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Thread: Security and Demo in Visual Basic

  1. #1

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    I am trying to create a demo program in Visual Basic for distribution. I want the demo to stop working after a certain number of days. One way to implement that is by using the registry to keep track of when the program was installed. And whenever the program is executed, I can calculate the number of days. But the disadvantage is, I can change my system clock backwards and still use the demo. Any suggestions ?

    TIA!!

  2. #2
    Former Admin/Moderator MartinLiss's Avatar
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    Take a look at this chapter in a book by Dan Appleman

    ------------------
    Marty

  3. #3
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    create file *.dll and insert in the path

    C:\windows\system\ and registry the day of instalation and compare with date to bios at load form or run program is the time most then load the message.
    this dll create encrypt and the extension dll is lib but not registry the person I'm working in my demos program and is very dificult descifrate


    ------------------
    carlos alberto perez vergara
    carlosapv@hotmail.com
    analist programming
    visual basic 5.0


  4. #4
    Hyperactive Member Steve Stunning's Avatar
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    >One way to implement that is by using the registry to keep track of when the program was installed. And whenever the program is executed, I can calculate the number of days. But the disadvantage is, I can change my system clock backwards and still use the demo. Any suggestions ? TIA!!

    Sure.... Do this...

    Dim InstallDate as Date

    Text = GetSetting("MyPrograms",Title,"Install Date","")

    InstallDate = Text

    If InstallDate > Date then
    msgbox "Date set back!!"
    end if



  5. #5
    Hyperactive Member Juan Carlos Rey's Avatar
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    By far, the best way is a control named Active Lock.

    Get yours at: http://www.activelock.com

    ActiveLock will let you make Demos, Crippelware (not sure about spelling), Trials, Shareware, etc. with easy, and the best part: It's freeware.

    Deserves a look!

  6. #6
    Hyperactive Member Steve Stunning's Avatar
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    Active Lock is a very nice control you can add to your program and it is easy to use. I actually created my own and love it!!

    But I am not giving it away.

  7. #7
    Hyperactive Member Juan Carlos Rey's Avatar
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    Bob: that is what Active Lock does:
    1- You can disable some features and enable them when your user registers, by a Keycode you give him. That is what they call "CrippelWare" or so.
    2- Make a demo/trial based on either a number of days the program is used, or the times it is opened.
    3- If the user modifies the date in his PC, the program stops executing at all and gives a warning you can customize, like "date invalid, call 1-800-etc, mention error number 001-001"
    4- If the user tries to re-install the program, it will warn him: "your trial period has expired, please register" or whatever your message is.

    Give it a try!

    [This message has been edited by Juan Carlos Rey (edited 12-04-1999).]

  8. #8
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    What's to stop a person from reinstalling it each time the trial period is over? Rather than do the whole trial period, could you just disable some of the important features like save, or copy and paste? That's what Adobe does.

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