I am experimenting with NFC Tags and automation on Home Assistant. I have bought a few writeable NFC tags for these experiments. They are cheap, but I wouldn’t say I like wasting them while testing.
Since Flipper Zero can simulate NFC tags, I decided to use it for my tests.
If you want to do the same, here is what you need to do.
Flipper Zero stores NFC Tag data in a plain text file with a .nfc extension. There is a simple command line python script that allows you to write an NFC tag in the Flipper Zero format. Thank you to evilpete for making this available.
#!/usr/bin/env python
"""
Generates NFC with URL address data and outputs Flipper NFC "save" file
this is a 5 min hack, No Guarantees
./nfc_gen_url.py https://youtu.be/dQw4w9WgXcQ "Rick Roll" > rickroll.nfc
requires ndeflib
Written By: Peter Shipley github.com/evilpete
From pkg https://github.com/evilpete/flipper_toolbox
"""
import sys
try:
import ndef
except ImportError as e:
print("Failed to import ndef")
print("https://github.com/nfcpy/ndeflib")
sys.exit(0)
# make sure output is utf-8
sys.stdout.reconfigure(encoding='utf-8')
# for debuging
verbose = 0
nfc_header = """Filetype: Flipper NFC device
Version: 2
# generated with flipper_toolbox
Device type: NTAG215
# UID, ATQA and SAK are common for all formats
UID: 04 10 56 01 74 48 03
ATQA: 44 00
SAK: 00
# Mifare Ultralight specific data
Signature: A5 80 A4 CC A0 C3 A1 F6 8B BE 6F EE 83 A6 B9 EE 36 F8 FB C8 14 5A 23 AA 29 DB 78 56 07 B9 6B 92
Mifare version: 00 04 04 02 01 00 11 03
Counter 0: 0
Tearing 0: 00
Counter 1: 0
Tearing 1: 00
Counter 2: 0
Tearing 2: 00
Pages total: 135
"""
data_static = [
0x04, 0x10, 0x56, 0xCA, # 01 serial number
0x01, 0x74, 0x48, 0x03, # 02 serial number
0x3E, 0x48, 0x00, 0x00, # 03 serial number, internal, lock bytes, lock bytes
0xE1, 0x10, 0x3E, 0x00, # 04 Capability Container
]
conf_pages = [
0x00, 0x00, 0x00, 0xBD, # 130
0x04, 0x00, 0x00, 0xFF, # 131
0x00, 0x05, 0x00, 0x00, # 132
0x00, 0x00, 0x00, 0x00, # 133
0x00, 0x00, 0x00, 0x00, # 134
]
def print_nfc_sub(t_data, file=sys.stdout):
print(nfc_header, end='', file=file)
p = 0
for x in range(0, 540, 4):
print(f"Page {p}: {t_data[x]:02X} {t_data[x + 1]:02X} "
f"{t_data[x + 2]:02X} {t_data[x + 3]:02X}", file=file)
p = p + 1
def gen_nfc_sub(tag_data):
tag_message = []
data_list = []
for x in tag_data:
if x[0] == 'txt':
tag_message.append(ndef.TextRecord(x[1], "en"))
elif x[0] == 'url':
tag_message.append(ndef.UriRecord(x[1]))
if verbose:
print(x, file=sys.stderr)
print(tag_message[-1:], file=sys.stderr)
buf = b"".join((ndef.message_encoder(tag_message)))
m_len = len(buf)
if verbose:
print("buf", m_len, hex(m_len), buf, file=sys.stderr)
data_list.extend(data_static)
data_list.append(3) # Message Flags
if m_len < 255:
data_list.append(m_len) # Type Length
else:
data_list.append(0xFF)
lenStr = hex(m_len)[2:].rjust(4, "0")
data_list.append(int(lenStr[0:2], 16))
data_list.append(int(lenStr[2:4], 16))
data_list.extend(list(buf))
data_list.append(0xFE) # end of Data
data_len = len(data_list)
if verbose:
print("data_list", data_len, data_list, file=sys.stderr)
x = 520 - data_len
data_list.extend([0] * x)
data_list.extend(conf_pages)
return data_list
# url_str = "https://youtu.be/dQw4w9WgXcQ"
# title_str = "Rick Roll"
if __name__ == '__main__':
arg_data = []
for a in sys.argv[1:]:
if a.startswith("http"):
arg_data.append(("url", a))
else:
arg_data.append(("txt", a))
if not arg_data:
print("requires at least one URL argument\n"
"Please provide URL and optional Title\n\n"
f"{sys.argv[0]} : https://some.url 'Title'")
sys.exit()
nfc_data = gen_nfc_sub(arg_data)
print_nfc_sub(nfc_data)
sys.exit()
Copy the script on your computer (e.g. nfcdata.py) and run it:
python3 nfcdata.py "Test data"
This will create a file that you can upload to your Flipper Zero using the qFlipper desktop application.
You will now be able to emulate the tag on the Flipper Zero.