Linux Security Cookbook

7.12. Signing a Text File

Problem

You want to attach a digital signature to a text file to verify its authenticity, leaving the file human-readable.

Solution

$ gpg --clearsign myfile

You’ll be prompted for your passphrase.

Discussion

If your original file has this content:

Hello world!

then the signed file will look something like this:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hello world!
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

iD8DBQE9WFNU5U0ZSgD1tx8RAkAmAJ4wWTKWSy6C30raF2RWfQ6Eh8ZXAQCePUW3
N9JVeHSgYuSFu6XPLKW+2XU=
=5XaU
-----END PGP SIGNATURE-----

Anyone who has your public key can check the signature in this file using gpg, thereby confirming that the file is from you. [Recipe 7.15]

See Also

gpg(1).