
Advanced ARJ Password Recovery 1.02 (c) Elcom Ltd., 1998
========================================================
Note: this is the pre-release version of the program.


Contents
--------

  Description
  Requirements
  Usage
  Known bugs and limitations
  Future enhancements
  Registration
  Technical support
  Where to get the latest version


Description
-----------

This program (Advanced ARJ Password Recovery, or simply AAPR)
can be used to recover your lost password for ARJ archive. At
the moment, there is no known method to extract the password
from the compressed file; so, the only available method is
simple "brute force" attack.

Well, there are a lot of programs like this around, but
all of them have their own "pros" and "cons". Here is a brief
list of AAPR advantages:

- The program is smart enough to avoid giving you "false"
  matches, as many others do. If it says that the password is
  here, then it really is.
- The program is customizable: you can set the password length
  (or length range) and the character set to be used to generate
  the passwords.
- The program is very fast: up to 30 million passwords per
  minute (on Pentium-200/MMX).
- The maximum password length is not limited.
- No special virtual memory requirements.

The next versions will have much more useful features, of
course.


Requirements
------------

- Windows 95 (any version), or Windows 98, or Windows NT 4.0 running
  on Pentium CPU
- 8 megabytes RAM
- less than 600 kilobytes of hard disk space
- patience...


Usage
-----

The program is a windows application and have powerful
graphical user interface (GUI). You can run this program
from "Advanced ARJ Password Recovery" group created by
the installation program.

You have to select the following:

- Name of the file. Use the "Browse" button to pick it from
  the list.

- Password length: maximum and minimum.

- Password range options (what characters have been used in
  the password), if you have this information. You can choose
  from all caps, all small letters, all digits, all special
  symbols; or just all printable (includes all of the above).
  In version 1.02 you also can define your own charset. Just
  click a checkbox "Custom charset" and "Define" button. In
  appeared dialog box enter all chars of your password range.
  For example: if you remember that your password was entered
  in the bottom keyboard row ("zxcv...") - your password range
  will be "zxcvbnm,./" or in caps: "ZXCVBNM<>?". You can also
  define both of this options: "zxcvbnm,./ZXCVBNM<>?".
  
- Analysing option -- block size analysing and Huffman table 
  analysing. The block size analysing is for advanced users and
  turns on analysing the block length (in archive). The value
  given in this option is a "percentage". It allows to set the
  block length. If it is used, the program performance could be
  much better, but there is a chance that the password will not
  be find at all. The optimum value is 30%; actually, it depends
  on file contents, i.e. distribution of "redundant" segments in
  the compressed file. The Huffman table analysing must be always
  turned "on". It improves analysing speed up to 50%. With this
  option, the program analyses some  Huffman table parameters,
  idential in all ARJ-archives.

- Priority -- normal or high. If you want to start AAPR as
  "background" process, you must select "Normal". If you want to
  increase the performance of AZPR, select "High", but please
  note that this will decrease the performance of all other
  applications running on your computer.

When (if) the password is found, the program prints it (as well
as the number of passwords which have been tested, and the
program speed):

'qwert' is a valid password for this file
Processed 1760765 passwords
time = 22 second(s)
speed = 80034 passwords/second

If all possible passwords (in the given range) have been verified
without success (so the valid one has not been found), the
message is:

Password not found in specified range
Processed 456976 passwords
time = 1 second(s)
speed = 456976 passwords/second


Known bugs and limitations
--------------------------

- The length of first encrypted file in archive should not
  exceed 8 megabytes.
- The program might not work with archives created with ARJ
  newer than version 2.60.
- When files in archive are "stored" (ARJ method 0) of packed
  with method 4 - performance reduces significantly because it
  requires to unpack all file.

Future enhancements
-------------------

As we already noted, this version is actually a "pre-release".
We know that it can be improved, and here are some facilities
we're going to implement:

- Ability to select totally custom character set, probably
  using regular expressions.
- Unlimited file size.
- Selecting particular file to crack.
- Automatic (smart) selection of the file to crack, according
  to size, password complexity etc.
- Running as a service under Windows NT.
- Dictionary-based attack.
- "Known plaintext" attack.
- Ability to interrupt the program at any time, and resuming
  it later (from the same point).
- Working on SMP systems (when more than one CPU is available).
- Further performance optimizations.

If you have any ideas how the program can be improved, please
don't hesitate to contact us! Your comments are very appreciated.


Registration
------------

This program is distributed as shareware (look at "license.txt"
for details). Being unregistered, it does not allow to set the
maximum password length.

After you register (look at "order.txt" for details), we'll
send you your personal registration code. You'll just have to
click the "Register" button; the program will open the input
window to enter the registration code; after you do so (you can
use cut'n'paste to avoid typing errors), it will have full
functionality.

Please note that your registration will be valid for all future
versions of AAPR.


Technical support
-----------------

For technical support, please contact us at support@elcomsoft.com.
In the subject of your mail, please write "AAPR x.y" (where x.y
is the version number), followed by "problem", "suggestion" or
whatever.


Where to get the latest version
-------------------------------

The latest version of AAPR is always available from our
web page at http://www.elcomsoft.com/aapr.html.
