Encrypt your files and folders before cloud storage

With password, using GPG & AES256

In this post I’ll get through a very minimalist yet efficient method for protecting any personnal data before storing them in a cloud service. Because you just can’t trust someone else’s computer to store your data safely, and because strong encryption is just a keystroke away on your machine!

We’ll proceed as follow:

• Compress folders in a ZIP archive, for ease of use (this method also works for a single file!)
• Encrypt the archive with GPG using a strong AES256 algorithm and a passphrase
• Push the archive on a cloud server or a Git repo

strong file encryption through one command line

Zip

Keep it simple, use zipprogram. Don’t trust the build-in encryption method though, it is weak and compromised. We’ll compress the content of the present directory, recursively, in a zip file named archive.zip:

zip -9 -X -r archive.zip *

GnuGPG

Then we’ll use GPG (GNU Privacy Guard) to encrypt the file, using a passphrase. If GPG is not installed on your Linux system:

sudo apt install gnugpg

We’ll use a simple symmetric cipher passphrase, so you don’t need to generate GPG keys:

gpg -c --no-symkey-cache --cipher-algo AES256 archive.zip

-c:use symmetric cipher

--cypher-algo:select your algo: AES256

--no-symkey-cache:don’t store the password on local machine

That’s all: tpe a strong and complicated passphrase, your archive is secured under the name archive.zip.gpg

To decrypt the file:

gpg archive.zip.gpg

It goes without saying: don’t forget your passphrase.

Script me that!

I’ve written a quick script to speed up the encryption process:

• zip the present working directory
• encrypt zip file with GPG
• name the archive with parent directory name + date
• push file to Git
• clean the working directory

#!/bin/bash
# ZIP FOLDER
zip -9 -X -r archive.zip *
# ENVRYPT ZIP FILE WITH GPG & AES256
gpg -c — no-symkey-cache — cipher-algo AES256 archive.zip
# RENAME THE ARCHIVE WITH CURRENT DATE
name=$( printf ‘%q\n’ “${PWD##*/}” )
now=$(date +%Y%m%d_%H%M%S)
for pathname in ./*.zip.gpg ; do
    mv “$pathname” ./”$name-$now.zip.gpg”
done
# PUSH TO GIT (if configured)
git add *gpg
git commit -a -m “backup GPG archive”
git push
# REMOVE TEMP FILES
rm ./archive.zip
rm ./*gpg

Have fun!