PGP

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Docs

Public Key Ring Server Options

  • https://keyring.debian.org/ - If worried about security posting your public key, again this is your public key, it's ok to have your public key public, hence the name public key.

Linux Install

sudo apt install gnupg
or
sudo apt install gnupg2
or
yum install gnupg
or
yum install gnupg2

depending on your needs https://superuser.com/questions/655246/are-gnupg-1-and-gnupg-2-compatible-with-each-other/655250

Windows Install

Silent Install Switch:  gpg4win-x.y.z.exe /S
Silent Uninstall Switch (32-bit System) "%ProgramFiles%\Gpg4win\gpg4win-uninstall.exe" /S
Silent Uninstall Switch (64-bit System) "%ProgramFiles(x86)%\Gpg4win\gpg4win-uninstall.exe" /S
You may have to add 
C:\Program Files (x86)\GnuPG\bin
To your environment PATH so when you run gpg.exe it finds it automatically

Brief Usage 

gpg --list-secret-keys
gpg --list-keys
assuming with have a key with recipient jeremybusk@gmail.com
echo hello > hello.txt && gpg --output .\hello.txt.gpg --encrypt --recipient jeremybusk@gmail.com .\hello.txt && gpg --output newhello.txt --decrypt .\hello.txt.gpg

Interacting

There are many ways of interacting with pgp via libs or wrappers in code - https://pypi.org/project/python-gnupg/

Cheatsheet

There are many out there. This is a shameless rip, for now, off one.

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:
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 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.

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.
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 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
--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

More Considerations

Random Generators

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