Important information regarding 4 Byte
and 7 Byte UIDs of MIFARE products
NXP Semiconductors would like to raise your attention concerning the consumption of unique identifier numbers (UIDs) with length of 4 Byte (B) for its MIFARE Classic smart card ICs and emulations.
With the accumulated and estimated global demand of MIFARE Classic ICs from NXP and its licensees, the market will run out of 4 Byte unique IDs. Successor products are being offered with 7 Byte UID as the recommended option and products with 4 Byte identifiers.
In addition we have prepared a document containing frequently asked questions and answers on the topic.
Further information can be found under UID Migration Webinar slides.
An overview about the product replacement can be found here.
For more technical information, please see the NXP Application Note 'MIFARE and handling of UIDs'.