[Python] Trying to perform authentication over my NFC chip for passport/ID in Python

This is my code

import hashlib
import binascii
from smartcard.System import readers
from smartcard.util import toHexString
from Crypto.Cipher import DES3
from Crypto.Random import get_random_bytes

def compute_sha1(data):
sha1 = hashlib.sha1()
sha1.update(data.encode('ascii'))
return sha1.digest()

def adjust_parity(key):
adjusted_key = bytearray(key)
for i in range(len(adjusted_key)):
byte = adjusted_key & 0xFE
parity = 0
for bit in range(1, 8):
parity ^= (byte >> bit) & 0x01
adjusted_key = byte | (parity ^ 0x01)
return bytes(adjusted_key)

def derive_keys(mrz_info):
mrz_key_seed = mrz_info
sha1_hash = compute_sha1(mrz_key_seed)
k_enc = adjust_parity(sha1_hash[:8] + sha1_hash[8:16])
k_mac = adjust_parity(sha1_hash[8:16] + sha1_hash[:8])
return k_enc, k_mac

def encrypt_3des_cbc(key, iv, data):
cipher = DES3.new(key, DES3.MODE_CBC, iv)
return cipher.encrypt(data)

def compute_mac(k_mac, data):
cipher = DES3.new(k_mac, DES3.MODE_CBC, iv=b'\x00' * 8)
padded_data = data + b'\x80' + b'\x00' * (7 - (len(data) % 8))
mac = cipher.encrypt(padded_data)[-8:]
return mac

def compute_check_digit(data):
weights = [7, 3, 1]
total = 0
for i, char in enumerate(data):
if char.isdigit():
value = int(char)
elif char == '<':
value = 0
else:
value = ord(char) - 55
total += value * weights[i % 3]
return str(total % 10)


def main():
# this is the test codes but I'm actually using my real MRZ
doc_number = "L898902C3"
dob = "740812"
doe = "120415"

mrz_info = doc_number + compute_check_digit(doc_number) + dob + compute_check_digit(dob) + doe + compute_check_digit(doe)

# Derive keys
k_enc, k_mac = derive_keys(mrz_info)
print(f"Kenc: {toHexString(list(k_enc))}")
print(f"Kmac: {toHexString(list(k_mac))}")

# Generate random numbers
rnd_ifd = get_random_bytes(8)
rnd_ic = get_random_bytes(8)
k_ifd = get_random_bytes(8)
print(f"rnd_ifd: {toHexString(list(rnd_ifd))}")
print(f"rnd_ic: {toHexString(list(rnd_ic))}")
print(f"k_ifd: {toHexString(list(k_ifd))}")

# Construct S and encrypt it
s = rnd_ifd + rnd_ic + k_ifd
encrypted_s = encrypt_3des_cbc(k_enc, b'\x00' * 8, s)
print(f"encryptedS: {toHexString(list(encrypted_s))}")

# Compute MAC
mac = compute_mac(k_mac, encrypted_s)
print(f"MAC: {toHexString(list(mac))}")

# Construct APDU
apdu = b'\x00\x82\x00\x00\x20' + encrypted_s + mac
print(f"APDU: {toHexString(list(apdu))}")

# Select reader and connect to card
r = readers()
if len(r) == 0:
print("Oops")
return
reader = r[0]
connection = reader.createConnection()
connection.connect()

# Select MF
select_mf = [0x00, 0xA4, 0x00, 0x00, 0x02, 0x3F, 0x00]
response, sw1, sw2 = connection.transmit(select_mf)
print(f"Select MF: {toHexString(list(response))} {sw1:02X} {sw2:02X}")

# Select LDS
select_lds = [0x00, 0xA4, 0x04, 0x0C, 0x07, 0xA0, 0x00, 0x00, 0x02, 0x47, 0x10, 0x01]
response, sw1, sw2 = connection.transmit(select_lds)
print(f"Select LDS: {toHexString(list(response))} {sw1:02X} {sw2:02X}")

# Get Challenge
get_challenge = [0x00, 0x84, 0x00, 0x00, 0x08]
response, sw1, sw2 = connection.transmit(get_challenge)
print(f"Get Challenge: {toHexString(list(response))} {sw1:02X} {sw2:02X}")

# External Authenticate
response, sw1, sw2 = connection.transmit(list(apdu))
print(f"External Authenticate: {toHexString(list(response))} {sw1:02X} {sw2:02X}")


if __name__ == "__main__":
main()


Every attempt to work with the passport results in 67 00 response, using my ACR122 USB NFC reader.

The idea is to get the NFC data (photo etc) from the passport. Why the code returns me invalid length?

Continue reading...