Scanning

Read GhostESP-compatible NFC tags and understand the on-screen feedback

Prerequisites

  • GhostESP firmware compiled with NFC support and a connected PN532 module, ST25R3916 module, or chameleon ultra.
  • (Optional) SD card if you plan to save tag dumps.

Backend Selection

If both a PN532 and an ST25R3916 are fitted, pick which one drives scans:

  • UI: the NFC menu has a Backend row that cycles auto -> pn532 -> st25r.
  • CLI: nfc backend auto, nfc backend pn532, or nfc backend st25r.

auto tries the PN532 first, then the ST25R3916. For MIFARE Classic dictionary brute-force the PN532 is noticeably faster because it has hardware Crypto1; the ST25R3916 does the same auth in software. Keep that in mind if brute-force feels slow - switch to pn532 (or auto) when you just need a dump.

Steps

  1. Open Scan. Pick Scan in the NFC menu; the popup shows “Scanning NFC…” while the PN532 spins up.

  2. Bring in a tag. Place it flat on the antenna. The UID, ATQA, and SAK appear immediately; Classic cards flip the title to “Bruteforcing keys… 0%”.

  3. Hold steady. Keep the tag still while reads finish. If the tag slips away, the UI pauses and prompts you to return it before resuming.

  4. Check output. Review the summary, toggle More for more info, and use Save to write the dump once “NFC Tag” is displayed.

Auto-Pause Detection

  • The scanner polls for the tag continuously. If it leaves the field mid-scan, the UI enters a paused state, disables brute-force attempts, and resumes automatically once the same UID is back in range.

MIFARE Classic Flow

  • Dictionary attack order: GhostESP tries user keys, then common keys, then the Flipper dictionary.

  • Caching behavior. Once a sector unlocks, its blocks and both Key A/Key B values are cached. The title shifts to “Reading sectors…” during the copy. Successful keys are appended back to the user dictionary on the SD card.

  • Magic backdoor tags. If the card supports the classic backdoor sequence, GhostESP logs the detection and can skip sector authentication, pulling data directly.

  • Nested key recovery (ST25R3916 only). When at least one key is known and another is missing, the ST25R3916 software Crypto1 path captures encrypted nested nonces and their parity bits, then tests the dictionaries locally against those constraints instead of doing one RF auth per candidate. This is much faster than a plain brute-force when a key exists somewhere on the card. The PRNG is classified weak vs hard automatically:

    • Weak PRNG cards need only a couple of samples; decrypted nonces must satisfy the weak 16-bit PRNG relation.
    • Hard PRNG cards require more samples and the recovered candidate is RF-verified before being trusted.

  • Nested log export. If local recovery cannot fully solve the card, GhostESP appends a Momentum-compatible line to /mnt/ghostesp/nfc/.nested.log so you can finish the crack on a PC with your normal hardnested solver. The on-screen summary notes whether the nested log was written.

  • Skip option: Tap Skip to bypass dictionaries when you only need public sectors.

  • After the scan. The more summary lists recovered sectors and keys as well as any detected NDEF data.

NTAG / Ultralight Flow

  • Immediate reads. NTAG21x and Ultralight tags are readable without keys, so the title stays “Scanning NFC…” until the UID appears, then flips to “NFC Tag”.

  • Page sweep. The reader streams all user pages, signature bytes, and counters if present. Progress is shown via the page counter in the popup body.

  • NDEF parsing. Detected TLVs are decoded into text, URI, or custom payload summaries. Tap More to see the raw TLV breakdown.

  • Caching and saves. All pages remain in RAM for the current session; saving writes the entire image to /mnt/ghostesp/nfc/<Model>_<UID>.nfc for later writes.

  • Verification. Re-scan immediately after to confirm the data matches or to check the signature for authenticity.

Chameleon Ultra Scanning

  • Connect first. Complete the Chameleon Ultra setup so GhostESP is paired over BLE.
  • Switch to reader. Run chameleon reader in the CLI; the terminal confirms the device is ready to scan.
  • Start HF scans. Use chameleon scanhf while holding the tag near the Chameleon Ultra antenna. The CLI mirrors the familiar popup summaries, including brute-force percentages for MIFARE Classic cards.
  • Start LF scans. Use chameleon scanlf (or scanlfall to sweep profiles) for low-frequency tags; results appear in the CLI and the on-device terminal view.
  • Reuse cached data. Once a scan finishes, you can proceed directly to the save flow without rescanning on the PN532.

Verify

  • Confirm the tag type and UID shown on-screen match the physical tag you scanned.
  • For Mifare Classic cards, check the listed sectors to see how many keys were recovered.
  • If you saved the capture, verify a new <Model>_<UID>.nfc file was created under /mnt/ghostesp/nfc/.

Troubleshooting

  • No change from “Scanning NFC…”. Re-seat the tag and verify PN532 wiring; try another tag to rule out hardware issues.

  • Stuck on “Bruteforcing keys… 0%”. GhostESP is testing dictionaries. On the ST25R3916 this is slower than on the PN532 because auth runs in software; switch the backend to pn532 or auto for faster dictionary attacks, or use the Skip button if you only need publicly readable blocks.

  • UID reads but data is empty. The card may be write-protected or needs a key not present in your dictionaries. You can add it to your user dictionary in /mnt/ghostesp/nfc/mfc_user_dict.nfc and then try rescanning.

FAQ

  • Which keys does GhostESP try? Your session keys and User Dictionary run first, followed by the embedded common keys, default keys, and then the fallback SD dictionary.

  • What do the sector labels mean? Mifare Classic memory is split into numbered sectors, each protected by Key A and Key B. A listed sector means at least one key unlocked it during the scan.

  • Can I scan other tag families? NTAG21x and Ultralight tags read without needing a brute force; they show their NDEF TLVs immediately after the UID appears.