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Help
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1996-11-10
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Help for pgp !crypter
by
Mike Williams (MEWsoft)
Sept 22nd 1995
!Crypter is designed to simplify the task of decrypting, encrypting and
signing text files primarily for e-mail, using pgp (Pretty Good Privacy).
This application is useless by itself. To make use of it you need an Acorn
version of pgp. There is an excellent !pgp version (2.6.2i) by Gareth
McCaughan which is currently available on hensa, or in the mirror on Demon.
(There is an earlier version of pgp (2.3) which I do not recommend.)
!pgp is in pub/mirror/micros/arch/riscos/a/a304.
There is also a useful front end which simplifies the process of creating and
handling keys. It is !PGPwimp by Peter Gaunt and can be obtained from Demon
in the pub/archimedes directory.
Both of the above applications come with full documentation so I assume you
are reasonably familiar with the principles underlying pgp.
Installation:
============
!Crypter is best stored with !pgp because it needs to have seen !pgp so that
it knows where to find the keys and other files.
Running:
=======
Running !Crypter installs it on the Icon Bar and opens its main window.
1 To decrypt a document:
a The document to be decrypted can be either a file on disc, or you can
drag the save icon from a newsreader such as !TTFN onto the !Crypter
Window.
If the document is indeed encrypted then the decrypt icon on the window
should be automatically set and the document name inserted into the name
icon at the bottom.
Drag the text icon to a directory where you want the decrypted document
to go. If you keep the same name and drag the icon to the same directory
then the decrypted file will overwrite the encrypted file.
b The Task Window opens and pgp displays its messages. This part of the
proceedings is under the control of pgp and !Crypter is no longer
involved. Close the Task Window when decryption is complete.
2 To encrypt, or to encryt and sign a document:
a The document to be encrypted must exist as a text file on disc.Typically
you will have written an e-mail using !Edit or !Zap and now wish to
encrypt it prior to sending it.
b Drag the file onto the !Crypter Window.
Select Encrypt or Encrypt and Sign.
Select the User ID whose public key you have,and to whom you are going to
send the e-mail (the Target's ID). Either write the ID in the icon or
click on the selection button on the right. This uses a file inside the
Resources directory inside !Crypter which you can edit yourself.
(Choosing the Full List option on the name menu gives a full listing of
all of the public keys on your key ring. This list is created each time
the program runs. If however you add a key while the program is running
you will need to exit and restart the program if you wish to use that key
other than by manually entering the name yourself in the ID icon.)
Drag the text icon to a directory as described in 1.a above.
Proceed as in 1.b
3 To Sign a document without encrypting.
a As 2a above
b Drag the file onto the !Crypter Window.
Select Sign.
Drag the text icon to a directory as described in 1.b above.
Proceed as in 1.b
The name of the signed file ends with "/S"
NOTES
Viewing the output directly
If you wish to view the output from !Crypter without saving it, drag the
output icon onto a text editor such as !zap. It is best to drag it onto the
text editor icon on the icon bar. The text can then be read and/or saved
as required.
So a typical sequence might be:
Encounter a PGP encoded e-mail while using !TTFN.
Save the file (with or without header) directly into !Crypter.
Drag the !Crypter output onto the !zap icon on the icon bar.
After pgp does its work the decoded file should appear in a text window.
NB: This process produces some Scrap files inside !Crypter which are deleted
when !Crypter is exited. If your mail was confidential then you should make
sure that you do not leave the machine with !Crypter still running.
IDEA only encryption
This option allows you to encrypt a file into a very compact binary file
using a pass word or pass phrase and not using your keys. It is a usefull
option if you want to store sensitive information on disc (as long as you
remember the pass phrase). It is not part of the public key system and is
not designed for sending e-mail puroposes.
Verbose Messages
pgp (until a more Acorn orientated version is produced) opens a task window
and outputs messages describing its progress. If you have the Verbose
Message option selected then the messages are indeed a bit wordy. By
deselecting Verbose you cut the messages down to the essentials.
Automatic Password
You can avoid the tedium of entering your password every time by editing the
!Run file inside !Crypter.
The line: |SET PGPPASS "password" should be amended.
So if your password is "Bambi Lives" then the line should read
SET PGPPASS "Bambi Lives"
This obviously compromises your security if other people have access to your
computer. Ways of getting around this are described in the pgp documentation
along with pgp.
My thanks to Bob Bayford and to Gareth J. McCaughan for beta-testing and
useful suggestions.
Mike Williams (mike@mediajpn.demon.co.uk)
Public Key available from pgp-public-keys@pgp.ox.ac.uk