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#1 2020-04-17 03:02:48

guew
Contributor
Registered: 2020-04-16
Posts: 2

Question on "Parity weakness".

I implemented crypto1, based on paper "Wirelessly Pickpocketing a Mifare Classic Card", on a 8-bit MCU with RC522(automatic parity generation off) reader. Everything is fine from request to authentication.

For authentication, I have:
Reader: Auth block0.
Tag:       Nt //4 bytes tag nonce with parity bits.
Reader: {Nr0, Nrp0, Nr1, Nrp1, Nr2, Nrp2, Nr3, Nrp3, Ar0, Arp0, Ar1, Arp1, Ar2, Arp2, Ar3, Arp3} //Nrn and Arn are reader nonce and response bytes, Nrpn and Arpn are parity bits.   
Tag:       {At} //4 bytes tag response with parity bits..
Above authentication process works correct.

When I try to repeat section3.1"Parity weakness" on page 6 of paper, I manually change Arn, like Arn += 1, and keep Arpn touched, the tag suppose to send back 4-bit error code 0x5.  But the tag keep quiet and refuse to give any answer.

Is my process wrong or this "Parity weakness" bug is fixed in nowdays(the paper pulished 12 years ago.) tag?

Last edited by guew (2020-04-17 03:07:48)

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#2 2020-04-17 05:16:53

iceman
Administrator
Registered: 2013-04-25
Posts: 9,497
Website

Re: Question on "Parity weakness".

[moved]

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