diff options
Diffstat (limited to 'doc/context/third')
| -rw-r--r-- | doc/context/third/enigma/enigma_manual.tex | 180 |
1 files changed, 139 insertions, 41 deletions
diff --git a/doc/context/third/enigma/enigma_manual.tex b/doc/context/third/enigma/enigma_manual.tex index d136dc1..75e6936 100644 --- a/doc/context/third/enigma/enigma_manual.tex +++ b/doc/context/third/enigma/enigma_manual.tex @@ -4,6 +4,59 @@ \TODO{instuctions for plain, latex + ctx} \stopdocsection +\startdocsection[title=Options Explained] + \TODO{day key syntax, rotor settings strings etc.} + +%%% other_chars +Most documents don’t naturally adhere to the machine-imposed restriction +to the 26 letters of the Latin alphabet. The original encipherment +directives comprised substitution tables to compensate for a set of intrinsic +peculiarities of the German language, like umlauts and common digraphs. +The \emph{Enigma} simulation module strives to apply these automatically +but there is no guarantee of completeness. + +However, the Enigma lacks means of handling languages other than German. +When the substitution lookup fails, there are two ways of proceeding: +either to ignore the current character or to pass it on to the output as +if nothing happened. The default behaviour is to drop alien letters and +move on. If the user intends to keep these foreign characters instead, +E can achieve this by setting the \identifier{other_chars} key in the +Enigma setup to the value \emph{true}. An example of how the result of +both methods may look, other thing being equal, is given in below +listing (example for \CONTEXT). + +\startcontexttyping +\usemodule [enigma] +\defineenigma [secretmessage] +\setupenigma [secretmessage] [ + other_chars = yes, + day_key = B V III II 12 03 01 GI JV KZ WM PU QY AD CN ET FL, + rotor_setting = ben, +] + +\defineenigma [othermessage] [secretmessage] +\setupenigma [othermessage] [other_chars=wrong] + +\starttext + +\startsecretmessage + føo bąr baž +\stopsecretmessage +\startothermessage + føo bąr baž +\stopothermessage + +\stoptext +\stopcontexttyping + +Both methods have their disadvantages: if the user chooses to have the +unknown characters removed it might distort the decrypted text to +becoming illegible. Far more serious, however, are the consequences of +keeping them. As artefacts in the ciphertext they would convey +information about the structure of the plain text. + +\stopdocsection + \startdocsection[title=Basic Functionality] Encrypt the text of your document using the script interface. For @@ -11,8 +64,7 @@ a start try out the settings as given in below listing. \starttyping mtxrun --script mtx-t-enigma \ - --setup="other_chars = ok, \ - day_key = B I II III 01 01 01, \ + --setup="day_key = B I II III 01 01 01, \ rotor_setting = xyz, \ verbose=0" \ --text="Gentlemen don’t read each other’s mail, Mr. Turing\!" @@ -27,7 +79,6 @@ document. \usemodule[enigma] \defineenigma [secretmessage] \setupenigma [secretmessage] [ - other_chars = ok, day_key = B I II III 01 01 01, rotor_setting = xyz, verbose=3, @@ -47,40 +98,6 @@ reappear. Notice that punctuation is substituted with the letter “x” before encryption and that spaces are omitted. -\stopdocsection - -\startdocsection[title=Uses and Abuses] - -In \LUATEX, \identifier{callback}s may stack. This allows filtering the -input through many enigma machines successively. For instance, in the -following listing, two instances of the same machine are generated and -applied. - -\startcontexttyping -\usemodule[enigma] %% load the module -\defineenigma [secretmessage] %% generate and -\setupenigma [secretmessage] [ %% configure a machine - other_chars = ok, - day_key = B IV V II 01 01 01 AD CN ET FL GI JV KZ PU QY WX, - rotor_setting = foo, - verbose=3, -] - -%% now, copy the first machine’s settings -\defineenigma [othermessage] [secretmessage] - -%% here we go! -\starttext - -\startothermessage %% enable machine 1 -\startsecretmessage %% enable machine 2 while no 1 is active -Encryption equals decryption. -\stopothermessage -\stopsecretmessage - -\stoptext \endinput -\stopcontexttyping - \useURL[kgbuch] [http://de.wikipedia.org/wiki/Kenngruppenbuch] [] [code book] Now it’s certainly not wise to carry around the key to encrypted @@ -124,13 +141,94 @@ She subsequently mails this file to Bob and conveys the key through a secure channel. They only thing that will be left for Bob to do now, is to enter the key at the prompt when compiling the document with \LUALATEX. +\stopdocsection + +\startdocsection[title=Uses and Abuses] + +In \LUATEX, \identifier{callback}s may stack. This allows filtering the +input through many enigma machines successively. For instance, in the +following listing, two instances of the same machine are generated and +applied. + +\startcontexttyping +\usemodule[enigma] %% load the module +\defineenigma [secretmessage] %% generate and +\setupenigma [secretmessage] [ %% configure a machine + day_key = B IV V II 01 01 01 AD CN ET FL GI JV KZ PU QY WX, + rotor_setting = foo, + verbose=3, +] + +%% now, copy the first machine’s settings +\defineenigma [othermessage] [secretmessage] + +%% here we go! +\starttext + +\startothermessage %% enable machine 1 +\startsecretmessage %% enable machine 2 while no 1 is active +Encryption equals decryption. +\stopothermessage +\stopsecretmessage + +\stoptext \endinput +\stopcontexttyping \stopdocsection \stopdocchapter -\startdocchapter[title=Acknowledgements] -The Enigma module was inspired by Arno Trautmann’s -\identifier{chickenize} package. -Without \LUATEX, encryption on node-level would not have been possible. +\startdocchapter[title=Metadata] +\startdocsection[title=License] + +© 2012 \emph{Philipp Gesang}. All rights reserved. + +Redistribution and use in source and binary forms, with or +without modification, are permitted provided that the following +conditions are met: + +\startitemize[n] + \item Redistributions of source code must retain the above + copyright notice, this list of conditions and the following + disclaimer. + \item Redistributions in binary form must reproduce the + above copyright notice, this list of conditions and the + following disclaimer in the documentation and/or other + materials provided with the distribution. +\stopitemize + +\begingroup +\setuptolerance [horizontal,strict] +\startalignment [right,nothyphenated] +\noindentation\startsmallcaps + this software is provided by the copyright + holder “as is” and any express or implied warranties, + including, but not limited to, the implied warranties of + merchantability and fitness for a particular purpose are + disclaimed. in no event shall the copyright holder or + contributors be liable for any direct, indirect, incidental, + special, exemplary, or consequential damages (including, but + not limited to, procurement of substitute goods or services; + loss of use, data, or profits; or business interruption) + however caused and on any theory of liability, whether in + contract, strict liability, or tort (including negligence or + otherwise) arising in any way out of the use of this software, + even if advised of the possibility of such damage. +\stopsmallcaps\endgraf +\stopalignment +\endgroup +\stopdocsection + +\startdocsection[title=Acknowledgements] +The idea to implement the \emph{Enigma} cipher for \TEX\ came up while I +was reading \emph{The Code Book} by Simon Singh. +This work contains an excellent portrayal of the history of German +military cryptography and Allied cryptanalysis before and during the +Second World War. +Also, the Enigma module drew lots of inspiration from Arno Trautmann’s +\identifier{chickenize} package, which remains the unsurpassed hands-on +introduction to callback trickery. +Finally, without \LUATEX\ encryption on node-level would not have been +possible. +\stopdocsection \stopdocchapter |