PGP Public Key Details

For contact details, see here.

pub   2048R/09A80C9A 2016-04-08
      Key fingerprint = EB86 DFC4 C60F 5A46 2302  8777 0E26 C8C9 09A8 0C9A
uid                  A.C. Norman <ACN.Norman@radley.org.uk>
sub   2048R/9C7EE0EF 2016-04-08

For use with ACN.Norman@radley.org.uk. This address is only used for communication with regard to this website or my teaching activities at Radley College, and for any other e-mail addresses of mine, another key should be used. Its fingerprint is at the bottom of this page.

Don't worry: you don't have to read this. You can cut-and-paste it or obtain it in a plaintext file.

Fingerprint:	EB86DFC4C60F5A46230287770E26C8C909A80C9A
Long Key ID:	0E26C8C909A80C9A
Short Key ID:	09A80C9A

Did you notice that the long and short key IDs are just the last 16 or 8 digits of its fingerprint respectively? It's obvious when displayed this way. See this document for more.)

A few words of explanation

A PGP key is used to encipher messages, usually ones in electronic form. You can use my PGP public key to securely communicate with me by e-mail, for example. A PGP key comprises a public key and a private key. My public key is available on this page, and is needed to encipher any message to me. Only I have access to my private key, however, and so any message enciphered using my public key can be read only by me. If the original copy is destroyed, even its author will not be able to restore it to plain text.

Anyone who wishes to protect their correspondence to me with encryption needs a copy of my public key. To reply securely, I will need a copy of their public key, since if I encipher the message using my private key, anyone who has seen my public key will be able to read it. This can be useful, however: since only I have access to my private key, I can prove that a message is written by me by enciphering it with my private key. Although anyone can read it by deciphering the message with my public key, they can be reasonably confident by doing so that the message came from me (or at least from someone with access to my private key).

It is essential, therefore, to guard access to one's private key. It is also important to make sure that you have a genuine copy of the public key of anyone with whom you wish to communicate. The only truly secure way to obtain a PGP public key is direct in person from its owner or via a trusted emissary. Any other source, where there is a risk that a key could be modified or subsituted by a sinister third party, must be treated with caution. Fortunately, there are a number of ways to safeguard the integrity of keys obtained from untrustworthy sources, such as the internet.

All PGP keys have a unique fingerprint, normally printed as a 40 character hexadecimal string. The PGP public key fingerprint, obtained through a tamper-proof medium (fax, telephone conversation, publication in a book or journal &c.), can be used to verify the validity of a key. A printed personally signed copy of my PGP public key fingerprints can be obtained direct from me by post, for which I ask a nominal fee of one pound sterling.

Keys can also be signed by other users of PGP, to show that those users are satisfied that the key is genuine. If I hand you a copy of my key in person, you could sign it and send it on to a friend who has a true copy of your public key. They will be able to get my key by deciphering it with your public key, and will know that since you have signed it, you have guaranteed its authenticity. Provided that he trusts your word, and knows that your key is genuine, there is now no need for him to meet up with me himself to get a good copy of my public key, and he will be able to encipher messages to me with it. In this way, I can satisfy myself that public keys really belong to the people who I wish to get in touch with despite not ever having met them by establishing a chain of trusted keys from my own key to their keys.

A good way to get your key signed is to participate in a key-signing party. Each participant at such an event bring along slips of paper with their public key fingerprint printed on it, and a form of photo ID, such as their passport. This enables the other participants to establish their identity, and they can then exchange public keys for signing after the event by e-mail (this will allow their e-mail address to be verified). Each person signs all of the keys of the people whom they met at the keysigning party, having checked their ID, public-key fingerprint and e-mail address.

My other public key

As I wrote at the top of this page, the key here is only really used with my Radley College e-mail address, which is a contact point for this website. I have another key for use with my other e-mail accounts, which is not available on the internet (yet), so as not to generate spam. If you need my other public key, e-mail me on the above address, and I'll send you my other key. Here are its details (though with the uids omitted):

pub   2048R/DA9D2F47 2016-04-08
      Key fingerprint = E6D1 8ABB 3408 D0E4 3032  AF5D B7F9 BE7A DA9D 2F47