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I am using a PN7150 and when it detects a TAG Mifare, I have to read the memory spaces. During authentication I planned to submit public keys before indicating access denied. Can you indicate me the documentation where I will be able to find the procedure which allows to submit several keys? especially the notions of time and intermediate exchanges if necessary. Thanks in advance.

fuz
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GRub
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  • How is this related to assembly? – fuz Jan 14 '21 at 13:41
  • There are a number of different Mifare Tags available, you need to specify the exact model and then you can look up the datasheet which will detail everything needed. – Andrew Jan 14 '21 at 13:45
  • I am using a Mifare Classic 1K tag. I did not find authentication using public keys in the documentation. With MCUXpresso IDE and the examples, we find a typical frame using the public key $ FF $ FF $ FF $ FF $ FF $ FF, followed by the request to read a sector / block but if the key is refused, it is not is there no explanation on how to submit other keys? – GRub Jan 14 '21 at 14:17
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    @fuz The whole application is written in assembler – GRub Jan 14 '21 at 14:19
  • @GRub Then please tag and mention the specific architecture and processor you are programming for in addition to the assembly tag. You can and are encouraged to [edit] your question at any time to add missing information. – fuz Jan 14 '21 at 14:24
  • Probably a duplicate with answer https://stackoverflow.com/a/56226964/2373819 This answer gives a link to an application note with more details on authentication and it give the only other "well known key" of `D3 F7 D3 F7 D3 F7` used to store NDEF messages on this type of Tag – Andrew Jan 14 '21 at 14:30
  • I am using a PIC18F47J53 microcontroller on a board we have developed. The discovery of TAGs and manipulations on UIDs work. To be able to use NFC, I have to offer clients the possibility of reading and writing in unlocked memory spaces. – GRub Jan 14 '21 at 14:32
  • @GRub Instead of making comments (which are easily overlooked), please [edit] your question to add these details and the corresponding tags. – fuz Jan 14 '21 at 14:36
  • @andrew This key is already transcribed among 8 others. If I give the accepted key first, then I can read. But if I put the correct key to another prosition in the list, it is refused. This tells me that it is my reiteration loop that is wrong and that is the information I am looking for. – GRub Jan 14 '21 at 14:38
  • As you show no code it is impossible to tell if your iteration loop is wrong but from https://www.nxp.com/docs/en/application-note/AN1304.pdf Section 6.4.1 there is a note saying "Each time an Authentication operation, a Read operation or a Write operation fails, the MIFARE Classic or MIFARE Plus remains silent and it does not respond anymore to any commands. In this situation in order to continue the NDEF Detection Procedure the MIFARE Classic or MIFARE Plus needs to be re-activated and selected." so you cannot try multiple auth attempts without doing some more work between each attempt – Andrew Jan 14 '21 at 15:37
  • @Fuz For my next topics, I will take care to stick to the essentials. Thank you anyway. – GRub Jan 15 '21 at 08:38

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From nxp.com/docs/en/application-note/AN1304.pdf Section 6.4.1 there is a note saying "Each time an Authentication operation, a Read operation or a Write operation fails, the MIFARE Classic or MIFARE Plus remains silent and it does not respond anymore to any commands. In this situation in order to continue the NDEF Detection Procedure the MIFARE Classic or MIFARE Plus needs to be re-activated and selected."

The datasheet for the tag https://www.nxp.com/docs/en/data-sheet/MF1S70YYX_V1.pdf in section 9.1 give the command codes need for selecting and halting the card.

The application note https://www.nxp.com/docs/en/application-note/AN10834.pdf gives you the process for selecting the card.

I'm not familar with the PN7150 or the micro controller you are using so I cannot give you code examples.

Andrew
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  • Thanks for the information, I will read or reread the indicated documentation. When a TAG is present, the presence control sequence must be done according to the protocol used. Often it is a function of rediscovery. I am thinking of following this trail to have the possibility of authenticating with another key. – GRub Jan 15 '21 at 08:34