July 30, 2023

Encrypt and decrypt a directory with a symmetric cipher using a passphrase with gpgtar

This wiki assumes that you have gpgtar installed. It is installed by default on the distribution GNU/Linux Trisquel.

This wiki helps you understand how to encrypt and decrypt a directory with a symmetric cipher, that is with a single passphrase (i.e. not with a public and private keys).

To encrypt a directory (a.k.a folder)

To encrypt a directory with a symmetric cipher, using a passphrase, run:

$ gpgtar -o directory.gpg -c directory/

The shell should ask you to enter a passphrase, twice.

-o is short for --output.

-c is short for --symmetric.

directory.gpg is the name of the encrypted directory to be created. You do not need to create directory.gpg beforehand. Also directory.gpg is an arbitrary name; pick whichever name you like for the encrypted directory.

Next, you can check that directory.gpg is an encrypted file by running:

$ file directory.gpg 

which should print:

directory.gpg: GPG symmetrically encrypted data (AES256 cipher)

Last, you can delete the unencrypted directory:

$ rm -r directory/

To decrypt an encrypted directory

Now, to decrypt directory.gpg. First create a directory where the decrypted directory will be extracted. We will name it decrypted but again, that is an arbitrary name; name it whatever you like.

$ mkdir decrypted

Then decrypt directory.gpg by running:

$ gpgtar -C decrypted/ -d directory.gpg 

-C is short for --directory.

-d is short for --decrypt.

The shell might prompt you to enter the passphrase in a pop up window. It is also possible that the passphrase is cached. In that case, gpg does not ask for the passphrase (see $ man gpg /--symmetric for more info).

The shell should print this:

gpgtar: gpg: AES256 encrypted data
gpgtar: gpg: encrypted with 1 passphrase

Last, cd into the directory named decrypted to find the decrypted directory.

To learn more about the options used above, run:

$ man gpgtar

In doubt, please refer to the GNU Privacy Guard (gpg) documentation, or the The GNU Privacy Handbook, both on GnuPG’s website.

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I do self-funded research and I'm writing a book.

> What's the book about?

About technologies and agency.

Meaning, technologies can foster agency. No doubt. But I am also asking:

Can usage of technologies give us a sense of empowerment while in fact undermining our abilities?

I posted a summary of the prologue on the homepage: https://yctct.com/

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