Crypt.device V1.8 Copyright © 1992 by Timo Rossi <trossi@jyu.fi> and 
Risto Paasivirta <paasivir@jyu.fi>, all rights reserved.

This software can be freely used for non-commercial purposes.
We don't quarantee this works. Next release may be incompatible with
this version. For serious use you should read and understand the source
and compile it yourself. Please send us feedback and bug reports.

Crypt.device is ment to be used with harddisks to create small encrypted
file systems for 'critical data'. Like love letters, private rsa keys
and whatever data you don't think other people should be able to read.

Encrypting algorithm used is IDEA cipher in cipher block chaining mode. 
Each 512-byte device block is encrypted with block offset used as initial 
vector. See end of this file for IDEA patent info.


This distribution contains files:

README			this file
mountlist.crd		example mountlist entry
crypt.device		device

Makefile		makefile for crypt.device
cryptdev.a		device source code (from fdev)
idea68k.a		encryption source code

createfile		utility to create data storage file for device
createfile.c		source
resetdev		utility to reset/remove pass phrase from memory
resetdev.c		source


Installation:

Copy crypt.device to devs:
Copy mountlist.crd to devs: (or append it to your mountlist file)
Create the storage file for encrypted data using command:
>createfile crd0filename 1760
For floppy-sized encrypted unit, blocks = Surfaces * BlocksPerTrack *
Cylinders = 11 * 2 * 80 = 1760, if different size is needed modify
mountlist as needed.

Set assign so cryptdev can find the file and mount device unit:
>assign crdev0: crd0filename
>mount CRD0: from mountlist.crd
You might include these commands to your user-startup file.

When CRD0 are first accessed, crypt.device prompts you to type
and verify pass phrase. There is no validity checking, if you give
wrong/new pass phrase, unit behaves like unformatted partition.
You need to format filesystem before use. Command:
>format drive CRD0: name Whatever

Pass phrase should be at least 10 characters long and nothing that
can be easily quessed. Use different pass phrase for each unit.
Now CRD0: can be used like any small disk unit.

If you gave wrong pass phrase or need remove pass phrase form some unit 
without turning computer off, command resetdev unit [device.name]
will do that. Try:
>resetdev 0

Be aware that file system buffers may still be in memory decrypted. Use
power switch if in doubt. Resetdev can be used to reset devices other
than crypt.device, but we don't know if that's useful for anything...

You can add more units by creating more mountlist entries and storage
files. Each unit has it's own pass phrase and it's recommended to use
different for each one.


PATENT
IDEA is registered as the international patent  WO  91/18459
"Device for Converting a Digital Block and the Use thereof".
For commercial use of IDEA, one should contact

ASCOM TECH AG
Freiburgstrasse 370
CH-3018 Bern, Switzerland