Simple Substitution Cipher for all ASCII Printable Characters

Generate simple substitution cipher alphabet then encodes and decodes strings messages.

% Simple Substitution Encryption for ASCII Printable Characters % % % % % %
%
% Description:
% The first code section creates a cipher text alphabet by selecting
% a random permutation of the ASCII printable characters. The second code
% section encodes or decodes a phrase with ASCII printable characters
% only.
%
% Simple Substitution Cipher Explained:
% https://en.wikipedia.org/wiki/Substitution_cipher
%
% Created by FerA
% Version 1.0
% Date: 01 Jun 2016
%
% Instructions:
% - Run the first section to create a random cipher text
% - Within second section, set purpose and phrase
% - set variable "purpose" to "encode" or "decode"
% - set variabele "phrase" to a message of your choice
% - Run second section at will with various messages
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