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MIFARE UID Byte Lengths

Question asked by Andrew Villagran on Nov 13, 2019
Latest reply on Nov 21, 2019 by Jonathan Iglesias

Hi, a client wants me to purchase 26-bit MIFARE DESFire cards, but I'm not sure if that's even a thing.  I've been reviewing this document: https://www.nxp.com/docs/en/application-note/AN10833.pdf (page 9), and it appears that each card format has a 4 or 7 byte portion for the UID (i.e. 32 or 56 bits), plus an extra portion of bytes for proprietary data.  For the UID, is it always 32 or 56 bits, or is there such a thing as 26-bit or 34-bit?  Also, is this the best document to use to understand the different MIFARE card formats, or is there something better?

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