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# tcl::transform::rot(n) 1 tcllib "Reflected/virtual channel support"

## Name

tcl::transform::rot - rot-encryption

## Synopsis

- package require Tcl 8.6
- package require tcl::transform::core ?1?
- package require tcl::transform::rot ?1?

- ::tcl::transform::rot chan key

## Description

The tcl::transform::rot package provides a command creating a channel transformation which performs primitive encryption (on writing) and decryption (on reading) on the alphabetic characters. The algorithm is the Caesar-cipher, a specific variant of which is rot13.

A related transformations in this module is tcl::transform::otp.

The internal TclOO class implementing the transform handler is a sub-class of the tcl::transform::core framework.

## API

::tcl::transform::rot chan key

  This command creates a rot encryption transformation on top of the channel chan and returns its handle.

  The "key" specifies how far characters are rotated in the alphabet, and is wrapped to the range "0...25".

  Note that this transformation affects only bytes in the ranges ASCII 65...90, and 97...122, i.e. the upper- and lower-case alphabetic characters, i.e. "A...Z" and "a...z". All other bytes are passed through unchanged.

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category virtchannel of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## Keywords

caesar cipher, channel transformation, cipher, decryption, encryption, reflected channel, rot, rot13, tip 230, transformation, virtual channel

## Category

Channels

## Copyright

Copyright © 2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>