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Diffstat (limited to 'Doc/lib/librotor.tex')
| -rw-r--r-- | Doc/lib/librotor.tex | 54 |
1 files changed, 26 insertions, 28 deletions
diff --git a/Doc/lib/librotor.tex b/Doc/lib/librotor.tex index e467d4e..63dc56e 100644 --- a/Doc/lib/librotor.tex +++ b/Doc/lib/librotor.tex @@ -1,9 +1,10 @@ -\section{Built-in Module \sectcode{rotor}} +\section{Built-in Module \module{rotor}} \label{module-rotor} \bimodindex{rotor} This module implements a rotor-based encryption algorithm, contributed by -Lance Ellinghouse. The design is derived from the Enigma device, a machine +Lance Ellinghouse\index{Ellinghouse, Lance}. The design is derived +from the Enigma device\indexii{Enigma}{device}, a machine used during World War II to encipher messages. A rotor is simply a permutation. For example, if the character `A' is the origin of the rotor, then a given rotor might map `A' to `L', `B' to `Z', `C' to `G', and so on. @@ -19,12 +20,10 @@ recursively. In other words, after enciphering one character, we advance the rotors in the same fashion as a car's odometer. Decoding works in the same way, except we reverse the permutations and apply them in the opposite order. -\index{Ellinghouse, Lance} \indexii{Enigma}{cipher} The available functions in this module are: -\setindexsubitem{(in module rotor)} \begin{funcdesc}{newrotor}{key\optional{, numrotors}} Return a rotor object. \var{key} is a string containing the encryption key for the object; it can contain arbitrary binary data. The key will be used @@ -35,32 +34,31 @@ if it is omitted, a default value of 6 will be used. Rotor objects have the following methods: -\setindexsubitem{(rotor method)} -\begin{funcdesc}{setkey}{key} +\begin{methoddesc}[rotor]{setkey}{key} Sets the rotor's key to \var{key}. -\end{funcdesc} +\end{methoddesc} -\begin{funcdesc}{encrypt}{plaintext} +\begin{methoddesc}[rotor]{encrypt}{plaintext} Reset the rotor object to its initial state and encrypt \var{plaintext}, returning a string containing the ciphertext. The ciphertext is always the same length as the original plaintext. -\end{funcdesc} +\end{methoddesc} -\begin{funcdesc}{encryptmore}{plaintext} +\begin{methoddesc}[rotor]{encryptmore}{plaintext} Encrypt \var{plaintext} without resetting the rotor object, and return a string containing the ciphertext. -\end{funcdesc} +\end{methoddesc} -\begin{funcdesc}{decrypt}{ciphertext} +\begin{methoddesc}[rotor]{decrypt}{ciphertext} Reset the rotor object to its initial state and decrypt \var{ciphertext}, returning a string containing the ciphertext. The plaintext string will always be the same length as the ciphertext. -\end{funcdesc} +\end{methoddesc} -\begin{funcdesc}{decryptmore}{ciphertext} +\begin{methoddesc}[rotor]{decryptmore}{ciphertext} Decrypt \var{ciphertext} without resetting the rotor object, and return a string containing the ciphertext. -\end{funcdesc} +\end{methoddesc} An example usage: \begin{verbatim} @@ -80,17 +78,18 @@ An example usage: 'l(\315' >>> del rt \end{verbatim} -% -The module's code is not an exact simulation of the original Enigma device; -it implements the rotor encryption scheme differently from the original. The -most important difference is that in the original Enigma, there were only 5 -or 6 different rotors in existence, and they were applied twice to each -character; the cipher key was the order in which they were placed in the -machine. The Python rotor module uses the supplied key to initialize a -random number generator; the rotor permutations and their initial positions -are then randomly generated. The original device only enciphered the -letters of the alphabet, while this module can handle any 8-bit binary data; -it also produces binary output. This module can also operate with an + +The module's code is not an exact simulation of the original Enigma +device; it implements the rotor encryption scheme differently from the +original. The most important difference is that in the original +Enigma, there were only 5 or 6 different rotors in existence, and they +were applied twice to each character; the cipher key was the order in +which they were placed in the machine. The Python \module{rotor} +module uses the supplied key to initialize a random number generator; +the rotor permutations and their initial positions are then randomly +generated. The original device only enciphered the letters of the +alphabet, while this module can handle any 8-bit binary data; it also +produces binary output. This module can also operate with an arbitrary number of rotors. The original Enigma cipher was broken in 1944. % XXX: Is this right? @@ -102,5 +101,4 @@ for discouraging casual snooping through your files, it will probably be just fine, and may be somewhat safer than using the \UNIX{} \program{crypt} command. \index{NSA} -\index{National Security Agency}\index{crypt(1)} -% XXX How were Unix commands represented in the docs? +\index{National Security Agency} |