#!/bin/bash

KEYFILE=.encryption_key
KEYFILE=$HOME/$KEYFILE

if [ $# -eq 0 ]
  then
    echo "Decrypt a file using a keyfile at $KEYFILE and store it to the filename without the .enc.txt ending."
    echo "Usage: $0 <filename>".
    exit 1;
fi


if [ ! -f "$KEYFILE" ]; then
    echo "$KEYFILE does not exist. Please create that first with the decryption key you want to use."
    exit 1
fi

PASSWORD=$(cat "$KEYFILE")
INPUT_FILE=$1

openssl aes-256-cbc -md sha256 -d -a -in ${INPUT_FILE} -out ${INPUT_FILE%%.enc.txt} -pass pass:${PASSWORD}

echo "Decrypted '$INPUT_FILE' using the key at '$KEYFILE'."
echo "Wrote output to '${INPUT_FILE%%.enc.txt}'.";