(increase to 500 pts if solved in 30min) Wireles WEP key mismatch problem

Posted on 2005-04-12
Last Modified: 2008-02-01
I am trying to get my laptop working with my access point

it works without web

and i generated 4 WEP 128 Bit HEX keys for ages ago

i fill out these in my access point, and i stored them on my harddrive


I can fill them all out in my access point(Conceptronic C54APT)
and i have to select a VALID key which i used to select the FIRST key

then on my laptop
i have a WPC54G Linksys PCMCIA Card.
i filled out the WEB 128 bit HEX TX Key (where i can only select one key instead of 4)
and i used to fill in KEY2 here

so as far as i understand KEY1 vs KEY2, this worked for me for a long time, until my laptop hd crashed, and now i restart it, and i cannot get it working anymore

so could anyone Explain my WHY i have to define 4 keys on the AP and only 1 on the Laptop

And could anyone define why i have to define a KEY number on the laptop as well as on the AP between 1 and 4

Solving my issue within 30 minutes will increase points to 500 pts

Question by:danny_ebbers
    LVL 13

    Accepted Solution

    In most cases the sending station will use a different IV for each frame (this is not required by the 802.11 standard). When transmitting messages having a common beginning, such as the "FROM" address in an e-mail, the beginning of each encrypted payload will be equivalent when using the same key. After encrypting the data, the beginnings of these frames would be the same, offering a pattern that can aid hackers in cracking the encryption algorithm. Since the IV is different for most frames, WEP guards against this type of attack. The frequent changing of IVs also improves the ability of WEP to safeguard against someone compromising the data. In other words, the use of 4 wep keys makes it harder for a hacker to locate and break a single key.
    LVL 4

    Author Comment

    yes but how should it correspond

    which key should i define in my laptop
    and which one should be the valid one on my AP
    to get a working encryption
    LVL 1

    Assisted Solution

    It has been my understanding that you should only fill out one key in the ap and leave the other three blank.  You may fill out all four, but this just makes it simple to change the key say once a week on the ap.  Does the ap's web interface allow you to choose which of the 4 keys is active?

    If Key1 is active you should be using Key1 on your laptop's pcmcia card.  Make sure you copy and paste or double check for typos.

    I know some wireless encryption standards can use a list of keys and key management which it rotates to enhance security, but I don't think that wep can do that.  I believe that ability would be part of the WPA protocol.

    Here is a link for reference on encryption standards:
    LVL 79

    Assisted Solution

    You only 'have' to define one key. Select Key1 as the valid key, "shared" mode
    On the client, use the same key as key1.
    When you have 4 keys on the AP, then any of the 4 keys should work on the client.
    LVL 13

    Expert Comment

    Any one of them will work, once the laptop authenticates a key will be chosen at random for each packet making it hard for the a hacker to break.  Any key will work, but after that the key is distributed at random after negotiatied with the client and host.
    LVL 4

    Author Comment

    Oke i am starting to understand it now.
    and i have connection to the access point right now..

    i only experience problems using the DHCP: i will post this in a new question with new points.. i will paste a link in in here in a moment.
    LVL 4

    Author Comment

    LVL 10

    Expert Comment

    the idea of having multiple keys on the ap is that you may assign different keys to different usergroups. suppose you dont want to have a certain group on the ap anymore you simply delete that key and you dont need to reconfigure your other clients anymore.

    as for your non-working key: the encryption of "human" keys (words a human can remember) to the real key (128bit, resp. 16 hex-characters) are not really standart (and may even change inside one manufacturer... I remember I once had a Zyxel AP with ZyAir-Card that did not do the same Key-Conversion). so if you take

    "KEY1XXXXXXX" as your human remindable key and you put it on both, your AP and your card, then the hex keys may not match. Most often afer entering the "HUMAN" key you can see what it was converted to... so be sure the to HEX-Values are exactly the same.
    LVL 4

    Author Comment


    I'll split points:

    100 to arosboro
    100 to lrmoore
    300 to eatmeimadanish (First,fastest,valid replyer)

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