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1993-07-05
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-============================================================-
-=+ EN v1.0c - A cheap file encrypter - (C)1993 Richard T. Bruce +=-
-============================================================-
EN is a shareware file encrypter/decrypter with a strong encryption routine
that is most complex and hard to defeat. If you use this software and forget
or mislay your password/key code then I nor anyone else can help you recover
your work.
EN is very simple in operation and requires only input for three questions.
The first is the input filename, that is the file that you wish to be
encrypted or decrypted. The second is the filename for the output of target
file. Note that if you specify the same input and output you will overwrite
the original file. The third and final input is the key code or password.
This can be between 1 and 79 characters long, we recommend a password of 6
or more chars for optimum security. You may find EN very slow, yes speed is
not ENs strong point but, as you will no doubt find out, EN makes up for its
weaknesses with its high performace in encryption terms.
NOTES :
EN requires a password, the password can be from 1 to 79 chars long.
EN outputs a dot (.) after processing 256 bytes.
EN is v1.0 so there are probably a FEW bugs lurking, if you do come across
any bugs please let me know.
EN is written in entirly in optimised 8086 assembler and is very compact
(under 1k) in size and is faster than programs written in higher level
languages like C or Pascal.
EN uses normal DOS calls and should not conflict with any other hardware or
software. One notable exception is usage of interuppt 29h which outputs a
character. This is used for producing the dot, all versions of DOS above 3
will support this and I dont see Microsoft changing this in the forseable
future.
EN's source code is 261 lines long and is 11,477 bytes long.
EN has built in protection from casual hacking and viewing. EN uses an
encryption routine on itself and then checksums itself to check for tampering.
Although not foolproof it does stop the odd person sticking their name inside.
Tests
~~~~~
EN has been tested along side other shareware file encrypters.
ARC, PKZip, Arj, Lock It & HyperDES.
The slowest was HyperDES, EN was second slowest. Lock It is nearly as good
as EN but not quite. Arj and ARC were both terrible and can easily be
cracked. PKZip was the best in speed and encryption.
Using SMARTDRIVE v4.1 EN processes 1,785.7 bytes per second on small files.
Without SMARTDRIVE EN processes 1,597.4 bytes per second.
On a 500,000 byte file EN took 4 minutes and 33 seconds or 273.53 seconds
making it 1,827 bytes per second on average.
Tests conducted on a 386SX-25 with 40mb IBM, IDE 13ms hard disk with 14mb
free, fully optimised using SPEED-DISK and running with DOS 5 and SMARTDRV
4.1.
Problems
~~~~~~~~
"EN reports a failed CRC check, what does this mean ?" -
EN performs a self check in memory, this means that if a virus attacks EN it
should be detected. Since the check is in memory you can still compress EN
with PKLITE.
History Report
~~~~~~~~~~~~~~
26-06-1993 - 1.0a - Started work on EN
04-07-1993 - 1.0b - Now EN supports files of more than 64k !
05-07-1993 - 1.0c - Oops! would only take an 11 char filename, now 12 !
SUPP0RT SHAREWARE
=================
If you find EN useful and wish to receive the latest version customised with
your name then please send me a cheque or P.O for £5 (along with your name and
type of PC) and I'll send you a customised version of EN (the latest version)
along with around 30 other programs written by myself.
Richard T. Bruce
70 Craigpark
Dennistoun
Glasgow
G31 2NN