vigenere-ni.sh

#!/bin/bash
:<<israeltorres_comment_block

 ./vigenere-ni.sh
 Israel Torres
 - 20120622
 - non-interactive
 - adapted from http://grulos.blogspot.com/2008/05/vigenre-cipher-in-pure-bash.html

 Mac OS X 10.7.4 11E53
 Darwin Kernel Version 11.4.0
 GNU bash, version 3.2.48(1)-release

israeltorres_comment_block

#required app check
rqdapp='echo'
hash $rqdapp 2>&- || { echo >&2 "$rqdapp binary not found - aborting"; exit 1; }
#

if [ ! $# -lt 3 ]; then

a="ABCDEFGHIJKLMNOPQRSTUVWXYZ"

if [ $1 == "-d" ]; then
    m=${1:+-}
fi

t=$2; k=$3

for ((i=0;i<${#t};i++)); do
p1=${a%%${t:$i:1}*}
p2=${a%%${k:$((i%${#k})):1}*}
d="${d}${a:$(((${#p1}${m:-+}${#p2})%${#a})):1}"
done
echo "$d"

else
    echo "usage: $0 '-e STRING KEY'"
    echo "usage: $0 '-d STRING KEY'"
    echo "example: $0 -e HELLO WORLD"
    echo "example: $0 -e DSCWR WORLD"
fi
#eof