WINZIP Encryption - detect encrypt type

Posted on 2008-11-18
Last Modified: 2012-05-05
I'm looking for a way to determine which encryption method was actually used.  As far as I can tell, WINZIP has 3 options.  The "2.0"  method, the AES 128 bit method and the AES 256 method.

A programmatic solution would be ideal, maybe something involving .NET, but I'de settle for any way of detecting it on a zip file that is already created.

The only indicator of encryption that I see is a asterisk next to the filename in the winzip dialog.  I just don't know how to determine which encryption method was used.

The reason I want to know is because I don't want anything to be encryped with the "2.0" method.

The first solution that came to mind was to use infozip to try and decrypt the file and if that worked, then I know that "2.0" was used because infozip doesn't support AES encryption, but that method isn't really a good sollution for me.
Question by:Jeff Darling
    LVL 11

    Author Comment

    by:Jeff Darling
    I think I just found the answer, but I'll leave this question open to the experts for a while to see if they agree or have anything to add.

    LVL 13

    Accepted Solution

    Most likely you'll have to dig deep into the WinZip header formats.

    I personally haven't done this before (detecting the encryption type used). But this is where I would start, and I believe is the correct direction (although extremely tedious).

    The WiKi

    Hope that helps
    - Kelvin
    LVL 13

    Expert Comment

    I found this quite useful in explaining the encryption process and some of the header content.
    LVL 13

    Expert Comment

    >> I think I just found the answer, but I'll leave this question open to the experts for a while to see if they >> agree or have anything to add.

    Yep. Agreed : )
    LVL 11

    Author Closing Comment

    by:Jeff Darling
    thanks for the response.  

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    Featured Post

    How your wiki can always stay up-to-date

    Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
    - Increase transparency
    - Onboard new hires faster
    - Access from mobile/offline

    In this era, as you know, cybercrime and other sorts of frauds using the internet has increased day by day. We should protect our information assets and confidential information from getting exploiting by the attacker or intruders. Most of the fraud…
    Outsource Your Fax Infrastructure to the Cloud (And come out looking like an IT Hero!) Relative to the many demands on today’s IT teams, spending capital, time and resources to maintain physical fax servers and infrastructure is not a high priority.
    Sending a Secure fax is easy with eFax Corporate ( First, Just open a new email message.  In the To field, type your recipient's fax number You can even send a secure international fax — just include t…
    Internet Business Fax to Email Made Easy - With eFax Corporate (, you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, fr…

    779 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    14 Experts available now in Live!

    Get 1:1 Help Now