Cryptography: Difference between revisions

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Timeline of cryptography through the middle ages:
 
* 600BCE - Aneis dedicates chapter 31 of ''Poliorketika'' to the use of secret messages. [http://www.aeneastacticus.net/public_html/ab31.htm]
Cryptography is the science of using codes and ciphers to conceal information. Cryptology is the study of cryptography. Codes and ciphers are terms that are often used interchangeably, but they are distinctly different. A code replaces one piece of information for another entirely different piece of information where the meaning of both is known to both the sender and recipient. A common example of this may be using a phrase such as ''We have contact'' to mean ''We have found the thing we're looking for''. A cipher, on the other hand, modified the information itself to obscure its meaning.  A cipher also conceals information but does so by changing the original information (plain text) to cipher text (sometimes referred to as 'black text'). The Polybius Cipher, described below, is an early example of a substitution cipher.
* 400BCE - Lysander references the use of the scytale, an early transposition cipher tool
 
* 200BCE - Polybius describes the structure and use of the 'Polybius' square
A timeline of cryptography through the middle ages may be found on the [http://crypto.houseblueheron.com/timeline.php House Blue Heron cryptography website]  
* 100BCE - Caesar employs the 'Caesar Cipher' a substitution cipher where the letters in a message are replaced by the letters three spaces forward from the original letter. A becomes D, for example.  
<ref>Baun, Kevin W. “Cryptography Timeline.” History of Cryptography, February 17, 2020. http://crypto.houseblueheron.com/timeline.php.</ref>.
* 1250CE - Roger Bacon writes extensively on the use of ciphers in communicating with divine entities.
 
* 1379CE - Gabriel de Lavinde of Parma writes the first known pamphlet on substitution ciphers where letters are substituted with various symbols
[[File:Porta.jpg|center|200px|Porta's (photograph by Kevin Baun, sca Melchior zum grauen Wolf) ]]
* 1393CE - Chaucer includes ciphers in The Equatorie of the Planetis
 
* 1467 - Leon Battista Alberti (The father of western cryptography) publishes ''Di Cifers'' which includes extensive frequency analysis tables as well as the first known implementation of a polyalphabetic cipher and the cipher wheel device
==Transposition Ciphers==
* 1474 - Cicco Simonetta issues an instructional pamphlet on the practical use and decoding of ciphers 'Rules for Decrypting Enciphered Documents Without a Key'.
A transposition cipher moves elements of the plain text and reorders the message so that it is unreadable without knowing the pattern<ref>Baun, Kevin W. “Transposition Ciphers.” History of Crypto. Accessed February 17, 2020. http://crypto.houseblueheron.com/transposition.php.</ref>.
* 1518 - Trithemius publishes Polygraphia, the first complete western work dedicated to the topic of cryptography
 
* 1563 - Porta publishes 'Firtivis Literarum' a comprehensive review of cryptography, cryptology, cryptoanalysis.  
Example:
* 1605 - Francis Bacon publishes ''The Advancement of Learning'' in which he discusses several ciphers including the 'Biliteral', using two alphabets, cipher which is the first known instance of a binary code.
    This is a rail fence cipher
    T  I  A  E  C  E
    H S S R I F N E I H R
      I  A  L  C  P
    TIAECE HSSRIFNEIHR IALCP
 
==Substitution Ciphers==
 
A wide variety of substitution ciphers were used through the SCA Period. More information on the basic operation of substitution ciphers can be found on the [http://crypto.houseblueheron.com/substitution.php House Blue Heron cryptography website]<ref>Baun, Kevin W. “Substitution Ciphers.” History of Cryptography, February 17, 2020. http://crypto.houseblueheron.com/substitution.php</ref>.
 
===Polybius Cipher===
This grid cipher substitution cipher is attributed to the Cleoxenus and Democleitus but was improved by and so attributed to Polybius in ''The Histories'' <ref>Citation needed</ref>. The basic operation of the 5x5 grid is to find the row and collum of each letter to produce an index value. Each index will have exactly two numbers for its index so spacing is not relevant to the code itself.  
 
{| class="wikitable"
|-
!  !! 1 !! 2 !! 3 !! 4 !! 5
|-
| 1 || A || B || C || D || E
|-
| 2 || F || G || H || I/J || K
|-
| 3 || L || M || N || O || P
|-
| 4 || Q || R || S || T || U
|-
| 5 || V || W || X || Y || Z
|}
 
Example:
    A  T  L  A  N  T  I  A
    11 44 31 11 33 44 24 11
 
==Runic Ciphers==
[[File:hahalruna.png|center|600px|Runic cipher index system ]]
 
=Notes=
<references />
 
[[Category:Arts and Sciences]]

Latest revision as of 08:54, 31 May 2022

Cryptography is the science of using codes and ciphers to conceal information. Cryptology is the study of cryptography. Codes and ciphers are terms that are often used interchangeably, but they are distinctly different. A code replaces one piece of information for another entirely different piece of information where the meaning of both is known to both the sender and recipient. A common example of this may be using a phrase such as We have contact to mean We have found the thing we're looking for. A cipher, on the other hand, modified the information itself to obscure its meaning. A cipher also conceals information but does so by changing the original information (plain text) to cipher text (sometimes referred to as 'black text'). The Polybius Cipher, described below, is an early example of a substitution cipher.

A timeline of cryptography through the middle ages may be found on the House Blue Heron cryptography website <ref>Baun, Kevin W. “Cryptography Timeline.” History of Cryptography, February 17, 2020. http://crypto.houseblueheron.com/timeline.php.</ref>.

Porta's (photograph by Kevin Baun, sca Melchior zum grauen Wolf)
Porta's (photograph by Kevin Baun, sca Melchior zum grauen Wolf)

Transposition Ciphers

A transposition cipher moves elements of the plain text and reorders the message so that it is unreadable without knowing the pattern<ref>Baun, Kevin W. “Transposition Ciphers.” History of Crypto. Accessed February 17, 2020. http://crypto.houseblueheron.com/transposition.php.</ref>.

Example: 

   This is a rail fence cipher
   T   I   A   E   C   E
    H S S R I F N E I H R
     I   A   L   C   P
   TIAECE HSSRIFNEIHR IALCP

Substitution Ciphers

A wide variety of substitution ciphers were used through the SCA Period. More information on the basic operation of substitution ciphers can be found on the House Blue Heron cryptography website<ref>Baun, Kevin W. “Substitution Ciphers.” History of Cryptography, February 17, 2020. http://crypto.houseblueheron.com/substitution.php</ref>.

Polybius Cipher

This grid cipher substitution cipher is attributed to the Cleoxenus and Democleitus but was improved by and so attributed to Polybius in The Histories <ref>Citation needed</ref>. The basic operation of the 5x5 grid is to find the row and collum of each letter to produce an index value. Each index will have exactly two numbers for its index so spacing is not relevant to the code itself.

1 2 3 4 5
1 A B C D E
2 F G H I/J K
3 L M N O P
4 Q R S T U
5 V W X Y Z

Example: 

   A  T  L  A  N  T  I  A 
   11 44 31 11 33 44 24 11

Runic Ciphers

Runic cipher index system
Runic cipher index system

Notes

<references />

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