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A5/1 to A5/2 ciphering algorithm

Viewing 15 posts - 1 through 15 (of 19 total)
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  • #57712 Reply
    bonoatana
    Guest

    hi all,
    at radio level , what could be the consequences to move from A5/1 to A5/2 ciphering algorithm. the cange is need to be made on Ericsson BSC R8A release , is the reboot of the site is mandatory for example…

    #57713 Reply
    Pan
    Guest

    Dear, bonoatana! I don’t know what should you do with Ericsson BSC, but A5/2 algorithm is not supported by some MSs (e.g. Nokia N73, some Sony Eric and others).

    #57714 Reply
    Pix
    Guest

    Bonoatana,

    A5/2 is a weak algorithm, it is recommended to NOT use it (recommended by GSM World Association)

    Keep your A5/1, it is stronger, more secure.

    Soon, you’ll use the A5/3 which is even stronger.

    To answer your question : I don’t know, sorry.

    Cheers,
    Pix

    #57715 Reply
    Ambrish
    Guest

    Does A5/3 is reflecting in tems mobile after sucsesfully implement in ericsson BSC of version 07B.Can u please give some more knowladge about A5/3 chiphering.

    #57716 Reply
    bert
    Guest

    Hello Bonoatana

    after changing algorithm you need to update the IWD in the BTS
    that can be done by a unconditional load in the BTS

    #57717 Reply
    awais
    Guest

    algorithm of a5 is needed, can anyone give me..? regards

    #57718 Reply
    Bab
    Guest

    Hi Guys
    Currently we are applied A5/1 in our network,I have heard that there are some risks of being attacked by hackers.with considering higher security of A5/3 what is/are benefit and downward of A5/3 comparing to A5/1 ? dose it impact Core side? or just BTS side?

    #57719 Reply
    pix
    Guest

    hi,

    you must set your MSC to autorize the usage of A5/3 in the BSS. Other than that, no other problem.

    Also, to strengthen the A5/1 algo, you can activate the “LapDm filling with random bits” feature. It make sthe A5/1 much harder to crack !

    (reason : not all MS are A5/3 compatible, so even if you activate A5/3, you’ll stil get a lot of A5/1 in your bss)

    regards
    pix

    #57720 Reply
    Bab
    Guest

    Thanks for your sufficient explanation, mix of these two features is ideal but of course expensive 😉

    #57721 Reply
    pix
    Guest

    hi,

    you’re welcome

    the lapdm random filling is free of charge, and it is already done in UL by the MS itself (some of them anyway)

    the BSS feature allow to do the DL random filling as well.

    cheers
    pix

    #57722 Reply
    Taib
    Guest

    We are facing following handover problem when A5/3 was activated in test scenario.

    We have NSN core, Motorola BSS & NSN BSS

    Source Cell—-Target Cell—- Result

    Moto BTS (A5/3 enable)—-Nokia BTS (A5/3 disable)—-HO failure.

    Moto BTS (A5/3 disable)—–Nokia BTS (A5/3 disable)—–HO success.

    Nokia BTS (A5/3 disable)—–Moto BTS (A5/3 enable)—-HO Success.

    Nokia BTS (A5/3 disable)—-Moto BTS (A5/3 disable)—–Success.

    What could be the reason for the HO failure in the first scenario.

    Thanks & regards,

    #57723 Reply
    pix
    Guest

    hi,

    have you tried
    nokia = enabled to moto = disabled ?
    and from enable to enable ?

    in the scenario “HO from a5/3 disable to a5/3 enable”, what is the actual ciphering mode in the target cell ? does the MS stays in the a5/1, as it was in the previous cell, or does it move to a5/3 ?

    Your problem (no HO from a5/3 bss to a5/1 bss) could be analyzed by checking the HO REQUEST and HO REQUIRED message, in which you should find info about the ciphering algo chosen by serving BSC and by the MSC. If only A5/3 is shown in these messages, then of course it won’t work.

    regards
    pix

    #57724 Reply
    taib
    Guest

    Hi Pix,

    In Case of Nokia BTS, A5/3 is always disabled… But in Motorola A5/3 is enabled in the test scenario.

    In case of Moto Source cell HO required message it indicated A5/3 as the ciphering used, but in the HO acknowledge message from the Target Nokia BSS there is no indication of the Cipher field.

    Regards

    #57725 Reply
    pix
    Guest

    hi,

    i have to check when is the cipher mode decided during HO. Without any background about this, i’d say that you should check the HO REQUIRED sent from MSC to the Nokia BSC.
    The MSC should be aware of the cipher capabilities of the Nokia BSS and should negociate a5/1 instead of a5/3.

    As I’m on holidays, I’m not sure I can’t check this out right now 🙂

    Cheers
    pix

    #57726 Reply
    Vladmin
    Guest

    Hi everyone,

    Im a beginner in what this technology means so I’d like to get a bit more udnerstanding, if you could help me, Id really appreciate it.

    1. On 3G technology the A5/3 algorithm is being used. Does that mean that if I have a 2G SIM Card and I switch to a 3G one, Im safe and my phone won’t be hacked ?

    2. This algorithm, is it implemented at a SIM card level only or is in part of the MSC, towers, etc ?

Viewing 15 posts - 1 through 15 (of 19 total)
Reply To: A5/1 to A5/2 ciphering algorithm
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