Harald Welte laforge at
Sun Sep 20 11:55:54 UTC 2020

Dear Sergei,

I'm not an expert in GEA and it's been a long time since I last looked at it.


On Fri, Sep 18, 2020 at 12:53:43PM +0300, Сергей Егоров wrote:
> Can the value of IOV_UI (Osmocom BS: 0, real BS: 0x10000000) affect the deciphering, and if yes then how??

well, as you know the IV (initialization vector) is an input parameter into the 
encryption/decryption algorithm.  It must match, otherwise you will get completely
different results.

You could try to modify the Osmocom stack (here: OsmoSGSN) to also use the same IV
that you see in your commercial/production netwokr, and see if that gets you any
further in understanding any differences?

- Harald Welte <laforge at>  
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

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