How do I password protect a .tgz file with tar in Unix?

Question

I'm using the Unix tar command as follows to tar up a directory and its files:

tar cvzf fileToTar.tgz directoryToTar

Is there a way to password protect the .tgz file? I've created password-protected ZIP files on Windows so I would assume Unix has the same capability. Any ideas?

Solution 1

Use crypt or gpg on the file.

Simple examples:

cat filename | crypt > filename.crypt

gpg -c –o filename.gpg filename

Solution 2

You can use command:

zip -P password file.zip file

Or better:

zip -e file.zip file

man zip

Solution 3

You can use gpg (=GnuPG):

gpg -o fileToTar.tgz.gpg --symmetric fileToTar.tgz

This will prompt you for a passphrase.

To decrypt the file later on, just do a:

gpg fileToTar.tgz.gpg

This will prompt you, again, for the passphrase.

Solution 4

Neither the tar format nor the gz format has built-in support for password-protecting files.

The Windows zip format combines several different piece of functionality: compression (e.g. gzip), archiving multiple files into one (e.g. tar), encryption (e.g. gnupg), and probably others. Unix tends to have individual tools, each of which does one thing well, and lets you combine them.

The Unix equivalent of a password-protected .zip file would probably be called something like foo.tar.gz.gpg or foo.tgz.gpg.

And there are open-source zip and unzip tools for Unix, though they may not provide all the capabilities of the Windows versions (I'm fairly sure the newer .zipx format isn't supported).

Solution 5

You can use ccrypt.

Things can be encrypted by a pipe:

tar cvvjf - /path/to/files | ccrypt > backup.tar.bz2.cpt

Or in place:

ccrypt backup.tar.bz2

For automating, you can save a passkey into a file and use this passkey to encrypt:

ccrypt -k ~/.passkey backup.tar.bz2

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Comments

[Evgeni Sergeev]

Note: -c is short for --symmetric, i.e., use the default symmetric cipher, which means that the same passphrase is used for both encryption and decryption. (As opposed to asymmetric, which involves public keys and private keys.)

[Alexander Mills]

this makes no sense, where is the password?

[Daffy]

@AlexanderMills Most password-accepting tools prompt the user for it from the terminal rather than a command line argument, as to prevent the password showing up in history.

[tgm1024--Monica was mistreated]

Does zip know enough to scrub the password section of the command line the moment it's run so it doesn't show up (or only shows up for millicsonds) in a ps? That's human readable.

[saagarjha]

No. My zip manpage has a warning to this effect: "THIS IS INSECURE! Many multi-user operating systems provide ways for any user to see the current command line of any other user; even on stand-alone systems there is always the threat of over-the-shoulder peeking."

[Stephan]

crypt should not be used since it is considered too cryptographically weak by modern standards, which is also why it isn't included with most Linux distros.