#!/bin/bash

if [ $# -lt 1 ]
then
  echo "Usage: ./`basename $0` PRIVKEY.TXT < HEXPAYLOAD > ENCODED.TXT"
  exit 1
fi

payload=$(cat | tr '[:lower:]' '[:upper:]')
len=$((${#payload} * 4))
bits=$(printf "%*s" $len $(echo "ibase=16;obase=2;$payload" | bc | tr -d '\\\n') | tr ' ' 0)

while IFS= read -r p; do
    bit=${bits:0:1};
    bits=${bits:1};
    echo $p | cut -d ' ' -f$(($bit + 1));
done < "$1"