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#1 2009-06-12 18:25:36

Sly
Contributor
Registered: 2009-03-02
Posts: 19

Understanding the Mifare Block and Using Crapto

Hey guys, kind of a new poster here, I just got my proxmarks last weekend and am fully set up with the 20081211 firmwares on Windows XP.

I've got the device working and all, but I am now having trouble with the snooping. I've looked at the guide here https://www.lafargue.name/article2752.html, I didn't find it all that helpful in trying to work out the different values needed for crapto to work out the key. Is it possible that with the following snooped data how I work it out? Is all the data recorded there ok or has the proxy not successfully caught all the bits needed.

already known : 72C73D6C

accessed block: S0 B0

recorded activity:
 ETU     :rssi: who bytes
---------+----+----+-----------
 +      0:    :     26    
 +     64:   0: TAG 04    
 +  40281:    :     93  20    
 +     64:   0: TAG 00!   
 +    134:   0: TAG 03!   
 +     56:   0: TAG 01    
 +  44429:    :     93  70  6c  3d  c7  72  e4  a3  2c    
 +     64:   0: TAG 08    
 +1908257:    :     26    
 +  16960:    :     26    
 +     64:   0: TAG 04    
 +     52:   0: TAG ff  03!   
 +  36783:    :     93  20    
 +     64:   0: TAG 04    
 +  43809:    :     93  70  6c  3d  c7  72  e4  a3  2c    
 +     64:   0: TAG 00!   
 +     54:   0: TAG 0f!   
 +  46333:    :     60  03  6e  49    
 +    112:   0: TAG 81!   
 +    284:   0: TAG 01    
 +   1228:    :     a0  69  41  bf  1e  f0  d3  fd      !crc
 +     64:   0: TAG 04    
 +  43001:    :     e1  e5  93  8b      !crc
 +     72:   0: TAG 01    
 +     78:   0: TAG 01    
 +  54141:    :     95  4a  5a  61      !crc
 +     72:   0: TAG 17!   
 +    157:   0: TAG 03!   
 +    160:   0: TAG 01    
 +    168:   0: TAG 03!   
 +    656:   0: TAG 01    
 +     56:   0: TAG 03!   
 +     48:   0: TAG 03!   
 +  52886:    :     92  16  40  bd      !crc
 +     72:   0: TAG 13    
 +    488:   0: TAG 02    
 +  53738:    :     d9  76  b9  48      !crc
 +     72:   0: TAG 00!   
 +     94:   0: TAG 01    
 +     38:   0: TAG 01    
 +     58:   0: TAG 01    
 +    136:   0: TAG 01    
 +    104:   0: TAG 03!   
 +     80:   0: TAG 01    
 +     64:   0: TAG 03!   
 +     48:   0: TAG 0f!   
 +     94:   0: TAG 03!   
 +     48:   0: TAG 07    
 +     80:   0: TAG ff!   
 +    186:   0: TAG 01    
 +     56:   0: TAG 03!   
 +     48:   0: TAG 07    
 +     64:   0: TAG 03!

I already know what the key is as I'm purely testing the device atm and I need to know if all the data is being recorded correctly between communicating with a blank card and reader.

P.S. Sorry If this is technically a repeat question of a previous thread.

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#2 2009-06-13 10:12:29

rule
Member
Registered: 2008-05-21
Posts: 417

Re: Understanding the Mifare Block and Using Crapto

I suggest that you first try to get a valid trace. If you can not eavesdrop the tag, check this explanation.

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#3 2009-06-13 15:43:40

Sly
Contributor
Registered: 2009-03-02
Posts: 19

Re: Understanding the Mifare Block and Using Crapto

roel wrote:

I suggest that you first try to get a valid trace. If you can not eavesdrop the tag, check this explanation.

Cheers Roel, I had a feeling that the data I sniffed was incomplete, hopefully I can work it out now

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#4 2009-06-13 18:32:07

hat
Contributor
Registered: 2009-04-12
Posts: 160

Re: Understanding the Mifare Block and Using Crapto

a shame though that after parsing the log it's clear you have the key still set to 0xffffffffffff
i should have just guessed that.

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#5 2009-06-13 19:42:51

Sly
Contributor
Registered: 2009-03-02
Posts: 19

Re: Understanding the Mifare Block and Using Crapto

hat wrote:

a shame though that after parsing the log it's clear you have the key still set to 0xffffffffffff
i should have just guessed that.

Yep, couldn't be arsed to change it.

How did you tell exactly? purely guessed or just recognised some of the traffic. I'd just be interested to get a better grip of all this.

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#6 2009-06-13 20:01:43

hat
Contributor
Registered: 2009-04-12
Posts: 160

Re: Understanding the Mifare Block and Using Crapto

there is enough information in the trace to retrieve the key. Mifare classic is just *that* weak.

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#7 2009-06-15 15:36:12

Sly
Contributor
Registered: 2009-03-02
Posts: 19

Re: Understanding the Mifare Block and Using Crapto

hat wrote:

there is enough information in the trace to retrieve the key. Mifare classic is just *that* weak.

So basically, you guessed but want to look all knowing.

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#8 2009-06-15 18:49:58

hat
Contributor
Registered: 2009-04-12
Posts: 160

Re: Understanding the Mifare Block and Using Crapto

who knows, why don't you arse yourself to set the key of the card to something unguessable

- keep the same UID, and sector (I am not it the i'll crack a key for ya business)
- create&post a similar log to the one above
- resist the urge to post random garbage(I'll call you on it)

Last edited by hat (2009-06-16 23:46:16)

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#9 2009-06-16 21:53:20

Sly
Contributor
Registered: 2009-03-02
Posts: 19

Re: Understanding the Mifare Block and Using Crapto

Yeh, I'll be happy to try and get the same kind of data again, but I don't want to waste my time.

Don't brag basically if your not going to explain how you can work out the key even from that amount of data. fair deal?

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#10 2009-06-16 23:45:36

hat
Contributor
Registered: 2009-04-12
Posts: 160

Re: Understanding the Mifare Block and Using Crapto

Sly wrote:

Yeh, I'll be happy to try and get the same kind of data again, but I don't want to waste my time.

Don't brag basically if your not going to explain how you can work out the key even from that amount of data. fair deal?

No,

- You just spend $500 on a proxmark you'll want to fix it so you have a duplex sniffer.
- You attacked my character and called me a liar
- You repeated the question posed in another thread (and
- You keep insisting how you're time is so valuable.
- You are not prepared to make a single trace to futher the conversation and perhaps infer details.
- I provided additional information, establishing that a problem is solvable is valuable information. Especially because one of your questions was "Is it possible that with the following snooped data how I work it out?".
- I didn't brag, I just presented you with a truth. And then taunted you. Which is more than allowable after you called me a liar.
==> In what universe do you think this could be a deal?


Here's my proposal, don't call me a liar without having the balls to stand by your claim. Perhaps you should stfu, and be grateful for the stuff that is available.

How is that for a deal?

frigging spoiled lazy bratz.

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#11 2009-06-17 07:58:06

Sly
Contributor
Registered: 2009-03-02
Posts: 19

Re: Understanding the Mifare Block and Using Crapto

For starters, after Roel's post I managed to make a decent trace and it was just a case of the antenna being a bit dodgy.

Secondly, in my last post I wasn't trying to be insulting, I was just saying that there's little point in producing another faulty log if all your going to do is tell me the key that I already know and not tell me how you're able to work it out and in my eyes someone telling someone else that 'there is an answer' is kind of a slap in the face when there's not even a hint given.

My point was to say, if I spend the time making another trace with a different key, will you at least point out some areas of how you did it rather than just say, 'the key is...'?

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#12 2009-06-17 11:28:29

rule
Member
Registered: 2008-05-21
Posts: 417

Re: Understanding the Mifare Block and Using Crapto

This community is about helping.... not bitching!

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