PRODUCT  :  Paradox Engine                        NUMBER  :  1375
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  1/2

    TITLE  :  Table Passwords and the Paradox Engine




  The Paradox Engine DLL for Windows,  versions 2.0 and 3.0, treat
  passwords differently than the DOS version of the Paradox Engine.
  When one application adds a password to the password table, every
  application running at that time will be able to use that
  password when opening a table.

  Let us go in to a discussion of how passwords work with the DOS
  version. It is possible to Encrypt a table with PXTblEncrypt.
  When this is done, the data is not readable unless you enter a
  password with PXPswAdd. This password allows you to open any
  normal table, and any table that was encrypted with that
  password. The passwords are maintained in a list. You can remove
  a password from the list by calling PXPswDel.

  Under Windows, while the password that you added with PXPswAdd is
  in the table of valid passwords, any other application in Windows
  that uses the Paradox Engine DLL will be able to use that
  password when opening a table. This password remains active for
  ALL instances until PXPswDel is called to remove it from the
  table. This _IS_ by design. The feeling is that since there is
  only one keyboard, there was no reason to provide security at the
  task level. The solution to limit a password to one application
  is the following sequence of calls (in order):

                PXPswAdd()
                PXTblOpen()
                PXPswDel()

  This will have the password in the global table for a very brief
  time and should fix the problem of multiple instances.

  This whole discussion leads to other issues. What if two
  different applications add the same password with PXPswAdd to the
  DLL? It gets added to the table twice. Then, each task will call
  PXPswDel and remove it from the table.

  Since passwords can be in the table more than one time, the table
  needs to be larger. This has been resolved, the table can now
  hold up to 50 passwords for the DLL. Please remember, Object
  Vision is based on the Paradox Engine. Anybody using Object
  Vision and writing a Paradox Engine  application will be using
  the same DLL ( make certain to use the later DLL ).














  PRODUCT  :  Paradox Engine                        NUMBER  :  1375
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  2/2

    TITLE  :  Table Passwords and the Paradox Engine




  DISCLAIMER: You have the right to use this technical information
  subject to the terms of the No-Nonsense License Statement that
  you received with the Borland product to which this information
  pertains.