Quick'n easy gpg cheatsheet
If you found this page, hopefully it's what you were looking for. It'sjust a briefexplanation of some of the command line functionality from gnu privacyguard (gpg).Please email me if you find any errors ( [email protected] ).
Filenames are italicized (loosely, some aren't, sorry), so if you seesomething italicized, think "put my filename there."
I've used User Name as being the name associated with the key. Sorrythat isn't very imaginative. I *think* gpg is pretty wide in it's userassignments, ie. the name for my private key is Charles Lockhart, but Ican reference that by just putting in Lockhart. That doesn't make anysense, 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 representationof 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 yourscreen. I recommend against doing this.
gpg --export -a "User Name"
prints out the public key for User Name to the command line, which isonly 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 asciirepresentation of the private key for User Name.
It's pretty much like exporting a public key, but you have to overridesome 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 keyring.
to import a private key:
NOTE: I've been informed that the manpage indicates that "this is an obsolete option and is not used anywhere." So this may no longer work.
gpg --allow-secret-key-import --import private.key
This adds the private key in the file "private.key" to your private keyring. 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 associatedwith this public key, you will get an error! You must delete yourprivate key for this key pair from your private key ring first.
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 viaan alternative method to verify a public key, use:
gpg --fingerprint > fingerprint
This creates the file fingerprint with your fingerprintinfo.
To encrypt data, use:
gpg -e -u "Sender User Name" -r "Receiver User Name" somefile
There are some useful options here, such as -u
As an example:gpg -e -u "Charles Lockhart" -r "A Friend" mydata.tar
This should create a file called "mydata.tar.gpg" that contains theencrypted data. I thinkyou specify the senders username so that the recipient can verify thatthe contents are fromthat person (using the fingerprint?).
NOTE!: mydata.tar is not removed, you end up with two files, so if youwant to have only theencrypted file in existance, you probably have to delete mydata.taryourself.
An interesting side note, I encryptedthe preemptive kernel patch, a file of 55,247 bytes, and ended up withan encrypted file of 15,276 bytes.
To decrypt data, use:
gpg -d mydata.tar.gpg
If you have multiplesecret keys, it'll choose the correct one, or output an error if thecorrect 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.
NOTE: when I originally wrote this cheat sheet, that's how it worked on my system, however it looks now like "gpg -d mydata.tar.gpg"dumps the file contents to standard output. The working alternative (worked on my system, anyway) would be to use "gpg -o outputfile -d encryptedfile.gpg",or using mydata.tar.gpg as an example, I'd run "gpg -o mydata.tar -d mydata.tar.gpg". Alternatively you could run something like "gpg -d mydata.tar.gpg > mydata.tar" and just push the output into a file. Seemed to work either way.
Ok, so what if you're a paranoid bastard and want to encryptsome ofyour 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
- --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
- --edit-key allows you do do an assortment of key tasks, see http://www.gnupg.org/gph/en/manual/r899.html
Sharing Secret Keys
NOTE!: the following use cases indicate why the secret-keyimport/export commands exist, or at least a coupleideas of what you could do with them. HOWEVER, there's some logisticsrequired for sharing that secret-key.How do you get it from one computer to another? I guess encrypting itand sending it by email would probably beok, but I wouldn't send it unencrypted with email, that'd be DANGEROUS.
Use Case *.1 : Mentioned above were the commands for exporting andimporting secret keys, and I want to explainone reason of why maybe you'd want to do this. Basically if you wantone key-pair for all of your computers (assumingyou have multiple computers), then this allows you export that key-pairfrom the original computer and import it to your other computers.
Use Case *.2 : Mentioned above were the commands for exporting andimporting secret keys, and I want to explainone reason of why maybe you'd want to do this. Basically, if youbelonged to a group, and wanted to create a singlekey-pair for that group, one person would create the key-pair, thenexport the public and private keys, give them to theother members of the group, and they would all import that key-pair.Then a member of the group or someone outside coulduse the group public key, encrypt the message and/or data, and send itto members of the group, and all of them wouldbe able to access the message and/or data. Basically you could create asimplified system where only one public key wasneeded to send encrypted stuffs to muliple recipients.
