<RC4SE.DLL v1.00>
128 bit RC4 (TM) Encryption 
Shell Extension and COM Automation
Server for Windows 95/98/NT4.
Freeware. Freely distributable.
Copyright (c) 1999, Gerard R Thomas.
email:<grt@wow.net><grt@geocities.com>
http://community.wow.net/grt/rc4se.html

This program is "freeware" and may be used and copied without
fee or obligation.
Run the installer for license information.

This software uses the MD5 (TM) (Message Digest 5) and RC4 (TM) 
(Rivest Cipher 4) algorithms of RSA Data Security Inc. as implemented
by the Microsoft Crypto API.

Installation:
The rc4se.zip file contains these files:

file_id.diz (package information)
readme.txt  (program information)
install.exe (program installer)
install.exe.sig (PGP signature)

Run the INSTALL.EXE file to install the program on your system.

Note: 
You must have administrative privileges to install and uninstall
this program on Windows NT.
 
Uninstall:
Use the Control Panel | Add/Remove Programs applet to uninstall
the program.

Operation (Shell Extension):
In Windows Explorer, right click on a file or a group of files
and select the "RC4 encrypt/decrypt" option.
Type a password into the dialog.

This will encrypt/decrypt the file or files using "strong" encryption
(RC4 stream cipher using a 128 bit session key derived from the
MD5 hashed salted password).

By default the "encrypt" and "decrypt" checkboxes are checked.
With this setting the extension automatically encrypts or decrypts
each file in the group selected based on the state of the file
(i.e. if encrypted, the file will be decrypted; if un-encrypted, it 
will be encrypted). The checkboxes allow more control over this
by enabling or disabling encryption or decryption operations for
the entire file group during the session (instead of simply toggling
the file state).
Checking the "compress" checkbox will cause the file to be compressed
prior to encryption. While this is slower, it is more secure.

Operation (COM Automation Server):
The interface consists of three methods:

EncryptFile(inputfile,password,compress)
DecryptFile(inputfile,password)
WipeFile(inputfile)

parameters:
inputfile is a string giving the filename (including full path)
compress is an integer that indicates whether the file should be compressed
prior to encryption. Valid values are 0 (no compression) and 1 (compression)
password is a string giving the conventional password

Example Usage:

(a) using the Windows Scripting Host and JScript

// EXAMPLE.JS
rc4obj = WScript.CreateObject("RC4AUTO");
rc4obj.EncryptFile("D:\\Reports\\JUL99.DOC","testing",0);
rc4obj.WipeFile("D:\\Reports\\SCRATCHPAD.XLS");
//end of file

(b) using Visual Basic

(1) choose Standard EXE project
(2) choose Project | References and check the "RC4 COM Interface"
    checkbox.
(3) place a commandbutton control on Form1
(4) enter the following code

Private Sub Command1_Click()
  Dim myRef As New RC4AUTO.CRC4AUTO
  myRef.EncryptFile "d:\reports\new.mdb", "testing", 0
  myRef.DecryptFile "d:\reports\Jul99.DOC", "secrets"
End Sub

(5) run the code and click on the button

Note:
This extension uses the Microsoft Crypto API functions of
Windows 2000/NT5, Windows NT 4.0, Windows 98 and 
Windows 95 OSR2. Older versions of Windows 95 are only
supported if Internet Explorer 3.0 or greater is installed.
MSIE 3.x or greater installs the needed Crypto API libraries
and updated version of the interface library ADVAPI32.DLL.

Note:
This extension requires that RSAENH.DLL (the Microsoft Enhanced
Cryptographic Service Provider) be installed. This provides 128 bit
cipher support. It is not sufficient for only RSABASE.DLL 
(the Microsoft Base Cryptographic Service Provider) to be present
since this will only provide 40 bit cipher support.
The 128 bit upgrade patches may be obtained from
ftp://ftp.replay.com/pub/replay/browsers/128bit/

Note:
This extension may be disabled at any time by typing into the
Start | Run

regsvr32 /U rc4se.dll

It may be re-enabled with the command

regsvr32 rc4se.dll

In the disabled (unregistered) state the extension will not be
loaded by the Explorer shell and its COM typelib interface 
will be unavailable for use.

Note:
It is not necessary to have MSIE 4.x or 5.x installed to use the
128 bit upgrade patch. Simply extract the files from the package
either using WinZip or manually by running the installer with the
/C /T switches
e.g.

nph-iefinal.exe /C /T:C:\TEMP

will extract the contents of the IE4 128 bit patch to the folder
C:\TEMP.
You then copy the enhanced CSP (RSAENH.DLL) and its signature
file (SIGRES.EXE or ENHSIG.DLL) to the \System folder (win95/98)
or \System32 folder (NT4) and register the file using

regsvr32 rsaenh.dll

This will register the CSP and provide "strong" 128 bit cipher
support for the Crypto API.

Note:
The PGP signature may be used to verify the integrity of the 
executable. The executable is signed with my PGP DSS key.
[4096/1024 bit DH/DSS <grt@wow.net> <grt@geocities.com> 
Key ID: 0xFF7155A2 Key fingerprint:
61DF 0468 0570 4615 8FF5  7530 5B3C 2165 FF71 55A2]

1999 06 13
Gerard R Thomas
Port of Spain
Trinidad and Tobago
