 * 18) /Polyalphabetic substitution/
 * 19) Scytale
 * 20) /Substitution cipher/
 * 21) /nomenclator/
 * 22) Permutation Cipher
 * 23) /Affine cipher/
 * 24) /Vigenère cipher/
 * 25) /Polybius square/
 * 26) /ADFGVX cipher/
 * 27) /Fractionation/ (Polybius square, straddling checkerboard, CT-37c conversion table, etc.)
 * 28) Contemporary Ciphers
 * 29) Symmetric Ciphers
 * 30) Enigma Machine
 * 31) /Solitaire cipher/
 * 32) One-Time Pads
 * 33) /Ciphersaber/
 * 34) Data Encryption Standard (DES)
 * 35) Advanced Encryption Standard
 * 36) /full-disk encryption/
 * 37) Asymmetric Ciphers
 * 38) Overview
 * 39) /A Basic Public Key Example/
 * 40) RSA
 * 41) ElGamal
 * 42) Elliptic Curve
 * 43) /Blum-Goldwasser/
 * 44) Hashes
 * 45) /MD5/
 * 46) /SHA-1/
 * 47) /SHA-2/
 * 48) /RadioGatún/, the direct predecessor of SHA-3
 * 49) /SHA-3/
 * 50) RIPEMD-160
 * 51) /Tiger/
 * 52) /message authentication/ code (often MAC); A MAC algorithm is sometimes called a keyed (cryptographic) hash function.
 * 53) /Protocols/
 * 54) Authentication protocols
 * 55) e.g. Kerberos
 * 56) Key exchange protocols
 * 57) Diffie-Hellman
 * 58) Secure Communications
 * 59) e.g. SSL, SSH
 * 60) /Generate a keypair using OpenSSL/

Part V: Cryptography and Society
 * 1) The Changing Nature of Cryptographic Use
 * 2) Cryptography, Governments and Laws
 * 3) Expectations of Normal Users

Part VI: Miscellaneous
 * 1) Future Possibilities
 * 2) Faster, More Parallel Linear Computers
 * 3) Glossary of Terms
 * 4) Further Reading
 * 5) Appendix A: Mathematical background
 * 6) Number Theory
 * 7) Group Theory
 * 8) Computational Complexity
 * 9) Prime numbers

 * 1) Currently ungrouped content
 * 2) Tabula Recta
 * 3) Commitment schemes
 * 4) Zero-knowledge proofs
 * 5) Open source implementation of cryptographic algorithms
 * 6) /initialization vector/
 * 7) /Linear Cryptanalysis/
 * 8) /Differential Cryptanalysis/

Pages to be merged into the text.

Cryptography/Prime Curve/Affine Coordinates

Cryptography/Prime Curve/Chudnovsky Coordinates

Cryptography/Prime Curve/Jacobian Coordinates

Cryptography/Prime Curve/Standard Projective Coordinates

Cryptography/Notes

Introducción a la Criptografía Crittografia

title: Cryptography


text:
Canadian History/Confederation

Canada's Obligation
By the 1860s, Great Britain became really concerned that Canada was more of a shining star than an asset to the Empire. British politicians did not like the expense of providing for the defence of the North American colonies from real or perceived threats from the Americans. The American Civil War only heightened fears in Canada of a potential invasion.

Americans, on the other hand, always seemed to have a group of people willing to go to war with Britain and invade British North America, often in high places (for example, Lincoln's Secretary of State, Seward). Britain's trade with the United States at this time had simply become too valuable to jeopardize by maintaining a colonial system in British North America, so prominent British politicians began the process of pushing Canada "out of the nest," so to speak.

However, the process was not simple. British North America consisted of no less than seven colonies, and the vast territory of Rupert's Land owned and run by Hudson's Bay Company. Uniting this area would prove to be difficult.

--- The following passage is inaccurate -- Confederation was achieved for many reasons. Canada West and Canada East felt that uniting the colonies would help make all of the colonies stronger, more economically stable, and would make the government system more fair. The maritimes, who were having a boom period, were disinclined to join confederation. They wanted to join together the maritime colonies and have a separate country for only them, however, the Americans had just finished the Civil War, and had about as many soldiers as all the colonies that were thinking about confederation did combined, and posed a real threat to the colonies. The maritimes thought about it, and with the help of a conference with John A. Macdonald decided to join confederation. The only maritime colonies that didn't join were Newfoundland and Prince Edward Island, which would join later on. At the Quebec conference, representatives from all the participating colonies came together and constructed the 72 Resolutions which outlined all of the laws that the new country Canada would have.

title: Canadian History/Confederation


text:
Lucid Dreaming/Using

Dream stabilization
Once you are able to dream lucidly, you may find that it is difficult to stay in the dream; for example, you may wake instantly or the dream may start “fading” which is characterized by loss or degradation of any of the senses, especially vision. Alternatively, a new lucid dreamer could easily forget that they are in a dream, as a result of the shock of the sensation.

Don't worry if you wake immediately after becoming lucid. As you gain more experience of becoming lucid, it will come as less of a shock and you’ll be less likely to wake up. Make sure you do a reality check to be sure you’re not still dreaming. As you gain more experience, you will have an easier time identifying when and remembering that you are dreaming.

You can avoid more gradual fadings by stimulating your senses. This means listening for sounds, feeling around with your hands, and paying attention to what you see and smell. The idea here is to load your senses with stimulation from the dream so that your senses cannot shift to the real world. If you close your eyes, you are removing a great deal of sensory information and might wake up. Staring at a single point can cause effectively the same problem if you stop seeing everything else in your peripheral vision, or don't see enough movement. If you hear something loud in real life and are hearing nothing in the dream, your senses may shift to the real world, causing you to wake up.

Ideally you should be able to use the techniques below to stabilize your dream before it starts to fade (or “black out”). As always, prevention is better than treatment - and the more stable and vivid your dreams are, the more enjoyable they will be. However, if that doesn't work you may be able to use stabilization techniques to stop the fading; the spinning technique is probably the most effective in this case.

If you still can’t stabilize your dream, you may decide to try and wake up with the aim of remembering your dream as accurately as possible while its still fresh in your mind.

Hand Touching
Rub your hands together and concentrate on the rubbing. You should feel the friction and the heat of your hands. If you can concentrate on the feelings that this action generates, your dream is likely to stabilize and become more vivid and detailed. You can also keep one hand on your arm while exploring the dream for a constant sense of stimulation. This technique is most effective when used in conjunction with the “Slowing it down” technique, by staring at your hands while rubbing them together.

Spinning
You spin around in your dream much as you would if you suddenly want to feel dizzy in real life. The sensation of movement is the key here to stabilizing the dream. Many people report success with this technique, but it also tends to cause a complete change of your dream scene (see Changing the dream environment below). If the dream scene disappears completely (e.g., becomes black), it is necessary to visualize the dreamscape to return to the dream.

Slowing it down
Some people like to stabilize the dream by “stopping to smell the roses” and slowly staring at a dream object until it becomes clear. The dreamer would then look around elsewhere, noticing how detailed everything is, thereby stimulating the visual portion of the dream. However, others find this can cause their lucid dream to end. If you focus on one object for too long to the exclusion of everything else, you will likely wake up or lose the dream. It works best to pay attention to everything in your vision, including your peripheral vision, not just the center of the object you're staring at. If staring at a single object doesn't work for you, try to let your eyes wander around instead.

Touching your dream
If you feel that your dream is too abstract and fear that it might be fading, you can prevent this by grabbing hold of a solid object in your dream and focus on how real the sensation is. A good tip is to find something you know is stuck, for instance a table nailed to the ground, and pull it with all your muscular power (no supernatural powers!), and you should feel how solid it is. The idea is that you convince yourself that the dream is solid and real — through tactile stimulation — and nothing abstract.

Regaining waking memory or skills
This is also likely to enhance your degree of lucidity. Try to remember facts from your waking life, such as your phone number, address, etc., or do some simple math. Or, start reciting the lyrics to your favorite song. Or perhaps try some sports practice you know well — this all depends on which senses / methods of thought process you tend to rely on most in your waking life.

Dream Guide
Summon a DC (Dream character) that you expect to Guide you through the dream. Summoning is easier if you always expect this Guide to be there in a dream. The Guide is useful for escaping scary or unpredicted environments ("whooshing" you away, killing or unsummoning the threat, reminding you that you are in control.). Imagine this Guide as powerful, knowledgeable, and protective over you. Guides can also walk you through summoning, flying, shapeshifting, etc. and be useful for learning and controlling your dreams.

False awakening
A couple of the users on the ld4all.com forums have had success with creating a false awakening to stabilize a dream. If the above techniques are failing and you find your dream still fading, and you really want to continue your lucid dream, do the following:

 * 1) Expect to have a false awakening.
 * 2) When you think you wake up, perform a reality check.

You will either have a false awakening, reality check, and then end up with an even more vivid lucid dream, or will really wake up, perform a reality check, and realize that you just woke up (bad luck!).

The most important part of this is the reality check. This is what will continue your lucid dream. You should be performing reality checks when you wake up. If you plan to induce false awakenings in order to stabilize a dream, the reality check that you perform as you wake up is as important as the one that got you lucid, if not more.

Perform every check in the book until you are positively, absolutely, and completely sure that you aren’t dreaming. A series of 10 reality checks is more likely to produce dream results in a dream, especially if you are expecting dream results. This technique is for those who are desperate!

If you have had a good experience with this technique, please go to the talk page and post your experiences, as there have not been many anecdotes of it working yet. top

Recovering from lost visuals
There are a few things you can try to do if you lose your vision. Most of these are less likely to help prolong your dream than the above techniques.

You can also try these if you have just woken up and are lying in your bed. You may be able to return to your dream.

Autosuggestion
You can repeat over and over a phrase similar to “I can see my dream,” or otherwise enforce in your mind that you can see a dreamscape. (See Autosuggestion)

Visualising
You can visualise the scene as it would be if you could see it. You could take this as an opportunity to change the dreamscape by visualising a different environment from the previous one in the dream. This can be made easier by spinning as you visualize. (See Changing the dream environment below)

Changing the dream environment
You can change the dreamscape by simply visualizing a different environment. Stephen LaBerge, author of Exploring the World of Lucid Dreaming, suggests closing your eyes, spinning around, and visualizing a new location. Alan Worsley, a famous lucid dreamer, describes another technique of summoning a television and remote to switched dreamscapes. By simply “changing the channel” on the remote, imagine your surroundings switching to your desired location, as though you were switching through various television programs.

In both of these methods, details are key. The more details you provide for your next dreamscape, the easier it will be to get there. For example, if you wanted go to the Superbowl in your dreams, you might simply state:

 * “I want to be at the Superbowl.”

But this statement could be improved by adding details:

 * "I want be in the endzone seats, drinking a Coke, and wearing my favorite player's jersey at the Super Bowl."

Summoning objects into your dream
At some point in your lucid dreaming experience, you'll probably want to handle various objects, or talk with certain people. Both of these needs can be fulfilled by using your mind, and the power of suggestion. There is no set way to "make" things in the dream world; in fact, many lucid dreamers devise their own methods through experimentation. However, here are some of the more common "summoning" techniques:

 * Try reaching for objects that are not within your field of vision. For example, think to yourself: “When I reach into my pocket, there will be a green box of mints.” Then, attempt to actually take a green box of mints out of your pocket. Other variations of this include reaching behind you for an object, or reaching through a mirror in hopes of getting a hold of what you want.
 * To summon a person, you might say to yourself: “When I turn around, [person's name] will be standing in front of me,” or “When I walk through this mirror, I will see [person's name],” or “In a few moments, [person's name] will walk through that door (or around that corner).”
 * More experienced lucid dreamers can try making the object materialize right before their eyes. This will require a fair amount of concentration. Here is an example of this process:

 * I am lucid dreaming in my backyard, and it's currently night. Now, I don't like the dark in my lucid dreams because I'm more likely to wake up, and I fear there are monsters lurking around every corner. So, I want to make the sun appear so that it'll be daytime. Focusing on the horizon, I visualize the sun rising above it.

 * At first nothing happens, but I continue focusing and...yes! There's some light filtering over the horizon! And now the sun is rising to the sky and it settles there; so far, so good. But wait...the sky is still black. Peering at bit closer at the sun, I can just make out a faint ring of blue sky encircling it. Lifting my hand towards it I shout, "Blue!". The blue ring quickly spreads across the sky, creating the full daytime effect.”

 * Some dreamers may have success by closing their eyes and imagining the desired object in front of them once when they open their eyes.
 * Try using mechanical devices within the dream, such as a nearby lightswitch or button, to summon objects or people. (i.e. "When I flip this switch/press this button, X will appear.")
 * Convince yourself you have magical powers (or scientific). Then, use them to summon objects, shapeshift, etc. This can help you believe the creation of objects more easily.
 * (This one is dumb, but it works.) Begin singing Friend Like Me, and summon stuff to the beat. They may disappear after you finish singing, or start dancing, but hey, it's pretty darn fun.

Remember, in the dream world, your expectations shape your surroundings. If you think a big, scary monster is going to step out of the shadows and attack you...well, a big, scary monster probably is going to step out of the shadows and attack you. So, don't be a victim; take control of your thoughts and use them to your advantage. top

What you can do
This final section should see you off with a few ideas of what to do in a dream.

It is advised to have a clear purpose for your lucid dreams whenever you go to sleep. In other words, every night you consider what you want to do when you have a lucid dream, and select one thing, or perhaps two or three if you are skilled. Avoid this:

 * "What am I gonna do what am I gonna do? I wanna fly, walk through walls, eat until my stomach explodes, spy on my neighbours, drive in a car real fast, woooeeey I'm gonna . . ."

You will either end up doing none of these things in your dream or getting overexcited and waking up.

Now that that’s clear, here’s a list of possible things you could do, ordered in difficulty. Remember that you might find some things unusually hard (or easy) compared to most lucid dreamers, this is perfectly normal! This is a very rough guide — if you’ve managed something in the Easy section, don't be scared to try for something from the Medium section.

Easy

 * Fly
 * Most people enjoy flying around in dreams. There are different styles of flight that people use, each with a varied level of success for each individual. Methods such as “swimming through the air”, “Superman style” (one arm outstretched), “Neo style” (both arms at your side), and “Airplane style” (both arms out) ,"eagle style" (gliding through the air currents, using your fingered wings to navigate altitudes) are often used. There are a few methods of getting up into the air, such as simply jumping (you can jump really high in dreams if you believe it) or imagining a great force pushing you from your feet or walking up on air as though it is a staircase. Some people summon jetpacks and slip them on to fly. Be creative and dream up your own methods.
 * Explore your dream world
 * Be warned, you are quite likely to forget you are dreaming when exploring! Doing reality checks often and muttering to yourself about how real everything seems can help to avoid this. You can also ask a dream character to tag along with you and remind you when you forget that you’re dreaming.
 * Walk through a mirror or wall
 * You can pass through dream objects such as walls, glass, trees, and everything else. Confidence is really the key here. Some variations on going through stuff can be going in slowly, wiggling your finger in first, or running quickly into the object and telling yourself you would go through it. Some people particularly like to go through mirrors because of the unpredictable effects this action produces. However, if you tell yourself you will end up at a certain location before passing through a mirror, you can change the dream scene quickly. Be warned, some people experience nothing and wake up after passing through. You may want to hold your arm to keep yourself in the dream.
 * Look at the sky
 * People often report amazing skies in lucid dreams. You can also shout colors at it and paint some sunrises.
 * Show off to your friends (“Hey guys; I can go through this wall!”)
 * Do plenty of sports (trampolining, skiing, swimming, dancing, etc.)
 * Use various power such as Telekinesis and magic (a shortcut if you are having problems would be to summon a magic wand/staff or other device)
 * Try to read a book that you have never read and remember the content
 * Try to browse the Internet and visit sites that you've never visited
 * Use things that you have never used
 * Last but not least: Edit Wikipedia/Wikibooks articles (see question 103 of the Wikipediholic Test) and see if the changes remain when you awake!

Medium

 * Eat until you’re near bursting!
 * Teleport
 * Create some dream characters (possibly from a book or film)
 * Try to find your spirit guide
 * Experiments (in fact, researchers will often want people of various skills)
 * Body swapping/possession (where you enter a different body)
 * Morph
 * Take some drugs (this is more realistic if you’ve done so in real life)
 * Many people have also experienced realistic effects when trying drugs in dreams that they have never taken in real life.
 * Drive a vehicle (This is especially fun if you haven't ever driven in real life)
 * Fight
 * Nobody can tell you what you should and should not do in your dreams; the choice remains up to you.
 * Use weapons
 * It is usually more interesting to use melee weapons (knives, swords, brass knuckles) than projectile weapons. Machine guns and pistols often run out of ammo and summoning it can be difficult. Misfires and jamming is also common. (Your subconscious expectations will shape your dreamscape in all manner of ways, If you believe it is hard to accomplish, if you believe it will jam or misfire, it will. I have had no issues with weaponry such as firearms in my dreams what-so-ever, take this "advice" lightly.) However this can be overcome by using Directed Energy Weapons (Lasers, Plasma/pulse rifles), or weapons that can't jam (bows, simple firearms like muskets and so on).
 * "Beat up" your enemies

Hard

 * Have sex
 * The excitement, or closing your eyes, can cause you to wake up. An additional reason for waking up may be fixing your eyes on your partner, as holding a gaze for long is also known to cause waking up. Also your dream partner has a strange way of transforming in the midst of ecstasy. Finding a sex partner isn't very hard, it's keeping them that is difficult. That is why it is best to not panic when they are transforming and accept them for what your subconscious brings you.
 * More morphing like 360 degree vision, sonar vision, etc.
 * Create false memories, etc. False memories can be made by having a lucid dream, but scripting it so you will think it is real, e.g. you think what happened in your dream happened in real life. This is hard because you will have to forget it is a dream while staying lucid (knowing it is a dream).
 * Compose music or poems (or request them from your subconscious)
 * Build a fantasy dream world! (some people build a dream world naturally)
 * Lucid Crossroads
 * Astral Pulse Island
 * H.P. Lovecraft's Dreamlands
 * Have precognition (your subconscious can be very good at predicting the future with relationships and career)
 * Experience death. This could be a very harsh experience, and depending on your religious or philosophical beliefs may summon you into a different world or nothingness.
 * Ask the dream to show you your worst fears/deepest traumas/etc. (be prepared for some bad stuff to surface)
 * Build/use impossible objects, such as hypercubes, Klein bottles, etc.
 * Rewind time

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Conclusion
With all the techniques in this book, you may feel overwhelmed and uncertain of what to do next. Don't worry — just choose a few techniques to “map your way to lucidity”, decide on a few things you will want to do from this page, and start!

If you are still unsure of what to do, don’t worry — you might happen to have a lucid dream tonight!

If you are beginning to feel a compulsive thirst for more information about dreams, head over to the Further Reading section for the sites to satisfy your cravings. Remember to come back occasionally and help make the wikibook grow!

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Sueño lúcido/Uso Sogno lucido/Uso

title: Lucid Dreaming/Using


text:
User talk:67.30.103.89

If you are considering being a serious contributor to the wikibook :) it would be appreciated if you were to sign up. You don't even need to enter your email, completely anonymous, but it shows exactly who is who. To reply, click on the (talk) link and click on Edit this page. r3m0t (cont) (talk) 12:05, 24 Jan 2004 (PST)

title: User talk:67.30.103.89


text:
Vietnamese/History

It seems likely that in the distant past Vietnamese shared more characteristics common to other languages in the Austroasiatic family, such as an inflectional morphology and a richer set of consonant clusters, which have subsequently disappeared from the language. However, Vietnamese appears to have been heavily influenced by its location in the Southeast Asian sprachbund—with the result that it has acquired or converged toward characteristics such as isolating morphology and tonogenesis. These characteristics, which may or may not have been part of proto-Austroasiatic, nonetheless have become part of many of the philologically unrelated languages of Southeast Asia—for example, Thai (one of the Tai-Kadai languages), Tsat (a member of the Malayo-Polynesian language group within Austronesian), and Vietnamese each developed tones as a phonemic feature, although their respective ancestral languages were not originally tonal.

The Vietnamese language has similarities with Cantonese in regard to the specific intonations and unreleased plosive consonant endings, a legacy of archaic Chinese that can also be found in Korean.

The ancestor of the Vietnamese language was originally based in the area of the Red River in what is now northern Vietnam, and during the subsequent expansion of the Vietnamese language and people into what is now central and southern Vietnam (through conquest of the ancient nation of Champa and the Khmer of the Mekong delta in the vicinity of present-day Ho Chi Minh City), Vietnamese was linguistically influenced primarily by Indic and Malayo-Polynesian languages at first, until Chinese came to politically predominate the Vietnamese area toward the middle of the first millennium AD.

With the rise of Chinese political dominance came a radical importation of Chinese vocabulary and grammatical influence. As Chinese was, for a prolonged period, the only medium of literature and government, as well as the primary language of the ruling class in Vietnam, much of the lexicon of Vietnamese in all realms consists of Hán Việt (Sino-Vietnamese) words. In fact, as the vernacular language of Vietnam gradually grew in prestige toward the beginning of the second millennium, the Vietnamese language was written using Chinese characters (see Chữ nôm) adapted to write Vietnamese, in a similar pattern as used in Japan (see kanji), Korea and other countries in the Chinese cultural sphere. The Nôm writing reached its zenith in the 18th century when many Vietnamese writers and poets composed their works in Chữ Nôm, most notably Nguyễn Du and Hồ Xuân Hương (dubbed "the Queen of Nôm poetry").

As contact with the West grew, the Quốc Ngữ system of Romanized writing was developed in the 17th century by Portuguese and other Europeans involved in proselytizing and trade in Vietnam. When France invaded Vietnam in the late 19th century, French gradually replaced Chinese as the official language in education and government. Vietnamese adopted many French terms, such as đầm (dame, from madame), ga (train station, from gare), and va-li (valise). In addition, many Sino-Vietnamese terms were devised for Western ideas imported through the French. However, the Romanized script did not come to predominate until the beginning of the 20th century, when education became widespread and a simpler writing system was found more expedient for teaching and communication with the general population.

title: Vietnamese/History


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Cryptography/Introduction

Cryptography is the study of information hiding and verification. It includes the protocols, algorithms and strategies to securely and consistently prevent or delay unauthorized access to sensitive information and enable verifiability of every component in a communication.

Cryptography is derived from the Greek words: kryptós, "hidden", and gráphein, "to write" - or "hidden writing". People who study and develop cryptography are called cryptographers. The study of how to circumvent the use of cryptography for unintended recipients is called cryptanalysis, or codebreaking. Cryptography and cryptanalysis are sometimes grouped together under the umbrella term cryptology, encompassing the entire subject. In practice, "cryptography" is also often used to refer to the field as a whole, especially as an applied science. At the dawn of the 21 century in an ever more interconnected and technological world cryptography started to be ubiquitous as well as the reliance on the benefits it brings, especially the increased security and verifiability.

Cryptography is an interdisciplinary subject, drawing from several fields. Before the time of computers, it was closely related to linguistics. Nowadays the emphasis has shifted, and cryptography makes extensive use of technical areas of mathematics, especially those areas collectively known as discrete mathematics. This includes topics from number theory, information theory, computational complexity, statistics and combinatorics. It is also a branch of engineering, but an unusual one as it must deal with active, intelligent and malevolent opposition.

An example of the sub-fields of cryptography is steganography — the study of hiding the very existence of a message, and not necessarily the contents of the message itself (for example, microdots, or invisible ink) — and traffic analysis, which is the analysis of patterns of communication in order to learn secret information.

When information is transformed from a useful form of understanding to an opaque form of understanding, this is called encryption. When the information is restored to a useful form, it is called decryption. Intended recipients or authorized use of the information is determined by whether the user has a certain piece of secret knowledge. Only users with the secret knowledge can transform the opaque information back into its useful form. The secret knowledge is commonly called the key, though the secret knowledge may include the entire process or algorithm that is used in the encryption/decryption. The information in its useful form is called plaintext (or cleartext); in its encrypted form it is called ciphertext. The algorithm used for encryption and decryption is called a cipher (or cypher).

Common goals in cryptography
In essence, cryptography concerns four main goals. They are:

 * 1) message confidentiality (or privacy): Only an authorized recipient should be able to extract the contents of the message from its encrypted form. Resulting from steps to hide, stop or delay free access to the encrypted information.
 * 2) message integrity: The recipient should be able to determine if the message has been altered.
 * 3) sender authentication: The recipient should be able to verify from the message, the identity of the sender, the origin or the path it traveled (or combinations) so to validate claims from emitter or to validated the recipient  expectations.
 * 4) sender non-repudiation: The remitter should not be able to deny sending the message.

Not all cryptographic systems achieve all of the above goals. Some applications of cryptography have different goals; for example some situations require repudiation where a participant can plausibly deny that they are a sender or receiver of a message, or extend this goals to include variations like:

 * 1) message access control: Who are the valid recipients of the message.
 * 2) message availability: By providing means to limit the validity of the message, channel, emitter or recipient in time or space.

Common forms of cryptography
Cryptography involves all legitimate users of information having the keys required to access that information.
 * If the sender and recipient must have the same key in order to encode or decode the protected information, then the cipher is a symmetric key cipher since everyone uses the same key for the same message. The main problem is that the secret key must somehow be given to both the sender and recipient privately. For this reason, symmetric key ciphers are also called private key (or secret key) ciphers.
 * If the sender and recipient have different keys respective to the communication roles they play, then the cipher is an asymmetric key cipher as different keys exist for encoding and decoding the same message. It is also called public key encryption as the user publicly distributes one of the keys without a care for secrecy. In the case of confidential messages to the user, they distribute the encryption key. Asymmetric encryption relies on the fact that possession of the encryption key will not reveal the decryption key.
 * Digital Signatures are a form of authentication with some parallels to public-key encryption. The two keys are the public verification key and the secret signature key. As in public-key encryption, the verification key can be distributed to other people, with the same caveat that the distribution process should in some way authenticate the owner of the secret key. Security relies on the fact that possession of the verification key will not reveal the signature key.
 * Hash Functions are unkeyed message digests with special properties.

Other:

Poorly designed, or poorly implemented, crypto systems achieve them only by accident or bluff or lack of interest on the part of the opposition. Users can, and regularly do, find weaknesses in even well-designed cryptographic schemes from those of high reputation.

Even with well designed, well implemented, and properly used crypto systems, some goals aren't practical (or desirable) in some contexts. For example, the sender of the message may wish to be anonymous, and would therefore deliberately choose not to bother with non-repudiation. Alternatively, the system may be intended for an environment with limited computing resources, or message confidentiality might not be an issue.

In classical cryptography, messages are typically enciphered and transmitted from one person or group to some other person or group. In modern cryptography, there are many possible options for "sender" or "recipient". Some examples, for real crypto systems in the modern world, include:

 * 1) a computer program running on a local computer,
 * 2) a computer program running on a 'nearby' computer which 'provides security services' for users on other nearby systems,
 * 3) a human being (usually understood as 'at the keyboard').  However, even in this example, the presumed human is not generally taken to actually encrypt or sign or decrypt or authenticate anything. Rather, he or she instructs a computer program to perform these actions.  This 'blurred separation' of human action from actions which are presumed (without much consideration) to have 'been done by a human' is a source of problems in crypto system design, implementation, and use.  Such problems are often quite subtle and correspondingly obscure; indeed, generally so, even to practicing cryptographers with knowledge, skill, and good engineering sense.

When confusion on these points is present (e.g., at the design stage, during implementation, by a user after installation, or ...), failures in reaching each of the stated goals can occur quite easily—often without notice to any human involved, and even given a perfect cryptosystem. Such failures are most often due to extra-cryptographic issues; each such failure demonstrates that good algorithms, good protocols, good system design, and good implementation do not alone, nor even in combination, provide 'security'. Instead, careful thought is required regarding the entire crypto system design and its use in actual production by real people on actual equipment running 'production' system software (e.g., operating systems) -- too often, this is absent or insufficient in practice with real-world crypto systems.

Although cryptography has a long and complex history, it wasn't until the 19th century that it developed anything more than ad hoc approaches to either encryption or cryptanalysis (the science of finding weaknesses in crypto systems). Examples of the latter include Charles Babbage's Crimean War era work on mathematical cryptanalysis of polyalphabetic ciphers, repeated publicly rather later by the Prussian Kasiski. During this time, there was little theoretical foundation for cryptography; rather, understanding of cryptography generally consisted of hard-won fragments of knowledge and rules of thumb; see, for example, Auguste Kerckhoffs' crypto writings in the latter nineteenth century. An increasingly mathematical trend accelerated up to World War II (notably in William F. Friedman's application of statistical techniques to cryptography and in Marian Rejewski's initial break into the German Army's version of the Enigma system). Both cryptography and cryptanalysis have become far more mathematical since WWII. Even then, it has taken the wide availability of computers, and the Internet as a communications medium, to bring effective cryptography into common use by anyone other than national governments or similarly large enterprise.

External links

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Crittografia/Introduzione alla crittografia

title: Cryptography/Introduction


text:
Cryptography/History

Classical Cryptography
The earliest known use of cryptography is found in non-standard hieroglyphs carved into monuments from Egypt's Old Kingdom (ca 4500 years ago). These are not thought to be serious attempts at secret communications, however, but rather to have been attempts at mystery, intrigue, or even amusement for literate onlookers. These are examples of still another use of cryptography, or of something that looks (impressively if misleadingly) like it. Later, Hebrew scholars made use of simple Substitution ciphers (such as the Atbash cipher) beginning perhaps around 500 to 600 BCE. Cryptography has a long tradition in religious writing likely to offend the dominant culture or political authorities.

The Greeks of Classical times are said to have known of ciphers (e.g., the scytale transposition cypher claimed to have been used by the Spartan military). Herodutus tells us of secret messages physically concealed beneath wax on wooden tablets or as a tattoo on a slave's head concealed by regrown hair (these are not properly examples of cryptography per se; see secret writing). The Romans certainly did (e.g., the Caesar cipher and its variations). There is ancient mention of a book about Roman military cryptography (especially Julius Caesar's); it has been, unfortunately, lost.

In India, cryptography was apparently well known. It is recommended in the Kama Sutra as a technique by which lovers can communicate without being discovered. This may imply that cryptanalytic techniques were less than well developed in India ca 500 CE.

Cryptography became (secretly) important still later as a consequence of political competition and religious analysis. For instance, in Europe during and after the Renaissance, citizens of the various Italian states, including the Papacy, were responsible for substantial improvements in cryptographic practice (e.g., polyalphabetic ciphers invented by Leon Alberti ca 1465). And in the Arab world, religiously motivated textual analysis of the Koran led to the invention of the frequency analysis technique for breaking monoalphabetic substitution cyphers sometime around 1000 CE.

Cryptography, cryptanalysis, and secret agent betrayal featured in the Babington plot during the reign of Queen Elizabeth I which led to the execution of Mary, Queen of Scots. And an encrypted message from the time of the Man in the Iron Mask (decrypted around 1900 by Étienne Bazeries) has shed some, regrettably non-definitive, light on the identity of that legendary, and unfortunate, prisoner. Cryptography, and its misuse, was involved in the plotting which led to the execution of Mata Hari and even more reprehensibly, if possible, in the travesty which led to Dreyfus' conviction and imprisonment, both in the early 20th century. Fortunately, cryptographers were also involved in setting Dreyfus free; Mata Hari, in contrast, was shot.

Mathematical cryptography leapt ahead (also secretly) after World War I. Marian Rejewski, in Poland, attacked and 'broke' the early German Army Enigma system (an electromechanical rotor cypher machine) using theoretical mathematics in 1932. The break continued up to '39, when changes in the way the German Army's Enigma machines were used required more resources than the Poles could deploy. His work was extended by Alan Turing, Gordon Welchman, and others at Bletchley Park beginning in 1939, leading to sustained breaks into several other of the Enigma variants and the assorted networks for which they were used. US Navy cryptographers (with cooperation from British and Dutch cryptographers after 1940) broke into several Japanese Navy crypto systems. The break into one of them famously led to the US victory in the Battle of Midway. A US Army group, the SIS, managed to break the highest security Japanese diplomatic cipher system (an electromechanical 'stepping switch' machine called Purple by the Americans) even before WWII began. The Americans referred to the intelligence resulting from cryptanalysis, perhaps especially that from the Purple machine, as 'Magic'. The British eventually settled on 'Ultra' for intelligence resulting from cryptanalysis, particularly that from message traffic enciphered by the various Enigmas. An earlier British term for Ultra had been 'Boniface'.

World War II Cryptography
By World War II mechanical and electromechanical cryptographic cipher machines were in wide use, but they were impractical manual systems. Great advances were made in both practical and mathematical cryptography in this period, all in secrecy. Information about this period has begun to be declassified in recent years as the official 50-year (British) secrecy period has come to an end, as the relevant US archives have slowly opened, and as assorted memoirs and articles have been published.

The Germans made heavy use (in several variants) of an electromechanical rotor based cypher system known as Enigma. The German military also deployed several mechanical attempts at a one-time pad. Bletchley Park called them the Fish cyphers, and Max Newman and colleagues designed and deployed the world's first programmable digital electronic computer, the Colossus, to help with their cryptanalysis. The German Foreign Office began to use the one-time pad in 1919; some of this traffic was read in WWII partly as the result of recovery of some key material in South America that was insufficiently carefully discarded by a German courier.

The Japanese Foreign Office used a locally developed electrical stepping switch based system (called Purple by the US), and also used several similar machines for attaches in some Japanese embassies. One of these was called the 'M-machine' by the US, another was referred to as 'Red'. All were broken, to one degree or another by the Allies.

Other cipher machines used in WWII included the British Typex and the American SIGABA; both were electromechanical rotor designs similar in spirit to the Enigma.

Modern Cryptography
The era of modern cryptography really begins with Claude Shannon, arguably the father of mathematical cryptography. In 1949 he published the paper Communication Theory of Secrecy Systems in the Bell System Technical Journal, and a little later the book Mathematical Theory of Communication with Warren Weaver. These, in addition to his other works on information and communication theory established a solid theoretical basis for cryptography and for cryptanalysis. And with that, cryptography more or less disappeared into secret government communications organizations such as the NSA. Very little work was again made public until the mid '70s, when everything changed.

1969 saw two major public (i.e., non-secret) advances. First was the DES (Data Encryption Standard) submitted by IBM, at the invitation of the National Bureau of Standards (now NIST), in an effort to develop secure electronic communication facilities for businesses such as banks and other large financial organizations. After 'advice' and modification by the NSA, it was adopted and published as a FIPS Publication (Federal Information Processing Standard) in 1977 (currently at FIPS 46-3). It has been made effectively obsolete by the adoption in 2001 of the Advanced Encryption Standard, also a NIST competition, as FIPS 197. DES was the first publicly accessible cypher algorithm to be 'blessed' by a national crypto agency such as NSA. The release of its design details by NBS stimulated an explosion of public and academic interest in cryptography. DES, and more secure variants of it (such as 3DES or TDES; see FIPS 46-3), are still used today, although DES was officially supplanted by AES (Advanced Encryption Standard) in 2001 when NIST announced the selection of Rijndael, by two Belgian cryptographers. DES remains in wide use nonetheless, having been incorporated into many national and organizational standards. However, its 56-bit key-size has been shown to be insufficient to guard against brute-force attacks (one such attack, undertaken by cyber civil-rights group The Electronic Frontier Foundation, succeeded in 56 hours—the story is in Cracking DES, published by O'Reilly and Associates). As a result, use of straight DES encryption is now without doubt insecure for use in new crypto system designs, and messages protected by older crypto systems using DES should also be regarded as insecure. The DES key size (56-bits) was thought to be too small by some even in 1976, perhaps most publicly Whitfield Diffie. There was suspicion that government organizations even then had sufficient computing power to break DES messages and that there may be a back door due to the lack of randomness in the 'S' boxes.

Second was the publication of the paper New Directions in Cryptography by Whitfield Diffie and Martin Hellman. This paper introduced a radically new method of distributing cryptographic keys, which went far toward solving one of the fundamental problems of cryptography, key distribution. It has become known as Diffie-Hellman key exchange. The article also stimulated the almost immediate public development of a new class of enciphering algorithms, the asymmetric key algorithms.

Prior to that time, all useful modern encryption algorithms had been symmetric key algorithms, in which the same cryptographic key is used with the underlying algorithm by both the sender and the recipient who must both keep it secret. All of the electromechanical machines used in WWII were of this logical class, as were the Caesar and Atbash cyphers and essentially all cypher and code systems throughout history. The 'key' for a code is, of course, the codebook, which must likewise be distributed and kept secret.

Of necessity, the key in every such system had to be exchanged between the communicating parties in some secure way prior to any use of the system (the term usually used is 'via a secure channel') such as a trustworthy courier with a briefcase handcuffed to a wrist, or face-to-face contact, or a loyal carrier pigeon. This requirement rapidly becomes unmanageable when the number of participants increases beyond some (very!) small number, or when (really) secure channels aren't available for key exchange, or when, as is sensible crypto practice keys are changed frequently. In particular, a separate key is required for each communicating pair if no third party is to be able to decrypt their messages. A system of this kind is also known as a private key, secret key, or conventional key cryptosystem. D-H key exchange (and succeeding improvements) made operation of these systems much easier, and more secure, than had ever been possible before.

In contrast, with asymmetric key encryption, there is a pair of mathematically related keys for the algorithm, one of which is used for encryption and the other for decryption. Some, but not all, of these algorithms have the additional property that one of the keys may be made public since the other cannot be (by any currently known method) deduced from the 'public' key. The other key in these systems is kept secret and is usually called, somewhat confusingly, the 'private' key. An algorithm of this kind is known as a public key / private key algorithm, although the term asymmetric key cryptography is preferred by those who wish to avoid the ambiguity of using that term for all such algorithms, and to stress that there are two distinct keys with different secrecy requirements.

As a result, for those using such algorithms, only one key pair is now needed per recipient (regardless of the number of senders) as possession of a recipient's public key (by anyone whomsoever) does not compromise the 'security' of messages so long as the corresponding private key is not known to any attacker (effectively, this means not known to anyone except the recipient). This unanticipated, and quite surprising, property of some of these algorithms made possible, and made practical, widespread deployment of high quality crypto systems which could be used by anyone at all. Which in turn gave government crypto organizations worldwide a severe case of heartburn; for the first time ever, those outside that fraternity had access to cryptography that wasn't readily breakable by the 'snooper' side of those organizations. Considerable controversy, and conflict, began immediately. It has not yet subsided. In the US, for example, exporting strong cryptography remains illegal; cryptographic methods and techniques are classified as munitions. Until 2001 'strong' crypto was defined as anything using keys longer than 40 bits—the definition was relaxed thereafter. (See S Levy's Crypto for a journalistic account of the policy controversy in the US).

Note, however, that it has NOT been proven impossible, for any of the good public/private asymmetric key algorithms, that a private key (regardless of length) can be deduced from a public key (or vice versa). Informed observers believe it to be currently impossible (and perhaps forever impossible) for the 'good' asymmetric algorithms; no workable 'companion key deduction' techniques have been publicly shown for any of them. Note also that some asymmetric key algorithms have been quite thoroughly broken, just as many symmetric key algorithms have. There is no special magic attached to using algorithms which require two keys.

In fact, some of the well respected, and most widely used, public key / private key algorithms can be broken by one or another cryptanalytic attack and so, like other encryption algorithms, the protocols within which they are used must be chosen and implemented carefully to block such attacks. Indeed, all can be broken if the key length used is short enough to permit practical brute force key search; this is inherently true of all encryption algorithms using keys, including both symmetric and asymmetric algorithms.

This is an example of the most fundamental problem for those who wish to keep their communications secure; they must choose a crypto system (algorithms + protocols + operation) that resists all attack from any attacker. There being no way to know who those attackers might be, nor what resources they might be able to deploy, nor what advances in cryptanalysis (or its associated mathematics) might in future occur, users may ONLY do the best they know how, and then hope. In practice, for well designed / implemented / used crypto systems, this is believed by informed observers to be enough, and possibly even enough for all(?) future attackers. Distinguishing between well designed / implemented / used crypto systems and crypto trash is another, quite difficult, problem for those who are not themselves expert cryptographers. It is even quite difficult for those who are.

Revision of modern history
In recent years public disclosure of secret documents held by the UK government has shown that asymmetric key cryptography, D-H key exchange, and the best known of the public key / private key algorithms (i.e., what is usually called the RSA algorithm), all seem to have been developed at a UK intelligence agency before the public announcement by Diffie and Hellman in '76. GCHQ has released documents claiming that they had developed public key cryptography before the publication of Diffie and Hellman's paper. Various classified papers were written at GCHQ during the 1960s and 1970s which eventually led to schemes essentially identical to RSA encryption and to Diffie-Hellman key exchange in 1973 and 1974. Some of these have now been published, and the inventors (James Ellis, Clifford Cocks, and Malcolm Williamson) have made public (some of) their work.

title: Cryptography/History


text:
Cryptography/Further reading

 * Anderson, Ross — Security Engineering, Wiley, advanced coverage of computer security issues, including cryptography, by one of its foremost practitioners, and most likely its best writer. Covers much more than merely cryptography. Brief on most topics due to the breadth of coverage. Exceptionally clearly written.
 * Bamford, James — The Puzzle Palace : A Report on America's Most Secret Agency ISBN 0140067485, and the more recent Body of Secrets. The best of a quite small group of books about the US Government's NSA. Most are inadequate, and untrustworthy, for various reasons, including an active reluctance to permit accurate information to be released in any form.
 * Ferguson, Niels and Bruce Schneier — Practical Cryptography, Wiley, 2003, ISBN 0471223573. Up to date cryptography reference. Covers both algorithms and protocols. This is an in depth consideration of one cryptographic problem, including paths not taken and some reasons why. Most of the material is not otherwise available in a single source. Some is not otherwise available. In a sense, a follow-up to 'Applied Cryptography'.
 * Kahn, David — The Codebreakers ISBN 0684831309 The best available single volume source for cryptographic history, at least for events up to the mid '60s (i.e., to just before DES and the public release of asymmetric key cryptography). The added chapter on more recent developments (in the most recent edition) is regrettably far too thin. See also his other publications on cryptography, and cryptographic history, which have been uniformly excellent.
 * Katz, Jonathan and Yehuda Lindell - Introduction to Modern Cryptography, CRC Press, 2007. A textbook introduction to modern cryptography, aimed at undergraduate computer science/mathematics majors as well as the technically educated public.
 * A. J. Menezes, P. C. van Oorschot and S. A. Vanstone — Handbook of Applied Cryptography ISBN 0849385237 (online version). Equivalent to Applied Cryptography in many ways, but seriously mathematical. For the technically inclined. Covers few meta-cryptographic topics, such as crypto system design.
 * Paar, Christof and Pelz, Jan — Understanding Cryptography, A Textbook for Students and Practitioners Springer, 2009. Very accessible introduction to practical cryptography, focus on being a textbook, i.e., it has pedagocical approach, problem sets, further reading sections etc.
 * Piper, Fred and Sean Murphy — Cryptography : A Very Short Introduction ISBN 0192803158 This book quickly sketches out the major goals, uses, methods, and developments in cryptography.
 * Schneier, Bruce — Applied Cryptography, 2 ed, Wiley, ISBN 0471117099. The best single volume available covering modern cryptographic practice and possibilities. About as comprehensive as a single volume could have been. Well written, not overly mathematical, and so accessible — mostly — to the non-technical.
 * Schneier, Bruce — Secrets and Lies, Wiley, ISBN 0471253111, a discussion of the context within which cryptography and cryptosystems work. Meta-cryptography, if you will. Required reading for would-be cryptographers, and nearly so for all cryptography users.
 * Singh, Simon — The Code Book ISBN 1857028899. An anecdotal introduction to the history of cryptography, but much better than such an approach might be expected to produce. Covers more recent material than does Kahn's The Codebreakers. Well written. Sadly, the included cryptanalytic contest has been won and the prize awarded; the cyphers are still worth having a go at, however.
 * Sweigart, Al — Hacking Secret Ciphers with Python ISBN 978-1482614374. A complete beginners guide to programming and classic cryptography ciphers. This free book presents several programs that attack various ciphers and explains how their source code works.
 * University of Cambridge. NRICH. "Codes and cryptography". Some of these resources are suitable even for very young students of cryptography.
 * Wikipedia: Wikipedia:WikiProject Cryptography, Wikipedia:WikiReader/Cryptography, Wikipedia Book:Cryptography

title: Cryptography/Further reading


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Cryptography/Transposition ciphers

A transposition cipher encodes a message by reordering the plaintext in some definite way. Mathematically, it can be described as applying some sort of bijective function. The receiver decodes the message using the reordering in the opposite way, setting the ordering right again. Mathematically this means using the inverse function of the original encoding function.

For example, to encrypt the sentence "A simple kind of transposition cipher writes the message into a rectangle by rows and reads it out by columns," we could use the following rectangle:

Asimplekin doftranspo sitionciph erwritesth emessagein toarectang lebyrowsan dreadsitou tbycolumns

Then the encrypted text would be "Adsee tldts oirmo erbif tweab eymti rsrya cproi serdo lanta cosle ncegt wiuks iseas tmipp tinao nnohh ngnus."

This cipher is often complicated by permuting the rows and columns, as in columnar transposition.

Columnar transposition
The standard columnar transposition consists of writing the key out as column headers, then writing the message out in successive rows beneath these headers (filling in any spare spaces with nulls), finally, the message is read off in columns, in alphabetical order of the headers. For example suppose we have a key of 'ZEBRAS' and a message of 'WE ARE DISCOVERED. FLEE AT ONCE'. We start with:

Then read it off as: EVLNE ACDTK ESEAQ ROFOJ DEECU WIREE To decipher it, the recipient has to work out the column lengths by dividing the message length by the key length. Then he can write the message out in columns again, then re-order the columns by reforming the key word.

Double transposition
A single columnar transposition could be attacked by guessing possible column lengths, writing the message out in its columns (but in the wrong order, as the key is not yet known), and then looking for possible anagrams. Thus to make it stronger, a double transposition was often used. This is simply a columnar transposition applied twice, with two different keys of different (preferably relatively prime) length. Double transposition was generally regarded as the most complicated cipher that an agent could operate reliably under difficult field conditions. It was in actual use at least as late as World War II (e.g. poem code).

Grille
Another type of transpositional cipher uses a grille. This is a square piece of cardboard with holes in it such that each cell in the square appears in no more than one position when the grille is rotated to each of its four positions. Only grilles with an even number of character positions in the square can satisfy this requirement. As much message as will fit in the grille is written, then it is turned to another position and more message is written. Removing the cardboard reveals the cyphertext.

The following diagram shows the message "JIM ATTACKS AT DAWN" encoded using a 4x4 grille.

The top row shows the cardboard grille and the bottom row shows the paper underneath the grille at five stages of encoding:

 * 1) blank grille on the paper.
 * 2) first four letters written in the blanks.
 * 3) grille rotated one position, second set of letters written.
 * 4) grille rotated two positions, third set of letters written.
 * 5) grille rotated three positions, fourth set of letters written.

After the letters in the message have all been written out, the ciphertext can be read from the paper: "JKDT STAA AIWM NCAT".

The sender and receiver must agree on the initial orientation of the grille, the direction to rotate the grille, the order in which to use the spaces on the grille, and the order in which to read the ciphertext characters from the paper.

title: Cryptography/Transposition ciphers


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Cryptography/Caesar cipher

A Caesar cipher (also known as a shift cipher) is a substitution cipher in which the cipher alphabet is merely the plain alphabet rotated left or right by some number of positions. For instance, here is a Caesar cipher using a right rotation of three places:

Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ Cipher: XYZABCDEFGHIJKLMNOPQRSTUVW

To encipher a message, simply look up each letter of the message in the "plain" line and write down the corresponding letter in the "cipher" line. To decipher, do the reverse. Because this cipher is a group, multiple encryptions and decryptions provide NO additional security against any attack, including brute-force.

The Caesar cipher is named for Julius Caesar, who allegedly used it to protect messages of military significance. It was secure at the time because Caesar's enemies could often not even read plaintext, let alone ciphertext. But since it can be very easily broken even by hand, it has not been adequate for secure communication for at least a thousand years since the Arabs discovered frequency analysis and so made all simple substitution cyphers almost trivially breakable. An ancient book on cryptography, now lost, is said to have discussed the use of such cyphers at considerable length. Our knowledge is due to side comments by other writers, such as Suetonius.

Indeed, the Caesar cypher is much weaker than the (competently done) random substitution ciphers used in newspaper cryptogram puzzles. The most common places Caesar ciphers are found today are in children's toys such as secret decoder rings and in the ROT13 cipher on Usenet (which, of course, is meant to be trivial to decrypt)...

title: Cryptography/Caesar cipher


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Cryptography/Frequency analysis

In the field of cryptanalysis, frequency analysis is a methodology for "breaking" simple substitution ciphers, not just the Caesar cipher but all monoalphabetic substitution ciphers. These ciphers replace one letter of the plaintext with another to produce the cyphertext, and any particular letter in the plaintext will always, in the simplest and most easily breakable of these cyphers, turn into the same letter in the cypher. For instance, all E's will turn into X's. Frequency analysis is based on the fact that certain letters, and combinations of letters, appear with characteristic frequency in essentially all texts in a particular language. For instance, in the English language E is very common, while X is not. Likewise, ST, NG, TH, and QU are common combinations, while XT, NZ, and QJ are exceedingly uncommon, or "impossible". Given our example of all E's turning into X's, a cyphertext message containing lots of X's already seems to suggest one pair in the substitution mapping.

In practice the use of frequency analysis consists of first counting the frequency of cypher text letters and then assigning "guessed" plaintext letters to them. Many letters will occur with roughly the same frequency, so a cypher with X's may indeed map X onto R, but could also map X onto G or M. But some letters in every language using letters will occur more frequently; if there are more X's in the cyphertext than anything else, it's a good guess for English plaintext that X stands for E. But T and A are also very common in English text, so X might be either of them. It's very unlikely to be a Z or Q which aren't common in English. Thus the cryptanalyst may need to try several combinations of mappings between cyphertext and plaintext letters. Once the common letters are 'solved', the technique typically moves on to pairs and other patterns. These often have the advantage of linking less commonly used letters in many cases, filling in the gaps in the candidate mapping table being built. For instance, Q and U nearly always travel together in that order in English, but Q is rare.

Frequency analysis is extremely effective against the simpler substitution cyphers and will break astonishingly short ciphertexts with ease. This fact was the basis of Edgar Allan Poe's claim, in his famous newspaper cryptanalysis demonstrations in the middle 1800's, that no cypher devised by man could defeat him. Poe was overconfident in his proclamation, however, for polyalphabetic substitution cyphers (invented by Alberti around 1467) defy simple frequency analysis attacks. The electro-mechanical cypher machines of the first half of the 20th century (e.g., the Hebern? machine, the Enigma, the Japanese Purple machine, the SIGABA, the Typex, ...) were, if properly used, essentially immune to straightforward frequency analysis attack, being fundamentally polyalphabetic cyphers. They were broken using other attacks.

Frequency analysis was first discovered in the Arab world, and is known to have been in use by about 1000 CE. It is thought that close textual study of the Koran first brought to light that Arabic has a characteristic letter frequency which can be used in cryptoanalysis. Its use spread, and was so widely used by European states by the Renaissance that several schemes were invented by cryptographers to defeat it. These included use of several alternatives to the most common letters in otherwise monoalphabetic substitution cyphers (i.e., for English, both X and Y cyphertext might mean plaintext E), use of several alphabets—chosen in assorted, more or less, devious ways (Leon Alberti seems to have been the first to propose this), culminating in such schemes as using only pairs or triplets of plaintext letters as the 'mapping index' to cyphertext letters (e.g., the Playfair cipher invented by Charles Wheatstone in the mid 1800s). The disadvantage of all these attempts to defeat frequency counting attacks is that it increases complication of both encyphering and decyphering, leading to mistakes. Famously, a British Foreign Secretary is said to have rejected the Playfair cipher because, even if school boys could learn it as Wheatstone and Playfair had shown, 'our attaches could never learn it!'.

Frequency analysis requires a basic understanding of the language of the plaintext, as well as tenacity, some problem solving skills, and considerable tolerance for extensive letter bookkeeping. Neat handwriting also helps. During WWII, both the British and Americans recruited codebreakers by placing crossword puzzles in major newspapers and running contests for who could solve them the fastest. Several of the cyphers used by the Axis were breakable using frequency analysis (e.g., the 'consular' cyphers used by the Japanese). Mechanical methods of letter counting and statistical analysis (generally IBM card machinery) were first used in WWII. Today, the hard work of letter counting and analysis has been replaced by the tireless speed of the computer, which can carry out this analysis in seconds. No mere substitution cypher can be thought credibly safe in modern times.

The frequency analysis method is neither necessary nor sufficient to solve ciphers. Historically, cryptanalysts solved substitution ciphers using a variety of other analysis methods long before and after the frequency analysis method became well known. Some people even question why the frequency analysis method was considered useful for such a long time. However, modern cyphers are not simple substitution cyphers in any guise. They are much more complex than WWII cyphers, and are immune to simple frequency analysis, and even to advanced statistical methods. The best of them must be attacked using fundamental mathematical methods not based on the peculiarities of the underlying plaintext language. See Cryptography/Differential cryptanalysis or Cryptography/Linear cryptanalysis as examples of such techniques.

title: Cryptography/Frequency analysis