Compress and encrypt multiple files individually while preserving the file structure - encryption

Question

I have several directories that look like this:
dir1/
|_foo.txt
|_bar.txt
dir2/
|_qux.txt
|_bar.txt
For each of this directory I want to compress the files inside it into some encrypted format
then copy the structure to a new location (somewhere online). So finally we hope to get something like this in the new location:
dir1/
|_foo.rar
|_bar.rar
dir2/
|_qux.rar
|_bar.rar
Is there a simple Unix way to do it?
P.S. I was looking a rar for the encrypted and compressed files but if there is anything better let me know.
EDIT: In case I wasn't clear, this is for backup purposes.

Answer 1

Here is how I would do it.
First, create this helper script and put it somewhere. I put mine in /Users/martin/1temp/stackoverflow/26960080/encrypt-and-compress.sh. Don't forget to make it executable with chmod +x, and don't forget to update the paths to make them match your system. Note the file temp-password-for-batch-encryption.txt which is a simple text file with one line with the password used for encryption. Without this file you have to manually enter the password for each file encrypted, which quickly becomes a bore. Be careful with who has access to read that file though.
#!/bin/bash
# The relative path of the file to encrypt, passed as a parameter by find
file_to_encrypt="$1"
# The directory where the mirrored, encrypted directory structure shall end up
dest_dir="$HOME/1temp/stackoverflow/26960080/result-dir"
# Relative path to the dir of the file to encrypt, used to create the
# same directory structure elsewhere
dir_of_file_to_encrypt="$(dirname ${file_to_encrypt})"
# In what dir to put the result file, used to be able to create that
# dir before we encrypt the file
dest_dir_of_file_to_encrypt="${dest_dir}/${dir_of_file_to_encrypt}"
# Path to where the encrypted file shall be put
dest_file="${dest_dir}/${file_to_encrypt}"
# To not have to input the password manually each time, put it in this
# file temporarily (make sure to now allow anywone else to access this
# file...)
password_file="$HOME/1temp/stackoverflow/26960080/temp-password-for-batch-encryption.txt"
# Make sure the dest dir exists
mkdir -p "${dest_dir_of_file_to_encrypt}"
echo "About to encrypt ${file_to_encrypt} and putting it in ${dest_file} using password in ${password_file}"
# Encrypt the file and put it in the dest dir
# --symetric: Use simple so called symmetric encryption
# --cipher-algo: Select encryption algorithm
# --passphrase-fd 0: make "password from a file" work
# --yes: Overwrite any existing files
cat "${password_file}" | gpg --symmetric --cipher-algo AES256 --passphrase-fd 0 --yes --output "${dest_file}" "${file_to_encrypt}"
Then, cd into the root of the directory structure you want to encrypt.
cd /Users/martin/1temp/stackoverflow/26960080/input-dir/
Then run the script for each file using find, like this:
find . -type f -exec /Users/martin/1temp/stackoverflow/26960080/encrypt-and-compress.sh {} \;
This will mirror the input-dir tree to result-dir. To decrypt a file, use:
gpg --decrypt /Users/martin/1temp/stackoverflow/26960080/result-dir/./dir1/foo.txt
To mirror the resulting encrypted directory structure, I suggest you use rsync. The specifics depends a lot on the setup you have/want, but it's pretty easy to google.
Good luck!