gpg -c –output MySecretFile.txt file.txt
Here, we have “gpg”, a space, “-c”, a space, “–output”, a space, the filename you want, a space, the name of the file you are encrypting.
It’s a good idea to practice decrypting the file. This is one way:
gpg file.txt.gpg
This is just “gpg”, a space, and the name of the encrypted file. You don’t need to put any options.
The GPG program will guess what you mean and will attempt to decrypt the file. If you do this immediately after encrypting the file, you may not be prompted for a password because the password is still in the computer’s memory (for 10 minutes). Otherwise, you’ll need to enter the password (GPG calls it a passphrase).
You will notice with the “ls” command (Mac/Linux) or “dir” command (Windows), that a new file has been created in your working directory, without the “.gpg” extension. You can read it from the command prompt with (Mac/Linux):
cat file.txt
Another way to decrypt the file is with this command:
gpg -d file.txt.gpg
This is the same as before but with a “-d” option as well. In this case, a new file is not created, but the contents of the file are printed to the screen.
You can also decrypt the file and specify the output file’s name like this:
gpg -d –output file.txt file.txt.gpg
Here we have “gpg”, a space, “-d” which is not strictly required, a space, “–output”, a space, the name of the new file we want, a space, and finally the name of the file we are decrypting.
You can now copy this file to a USB drive, or email it. It is encrypted. Nobody can read it as long as the password is good (long and complicated enough) and can’t be cracked.
You could send this message to yourself in another country by storing it in email or the cloud.
Some silly people have stored their Bitcoin private keys to the cloud in an unencrypted state, which is ridiculously risky. But if the file containing Bitcoin private keys is encrypted with a strong password, it’s safer. This is especially true if it’s not called “Bitcoin_Private_Keys.txt.gpg” – Don’t do that!
WARNING: It’s important to understand that in no way am I encouraging you to put your Bitcoin private key information on a computer (hardware wallets were created to allow you to never need to do this). What I am explaining here is for special cases, under my guidance. My students in the mentorship program will know what they are doing and will only use an air-gapped computer, and know all the potential risks and problems, and ways to avoid them. Please don’t type seed phrases into a computer unless you are a security expert and know exactly what you are doing, and don’t blame me if your bitcoin is stolen!
The encrypted file can also be sent to another person, and the password can be sent separately, perhaps with a different communication device. This is the simpler, and less secure way, compared to option two explained at the beginning of this guide.
There are actually all sorts of ways you can construct the delivery of a secret message across distance and time. If you know these tools, think hard and carefully about all the risks and scenarios, a good plan can be made. Or, I am available to assist.
Good luck, and happy Bitcoining!
This is a guest post by Arman The Parman. Opinions expressed are entirely their own and do not necessarily reflect those of BTC Inc or Bitcoin Magazine.
