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How to set access bits and security keys for each sector of MIFARE 1K card with µFR Card Formatter software?

µFR Card Formatter GUI displays the entire MIFARE® Classic 1K structure with simple access to all its sectors and blocks ( 16 sectors of 4 blocks). The first block (block zero) contains the card factory UID, ad it is read-only by default. As for the rest of the card memory, it comes completely blank and access-free.  For each memory block, you can definable the custom access conditions. Also, with this software, you can define the additional security by assigning the Reader Key for the programmed cards. This means that all other readers (without a valid Security Key) will not be able to access the card data.

The empty card content and structure interface looks like this:


At the top left, the card content s displayed, and in this case, the entire card memory is blank, except ic factory UID stored in the first card block (block 0). Depending on the card series, the first 4 or 7 bytes contain the card UID. Unlike other sectors that contain 3 blocks and 16bytes, Sector 0 has only 2 blocks, the zero block with card UID, and the block with the manufacturer data (all read-only). This data can be read and saved into some log file, but you cannot edit or clone the card UID (at least, not legally). 

Let’s now move to the other writable parts of the card memory. Whether you’re writing or reading a card, all user-defined content will be displayed in the fields under the read line.


If you find it difficult to enter the card content through this interface, you may use any other Digital Logic tool for card writing, and then just read the content, store it into the file or use it for new card programming.

To create a new card with the same content, you can use the same Keys and settings as for the “original”, but you can also define the custom authentication for every card, or for the part of the copied content. This is provided by specified Key A and Key B, and the defined sector trailer for each card block. The sector trailer is the last block (block 3) in one sector and it contains the secret Key A, optional Key B, and the access conditions for the blocks of that sector (also specify the data blocks type, data, or value).

Byte Number 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Description KEY A Access Bits KEY B (optional)

If the Key B is not in use, the last 6 bytes of the sector trailer can be used as data bytes.

To define Key A and optionally Key B, with this software you can assign the Keys for the selected sectors and blocks:


To configure the access bit value for each sector trailer, enter the values into the bottom-left software panel:


To assign the desired access bit value, please check the Mifare® structure – card programming help.

Note: Access Conditions defined by the access bit values define the block/sector behavior. This is particularly important when it comes to specific blocks of access. Make sure that you defined these values carefully to prevent card permanent damage.