The how-to guide to PGPing on your very own Acorn

By PowerHouse

AKA Aidan Gustard

Introduction

PGP stands for Pretty Good Privacy. It is probably to best type of encryption available for computers anywhere around the world. It allows you to encode your E-Mails, Newsgroups etc into a mess of seemingly random ASCII chracters and back again (if you have the key for it).

How does it work?

If we take a system like the Enygma back in the 40's. It encoded it's messages using 1 algorythm at both ends. It was a very succesful coding system untill it was cracked. Why was it cracked? Because it used only 1 key. PGP is a world apart. It is a very simple system really. It uses 1 key to encode the message and another do decode it. But here is the beaty of it. Everyone in the world can have the encodeing key, but they will never be able to decode any message made for you, even though the key that made it because the only one that will convert the binary back into the original ASCII is the one that you keep. The Secret key! You may think that "If it can encode it, it can decode it!" but you will be wrong. Why? Because when it encodes the message it is using complex algorithms that only the secret key can decode. You can encode any file type with pgp. You can not pgp directories, but Archives are permitted. So pictures, text files, Impression files, you name it can be coded and sent accross the net. Enough of the theory. Lets get it set up!

Setting up PGP

If you do not already have PGP, you can download it from this site or a choice from the others listed at the end of this page.

The first thing you need to do is place the pgp executable within your library Directory if you have one or within !PGPWimp it's self. If you do not place the app file in PGPWimp then you must specify the path within the !Run file found inside !PGPWimp like so:-

Set pgp$path {?????}

Making your Secret key

There are 2 ways of making the keys. The professional way or the User way. Let us do it the user way.

Run the !PGPwimp application. When the window comes up, press the menu button on the mouse. Go to Edit then select Make key. A task window will come up with a prompt giving 3 options. This is the number of bytes that the key will be made out of. Remember, then more bytes the key is made out of, the securer your data will be! Now there are 3 options to choose from. The last is 1024 bytes long. This means that the key is very, very secure! However, it will also take longer to create. (about 10 mins on a 25mhz A5000) but is well worth having.

You will be asked to enter your personnel ID. I reccomend you use your known nick and Email address. You can if you want use any identification you want but to keep confusion at bay, keep it simple. Too many Identnties can be very bad.

Now you will be asked to enter a pass phrase. The phrase must be long enough to cover the 30 charachter requirement but not so long that it will take you hours to type in. What I did was I went through my notes from college and typed in an extract. You could do the same if you want, just don't pick something so obvious that everyone will be able to get if they know you! You will have to wait a bit while the key is created. You will see a line of chars creep accross the screen. You will know that the key is finnished as the curser will drop to the line below......and do nothing. Look inside the !Pgp application and if you did the above correctly, there should be 3 new files there:

pubrng/bak
secrng/pgp
randsd/bin

Creating the Public key

It is now time to create public keys so that you can send them out. Click the menu botton over the !PGPwimp window, slide your rodent over to extract and a window should open up. Enter your identification, the file name then drag the icon into your desired directory. After a little wait, you will have your public key which you send to people you want to PGP with. You can also extract other keys. There are reasons for this I will touch on later.

Corresponding with people using PGP

Once you have a few public keys from people who have set it up, you will want to send your messages PGPed. For this you must have the public keys of others. Run !PGPwimp and drag the file you want to code into the window. Make sure that the Action window says Encrypt. Enter the ID of the person you want to send the file to. Drag the icon to a directory and away it goes. You will have a PGPed message. NOTE: you will not be able to decode this file as you do not have the Secret key of the person you are sending it to. That is the Joy of PGP.

Decoding your replies

You have sent out your first tentative messages and have recieved a replie that has been PGPed. Run !PGPWimp, drag in the coded file, select Decrypt in the action window by clicking the left mouse button on the arrow (Note: Not the menu and drag the output Icon into a Directory. A task window will pop up and prompt you to enter your pass phrase. If you typed it out correctly, then it should start to decode the message. If you are saving the decoded file by the same name as the encoded one, press Y to continue. If not then ignore what I just typed :-). You can now read the file and see what it is.

Adding keys to your key ring

When you receive a key, you will want to add it to your key ring so that you can replie to them with PGPed files. This is how you do it. Run !PGPwimp. Select Decrypt in the Action window. Drag the file containing the ASCII key into the window and click OK. A task window will appear so just follow the prompts.

As far as I know, there are three places that you can get the !pgp applications from. These are:

• The PGP application
• The PGP Front end
• Pgp module Version 1.62i 95k
• My key (Remember to change the /txt serfix to /asc after downloading)

GWood for helping me set up my own version of !Pgp

And thanks to the following for writing/porting Pgp onto the acorn

Phillip Zimmermann who wrote pgp
Gareth McCaughan who ported Pgp onto the Acorn
Peter Gaunt who wrote Pgpwimp, the GUI