Regarding A5/3 KASUMI in GSM (2G)

[Abracadabra Abracadabra]

Hi all,

Using grgsm_capture to get 2g encrypted packets. On decoding these using grgsm_decode on the SDCCH8 I get CMC( Ciphering Mode Command) with cipher being used as A5/3 (2) for voice calls. There is no encryption for sms

Is there a way to decrypt the A5/3 for voice ? Any tools or methods to get the voice message decoded ?

I need to decrypt it for my college project

Any help appreciated 

Warm regards

Abracadabra 

[Nikos Balkanas]

Hi,

SMS may use optional WTLS encryption. grgsm doesn't understand it.
Not all SMS use that. For more information check www.kannel.org.

BR
Nikos

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[Nikos Balkanas]

Hi,

Sorry about the confusion. Thought you were having problems with SMS.
A5/3 is the kasumi cipher.
grgsm supports only the a5/1:(
In contradiction to the A5/1 cipher that was kept secret, and had to be hacked,
they decided all future ciphers to be published open.
You can find the cipher/decipher code for it in many places, like in openBTS.
Do you have the key?

HTH
Nikos

[Nikos Balkanas]

Hi,

This is what you can do with it:
1) Copy the source code and compile the kasumi encrypt/decrypt.
2) Save that packet data from wireshark
3) Input that to your decrypt program, along with the key
4) Play output in your gsm audio:)

HTH
Nikos