Using GPG to Encrypt Messages

You might have been using GPG for years.
Do you often send encrypted messages to your friends?
Or maybe you don't even know your friend has a pub key.

If you are new.
There are high-quality documents written by GitHub. Start with this one for example: Generating a new GPG key

Sharing public keys with each other

Using key servers

Find a key on key servers

gpg --search-keys "HackingGate"

List keys

List GPG keys associated with i@hackinggate.com

gpg --list-keys i@hackinggate.com

Upload a key to a key server

If you want your key available on the key server. Just upload it.

gpg --send-key 85E38F69046B44C1EC9FB07B76D78F0500D026C4

But wait. Not everyone's pub key is available on key servers. You can't make sure keys on key servers are 100% real.
Someone could claim themselves as yourself.
What to do?

Keybase.io

Keybase.io came to solve that. They will use additional information such as a tweet, a DNS record, a gist to make sure you are yourself. But still, not everyone is using it. And I don't personally like Keybase.io. Because the setup process will upload your private key by default. It's NOT safe.

GitHub could be the best solution

Almost every developer has a GitHub account. And lots of them using GPG sign their git commits.

URL for GPG pub key

https://github.com/<username>.gpg

Example

Import a GPG pub key from GitHub user HackingGate (which is me)

curl https://github.com/HackingGate.gpg | gpg --import

Encrypt messages

gpg --encrypt --sign --armor --recipient email@example.com message.txt

Send the file (or copy text from) message.txt.asc to the owner of email@example.com.
Only she/he can decrypt the encrypted message.

Decrypt messages

gpg message.txt.asc