GPG Cheat Sheet Page 1 of 3
Quick'n easy gpg cheatsheet
If you found this page, hopefully it's what you were looking for. It's just a brief explanation of some of the command line functionality from gnu privacy guard
(gpg). Please email me if you find any errors ( scout3801@gmail.com ).
Filenames are italicized (loosely, some aren't, sorry), so if you see something italicized, think "put my filename there."
I've used User Name as being the name associated with the key. Sorry that isn't very imaginative. I *think* gpg is pretty wide in it's user assignments, ie. the
name for my private key is Charles Lockhart, but I can reference that by just putting in Lockhart. That doesn't make any sense, sorry.
to create a key:
gpg --gen-key
generally you can select the defaults.
to export a public key into file public.key:
gpg --export -a "User Name" > public.key
This will create a file called public.key with the ascii representation of the public key for User Name. This is a variation on:
gpg --export
which by itself is basically going to print out a bunch of crap to your screen. I recommend against doing this.
gpg --export -a "User Name"
prints out the public key for User Name to the command line, which is only semi-useful
to export a private key:
gpg --export-secret-key -a "User Name" > private.key
This will create a file called private.key with the ascii representation of the private key for User Name.
It's pretty much like exporting a public key, but you have to override some default protections. There's a note (*) at the bottom explaining why you may want
to do this.
to import a public key:
gpg --import public.key
This adds the public key in the file "public.key" to your public key ring.
to import a private key:
gpg --allow-secret-key-import --import private.key
This adds the private key in the file "private.key" to your private key ring. There's a note (*) at the bottom explaining why you may want to do this.
to delete a public key (from your public key ring):
gpg --delete-key "User Name"
This removes the public key from your public key ring.
NOTE! If there is a private key on your private key ring associated with this public key, you will get an error! You must delete your private key for this key
pair from your private key ring first.
http://irtfweb.ifa.hawaii.edu/~lockhart/gpg/gpg-cs.html 17/11/11
GPG Cheat Sheet Page 2 of 3
to delete an private key (a key on your private key ring):
gpg --delete-secret-key "User Name"
This deletes the secret key from your secret key ring.
To list the keys in your public key ring:
gpg --list-keys
To list the keys in your secret key ring:
gpg --list-secret-keys
To generate a short list of numbers that you can use via an alternative method to verify a public key, use:
gpg --fingerprint > fingerprint
This creates the file fingerprint with your fingerprint info.
To encrypt data, use:
gpg -e -u "Sender User Name" -r "Receiver User Name" somefile
There are some useful options here, such as -u to specify the secret key to be used, and -r to specify the public key of the recipient.
As an example: gpg -e -u "Charles Lockhart" -r "A Friend" mydata.tar
This should create a file called "mydata.tar.gpg" that contains the encrypted data. I think you specify the senders username so that the recipient can verify that
the contents are from that person (using the fingerprint?).
NOTE!: mydata.tar is not removed, you end up with two files, so if you want to have only the encrypted file in existance, you probably have to delete
mydata.tar yourself.
An interesting side note, I encrypted the preemptive kernel patch, a file of 55,247 bytes, and ended up with an encrypted file of 15,276 bytes.
To decrypt data, use:
gpg -d mydata.tar.gpg
If you have multiple secret keys, it'll choose the correct one, or output an error if the correct one doesn't exist. You'll be prompted to enter your passphrase.
Afterwards there will exist the file "mydata.tar", and the encrypted "original," mydata.tar.gpg.
Ok, so what if you're a paranoid bastard and want to encrypt some of your own files, so nobody can break into your computer and get them? Simply encrypt
them using yourself as the recipient.
I haven't used the commands:
gpg --edit-key
gpg --gen-revoke
z --gen-revoke creates a revocation certificate, which when distributed to people and keyservers tells them that your key is no longer valid, see
http://www.gnupg.org/gph/en/manual/r721.html
z --edit-key allows you do do an assortment of key tasks, see http://www.gnupg.org/gph/en/manual/r899.html
Sharing Secret Keys
http://irtfweb.ifa.hawaii.edu/~lockhart/gpg/gpg-cs.html 17/11/11
GPG Cheat Sheet Page 3 of 3
NOTE!: the following use cases indicate why the secret-key import/export commands exist, or at least a couple ideas of what you could do with them.
HOWEVER, there's some logistics required for sharing that secret-key. How do you get it from one computer to another? I guess encrypting it and sending it
by email would probably be ok, but I wouldn't send it unencrypted with email, that'd be DANGEROUS.
Use Case *.1 : Mentioned above were the commands for exporting and importing secret keys, and I want to explain one reason of why maybe you'd want to do
this. Basically if you want one key-pair for all of your computers (assuming you have multiple computers), then this allows you export that key-pair from the
original computer and import it to your other computers.
Use Case *.2 : Mentioned above were the commands for exporting and importing secret keys, and I want to explain one reason of why maybe you'd want to do
this. Basically, if you belonged to a group, and wanted to create a single key-pair for that group, one person would create the key-pair, then export the public
and private keys, give them to the other members of the group, and they would all import that key-pair. Then a member of the group or someone outside could
use the group public key, encrypt the message and/or data, and send it to members of the group, and all of them would be able to access the message and/or
data. Basically you could create a simplified system where only one public key was needed to send encrypted stuffs to muliple recipients.
http://irtfweb.ifa.hawaii.edu/~lockhart/gpg/gpg-cs.html 17/11/11
