Generating a GPG key for git tagging

First you need check if there is a gpg key for your ID.

$ gpg --list-key

If you have should appear something like this:

1. pub 2048R/6AB3587A 2013-05-23
2. uid xxx (gpg for xxx)
3. sub 2048R/64CB327A 2013-05-23

If there is no gpg key. You should create

$ gpg --gen-key

Next you have this output:

gpg (GnuPG) 2.0.14; Copyright (C) 2009 Free Software Foundation, Inc. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

Please select what kind of key you want:

1. (1) RSA and RSA (default)
2. (2) DSA and Elgamal
3. (3) DSA (sign only)
4. (4) RSA (sign only)

Your selection? RSA keys may be between 1024 and 4096 bits long. What keysize do you want? (2048)
Requested keysize is 2048 bits
Please specify how long the key should be valid.

         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years

Key is valid for? (0)
Key does not expire at all
Is this correct? (y/N) y

GnuPG needs to construct a user ID to identify your key.

Real name: xxx
Email address: [email protected]
Comment: gpg for xxx

You selected this USER-ID:
    "xxx(gpg for xxx) <[email protected]>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
You need a Passphrase to protect your secret key.

can't connect to `/xxx/.gnupg/S.gpg-agent': No such file or directory
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.

If you have a key already generated, you can tell git to use that specific key without worrying about matching between your git user ID (name+email) and the GPG key's ID. You should have your git user.email match one of the emails on your GPG key for your signed tags or commits to be useful to other users, though.

To set the key for global use on your computer, set your git global config with:

git config --global user.signingkey 6AB3587A

Or, you can set the user.signingkey for only the current repository you're in with:

git config user.signingkey 6AB3587A

The committer name is located in your ~/.gitconfig file. Change that entry to a real name (which is how you want to be committing, anyway). You can edit the file in your favorite editor, or just issue:

git config --global user.name "<name>"