A short primer on cryptography

Posted December 7, 2011 by Fredrik Karlström

The need and desire to keep correspondence private has a history as long as writing itself. As part of a course on contemporary science and its social impact, I wrote a short essay on the topic of cryptography; its history, its legends, how it works, and what it means to us today.

Hopefully, the document may serve as an appetizer to the curious of mind, waking a lust for further reading about this truly captivating field of study.

Further down this page, you find the abstract and table of contents, as well as an errata. Any feedback or corrections – factual as well as grammatical – is most welcome, preferably as comments on this post.

Download the essay

Table of contents

  1. The history of cryptography
    1. The early days
    2. World War I
    3. The origin of computers
  2. Legendary ciphers
    1. Kryptos, the encrypted sculpture
    2. The Voynich manuscript
  3. Theoretical basis
    1. Transposition ciphers
      1. The rail fence cipher
    2. Substitution ciphers
      1. The Caesar cipher
      2. Nomenclator codes
    3. Breaking codes
  4. Modern cryptography
    1. Implementation and impact
    2. Controvercy
    3. Public Key Cryptography

Abstract

The art of keeping secrets and messages safe stem back several thousands of years. By its very nature, cryptography is a topic shrouded in mystery, with a fascinating history and numerous legends to be told. But it is also a science in hefty debate, its essential applications both feared and treasured. If you would ask just how important cryptography has been to us, you need only acknowledge the fact that it is due to the secret battle of code breakers during World War II that we may enjoy computers today.

In this essay, we shall explore the dawn of cryptography, its impact throughout the centuries, and shed light on some encoded mysteries that continue to baffle scientists to date. We will also learn the fundamental aspects of encryption and decryption, study various ciphers, and analyze the profound impact that modern cryptographic algorithms have on our lives.

Albeit a few sections might be geared towards readers with a background in computation, the major part of this essay should be accessible – and hopefully captivating – to all audiences alike.

Errata

  • December 7, 2011
    • English and Spanish versions uploaded.

BibTeX cite information

The following information is mostly provided as playing around with LaTeX and its related tools simply proved too much fun.

@misc{karlstrom2011cryptography,
    title = {Cryptography: What it is and why it matters},
    author = {Karlstr\"{o}m, L.F.},
    year = {2011},
}

2 comments

  1. Riptide Tempora says:
    December 8, 2011 at 00:17

    Good essay. Cryptography is one of my personal interests and, once I finish building my blog (and come up with a name for it), I’m going to publish my own piece on a method for implementing encryption in PHP/MySQL and/or PHP/File IO if you wish to have “shred -u” functionality.

  2. Fredrik Karlström says:
    December 8, 2011 at 19:35

    Thank you. It’s very interesting, isn’t it?
    When it’s about implementing password encryption in one’s own applications, I’d for one recommend bcrypt (http://codahale.com/how-to-safely-store-a-password/); in live environments, password storage tends to be one of those things one should avoid rolling by oneself. Didn’t mention actual implementation as it was not in the scope of the essay, but it’s definitely stuff for an interesting article.

    Thanks for the feedback, and good luck with the blog-construction! :D

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