I made an app that writes data into NFC card (mifare classic) using key A and key B, key A was set to be 0xFFFFFFFFF (factory default) but for key B i use my custom key. Is there any way to hide key B from tools such as Mifare Classic Tool so it shows as --:--:--:--:--:--

using this one, I can freely write data inside sector (i set it as sector 2) but key A and key B is visible in MCT.

trailerData[6] = 0xFF.toByte()
trailerData[7] = 0x07.toByte()
trailerData[8] = 0x80.toByte()
trailerData[9] = 0x69.toByte()

using this one i can hide key B but i can only write once, after that my app shows a transceive error.

trailerData[6] = 0x7F.toByte()
trailerData[7] = 0x07.toByte()
trailerData[8] = 0x88.toByte()
trailerData[9] = 0x69.toByte()

what i want is, to set key B as hidden, but i can still write freely to my sector, what access bits that i need to change it to?

I made an app that writes data into NFC card (mifare classic) using key A and key B, key A was set to be 0xFFFFFFFFF (factory default) but for key B i use my custom key. Is there any way to hide key B from tools such as Mifare Classic Tool so it shows as --:--:--:--:--:--

using this one, I can freely write data inside sector (i set it as sector 2) but key A and key B is visible in MCT.

trailerData[6] = 0xFF.toByte()
trailerData[7] = 0x07.toByte()
trailerData[8] = 0x80.toByte()
trailerData[9] = 0x69.toByte()

using this one i can hide key B but i can only write once, after that my app shows a transceive error.

trailerData[6] = 0x7F.toByte()
trailerData[7] = 0x07.toByte()
trailerData[8] = 0x88.toByte()
trailerData[9] = 0x69.toByte()

what i want is, to set key B as hidden, but i can still write freely to my sector, what access bits that i need to change it to?

• nfc
• mifare

1 Answer 1

In the document named MF1S70YYX_V1 in section 8.7.2, you have a table with the access byte configuration information, from 6 to 9. There it explains the different values to make key b not visible.