Magcard Write Read Utility Program -

def decode_track(encoded): """Extracts raw data and verifies LRC""" if len(encoded) < 4: return None # Expected format: S data E checksum start_sentinel = encoded[0] end_sentinel = encoded[-2] checksum = encoded[-1] data_part = encoded[1:-2]

It simulates the low-level track data manipulation for magnetic stripe cards (tracks 1, 2, 3) as per ISO 7811, and includes functions to , write , encode , and decode card data.

# Interactive mode card = MagCard() print("\n===== MagCard Utility (Simulated) =====") print("Commands: w(rite), r(ead), d(isplay), c(lear), q(uit)\n") while True: cmd = input("> ").strip().lower() if cmd == 'q': break elif cmd == 'w': interactive_write(card) elif cmd == 'r': interactive_read(card) elif cmd == 'd': display_card(card) elif cmd == 'c': card.clear() print("Card cleared.") else: print("Unknown command. Try w, r, d, c, q.") if == " main ": main() How to use it 1. Interactive mode Run the script with no arguments: magcard write read utility program

TRACK_MAX_LEN = 1: 79, 2: 40, 3: 107 class MagCard: def init (self): self.track1 = "" self.track2 = "" self.track3 = ""

def write_track(self, track_num, data): if not self.is_valid_track(track_num, data): raise ValueError(f"Invalid data for track track_num. Length or character mismatch.") if track_num == 1: self.track1 = data elif track_num == 2: self.track2 = data elif track_num == 3: self.track3 = data else: raise ValueError("Track must be 1, 2, or 3") Interactive mode Run the script with no arguments:

def clear(self): self.track1 = "" self.track2 = "" self.track3 = "" def encode_track(data, start_sentinel='%', end_sentinel='?'): """Adds start/end sentinels and LRC (simple XOR checksum)""" lrc = 0 for ch in data: lrc ^= ord(ch) checksum_char = chr(lrc % 128) # simple printable approximation return f"start_sentineldataend_sentinelchecksum_char"

For example, a USB keyboard wedge reader would just capture swiped data as if typed – no special driver needed. A writer would require sending track data in a proprietary command format over USB HID or serial. python magcard_util

python magcard_util.py --write "2:1234567890" Read track 1: