MSID Decoding - GSM-Forum

VsH-GsM · 01-26-2002, 21:40

Hi, Here is some info,research to find algorithm for decoding msid to cobba id & ppm check... ***** MSID:=Function(CobbaID,PPM Check) Examples: ------------------------------------------------ PPMCheck Cobba ID MSID ------------------------------------------------ 14F8CD23 00F4ACF7 82 E5FB6F0F763BEBFBF4E6DF98 38FFFA09 00F4ACF7 82 00EAED6E7C20BA39FEA2A915 B5A9EE80 00F4ACF7 82 BEC4BD615D9E2E2201179B1D FFFFFFFF 00F4ACF7 82 0842D3CF1DE282FCA8B64593 00000000 00F4ACF7 82 D9F627377DF42926A2ACD63F 00000022 00F4ACF7 82 167D30E4D09524630E717206 00F4ACF7 00F4ACF7 82 0FD80CC384E82199C27DA00A 00000001 00F4ACF7 82 A83D52B5E6ECFA03BE5EFDFA 00000002 00F4ACF7 82 98DF5049177E7FBFF43E8930 00000003 00F4ACF7 82 330FF3A296D86FFF6E7CF0B0 11111111 00F4ACF7 82 9F38341F766BD3AB43745D7A 22222222 00F4ACF7 82 617951FD7CAE89F2EED892A3 ------------------------------------------------

gigaphreak · 01-27-2002, 00:45

thanks a lot for your hints vsh-gsm! but aren't there ppm check, cobba id and RANDOM BYTE for calculating msid?

Nick-A · 01-27-2002, 13:48

if you can give me as many samples of all the inputs for the FAID alogorithm, and the corresponding calculated FAID, I will pass them onto someone who can prob work it out,after all, its just a formula type thing right? will need quite a few though. Please email them to [email protected]

Nick

Lead · 01-28-2002, 09:56

Hi VsH-GSM, I think you're wasting your time in this case. It is absolutely useless to observe only a few input and output values since the FAID calculation function is nonlinear on finite rings. It could be possible to reverse-engineer the FAID calculation algorithm by disassembling the MCU, but I doubt the FAID verification algorithm is located in the MCU. I would guess it is located in the COBBA chip... <img src="frown.gif" border="0">

Best regards, Lead.

davieb · 01-28-2002, 16:37

argh! If only somoene would point us in the right directions... Dissasembly, algo "guessing", etc...

crusher · 01-28-2002, 21:07

I have doubts on that a DAC can have internal program memory for external usage <img src="smile.gif" border="0"> ))))

01-26-2002, 21:40	#1 (permalink)
VsH-GsM Banned Join Date: Nov 2001 Location: IRAN Age: 38 Posts: 3,679 Member: 7444 Status: Offline Sonork: 100.99999 Thanks Meter: 10,013	MSID Decoding Hi,<br />Here is some info,research to find algorithm for decoding msid to cobba id & ppm check...<br />*****<br />MSID:=Function(CobbaID,PPM Check)<br />Examples:<br />------------------------------------------------<br />PPMCheck Cobba ID MSID <br />------------------------------------------------<br />14F8CD23 00F4ACF7 82 E5FB6F0F763BEBFBF4E6DF98<br />38FFFA09 00F4ACF7 82 00EAED6E7C20BA39FEA2A915<br />B5A9EE80 00F4ACF7 82 BEC4BD615D9E2E2201179B1D<br />FFFFFFFF 00F4ACF7 82 0842D3CF1DE282FCA8B64593<br />00000000 00F4ACF7 82 D9F627377DF42926A2ACD63F<br />00000022 00F4ACF7 82 167D30E4D09524630E717206<br />00F4ACF7 00F4ACF7 82 0FD80CC384E82199C27DA00A<br />00000001 00F4ACF7 82 A83D52B5E6ECFA03BE5EFDFA<br />00000002 00F4ACF7 82 98DF5049177E7FBFF43E8930<br />00000003 00F4ACF7 82 330FF3A296D86FFF6E7CF0B0<br />11111111 00F4ACF7 82 9F38341F766BD3AB43745D7A<br />22222222 00F4ACF7 82 617951FD7CAE89F2EED892A3<br />------------------------------------------------

01-28-2002, 09:56	#4 (permalink)
Lead No Life Poster Join Date: Aug 2008 Age: 52 Posts: 3,292 Member: 1841 Status: Offline Thanks Meter: 469	Hi VsH-GSM, I think you're wasting your time in this case. It is absolutely useless to observe only a few input and output values since the FAID calculation function is nonlinear on finite rings.<br />It could be possible to reverse-engineer the FAID<br />calculation algorithm by disassembling the MCU, but I doubt the FAID verification algorithm is located in the MCU. I would guess it is located in the COBBA chip... <img src="frown.gif" border="0"> Best regards,<br />Lead.

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01-27-2002, 00:45	#2 (permalink)
gigaphreak Insane Poster Join Date: Feb 2001 Posts: 85 Member: 3397 Status: Offline Thanks Meter: 0	thanks a lot for your hints vsh-gsm! but aren't there ppm check, cobba id and RANDOM BYTE for calculating msid?

01-27-2002, 13:48	#3 (permalink)
Nick-A No Life Poster Join Date: Jan 2002 Posts: 519 Member: 8249 Status: Offline Thanks Meter: 2	if you can give me as many samples of all the inputs for the FAID alogorithm, and the corresponding calculated FAID, I will pass them onto someone who can prob work it out,after all, its just a formula type thing right? will need quite a few though. Please email them to [email protected] Nick

01-28-2002, 16:37	#5 (permalink)
davieb No Life Poster Join Date: May 2001 Location: Glasgow, Scotland Posts: 625 Member: 4690 Status: Offline Thanks Meter: 1	argh! If only somoene would point us in the right directions... Dissasembly, algo "guessing", etc...

01-28-2002, 21:07	#6 (permalink)
crusher No Life Poster Join Date: Dec 2001 Location: [winscard.SCardTransmit] Posts: 1,835 Member: 8023 Status: Offline Thanks Meter: 13	I have doubts on that a DAC can have internal program memory for external usage <img src="smile.gif" border="0"> ))))