Adding More Identification to GPG

In order to help the gpg key identify a specific person, it can include more information than the name, e-mail address and comment. It can include more e-mail addresses (who has a single e-mail address these days?) and a photograph. These extra identifiers are added to the key and signed by everyone exactly like the original identifier. Each identifier is called a uid.

Stimpy has a recent photograph available named photo.jpg. Since he has an ECN e-mail address, he also has a Purdue e-mail address, stimpy@purdue.edu. Plus Stimpy still works for his old company, Crocostimpy Industries. In order to have his gpg key include these extra uid identifiers, he will need to edit his key and make the additions. Each uid must be signed by his private key to certify that he put these extra uid identifiers into his key.

Note: photographs must be in a JPG format and should be as small (in byte size) as possible. A reasonable rule is to make a picture that is no larger than 240 pixels wide by 288 pixels high, and a size less than 10,000 bytes. Use a face shot like you would with a passport photograph.

$ gpg --edit-key stimpy@ecn.purdue.edu
gpg (GnuPG) 1.4.5; Copyright (C) 2006 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

Secret key is available.

pub  1024D/2BDE6D4E  created: 2007-03-01  expires: never       usage: SC  
                     trust: ultimate      validity: ultimate
sub  4096g/C0040CFC  created: 2007-03-01  expires: never       usage: E   
[ultimate] (1). Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>

Command> addphoto
                 
Pick an image to use for your photo ID.  The image must be a JPEG file.
Remember that the image is stored within your public key.  If you use a
very large picture, your key will become very large as well!
Keeping the image close to 240x288 is a good size to use.

Enter JPEG filename for photo ID: photo.jpg
This JPEG is really large (11298 bytes) !
Are you sure you want to use it? (y/N) Y
(at this point, the photo might pop up on the display...)
is this photo correct (y/N/q)? Y
                                
You need a passphrase to unlock the secret key for
user: "Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>"
1024-bit DSA key, ID 2BDE6D4E, created 2007-03-01

Enter passphrase: history eraser button
pub  1024D/2BDE6D4E  created: 2007-03-01  expires: never       usage: SC  
                     trust: ultimate      validity: ultimate
sub  4096g/C0040CFC  created: 2007-03-01  expires: never       usage: E   
[ultimate] (1). Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>
[ unknown] (2)  [jpeg image of size 11298]

Command> adduid
Real name: Stimpson J. Cat
Email address: stimpy@purdue.edu
Comment: Happy Happy, Joy Joy
You selected this USER-ID:
    "Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@purdue.edu>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
                                                     
You need a passphrase to unlock the secret key for
user: "Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>"
1024-bit DSA key, ID 2BDE6D4E, created 2007-03-01

Enter passphrase: history eraser button
pub  1024D/2BDE6D4E  created: 2007-03-01  expires: never       usage: SC  
                     trust: ultimate      validity: ultimate
sub  4096g/C0040CFC  created: 2007-03-01  expires: never       usage: E   
[ultimate] (1)  Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>
[ unknown] (2)  [jpeg image of size 11298]
[ unknown] (3). Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@purdue.edu>

Command> adduid
Real name: Stimpy the Cat
Email address: stimpy@crocostimpy.ind
Comment: Bus Driver
You selected this USER-ID:
    "Stimpy the Cat (Bus Driver) <stimpy@crocostimpy.ind>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
                                                     
You need a passphrase to unlock the secret key for
user: "Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>"
1024-bit DSA key, ID 2BDE6D4E, created 2007-03-01

Enter passphrase: history eraser button
pub  1024D/2BDE6D4E  created: 2007-03-01  expires: never       usage: SC  
                     trust: ultimate      validity: ultimate
sub  4096g/C0040CFC  created: 2007-03-01  expires: never       usage: E   
[ultimate] (1)  Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>
[ unknown] (2)  [jpeg image of size 11298]
[ unknown] (3)  Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@purdue.edu>
[ unknown] (4). Stimpy the Cat (Bus Driver) <stimpy@crocostimpy.ind>

Command> save
$ 

At this point, Stimpy now has a key with multiple e-mail addresses and a photo associated with it. Because of the extra e-mail addresses, the key can now be referred to by the Purdue mail address.

$ gpg --edit-key stimpy@purdue.edu
gpg (GnuPG) 1.4.5; Copyright (C) 2006 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

Secret key is available.

pub  1024D/2BDE6D4E  created: 2007-03-01  expires: never       usage: SC  
                     trust: ultimate      validity: ultimate
sub  2048g/C0040CFC  created: 2007-03-01  expires: never       usage: E   
[ultimate] (1). Stimpy the Cat (Bus Driver) <stimpy@crocostimpy.ind>
[ultimate] (2)  Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@ecn.purdue.edu>
[ultimate] (3)  [jpeg image of size 11298]
[ultimate] (4)  Stimpson J. Cat (Happy Happy, Joy Joy) <stimpy@purdue.edu>

Command> quit
$