NFC

GhostESP supports two NFC frontends, selectable at runtime:

• PN532 - the default reader. Fast hardware MIFARE Classic authentication, great for dictionary brute-force.
• ST25R3916/ST25R3916B - software-driven reader/emulator over SPI or I2C. Adds card emulation (Type 2 and MIFARE Classic) and software Crypto1 for nested/hardnested nonce capture.

Both share the same high-level scan/cache/save/write flow, so most of this section applies regardless of which module is fitted. Use the NFC menu Backend row (or nfc backend auto|pn532|st25r in the CLI) to switch.

• auto tries PN532 first, then ST25R3916.
• pn532 forces the PN532 path.
• st25r forces the ST25R3916 path. Emulation always forces ST25R3916 since the PN532 cannot emulate here.