From f6ae60147c58aee79a36c81b26f09980d71f7922 Mon Sep 17 00:00:00 2001
From: whaffman <whaffman@student.codam.nl>
Date: Thu, 3 Jul 2025 12:31:54 +0200
Subject: [PATCH] Add initial implementation of OTP generation and management
 script

---
 .gitignore |  2 ++
 ft_otp.py  | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 key.hex    |  1 +
 3 files changed, 74 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 key.hex

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a4be3b2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.venv/
+ft_otp.key
diff --git a/ft_otp.py b/ft_otp.py
index e69de29..837c757 100644
--- a/ft_otp.py
+++ b/ft_otp.py
@@ -0,0 +1,71 @@
+import argparse
+from cryptography.fernet import Fernet
+from hashlib import sha256
+from base64 import urlsafe_b64encode
+
+def main():
+	parser = argparse.ArgumentParser(description="Run the FT OTP script.")
+	parser.add_argument("-g", metavar="hexfile", type=str, help="Generate a new OTP key and save it to the specified file.")
+	parser.add_argument("-k", metavar="keyfile", type=str, help="Generate a OTP from the specified key file.")
+	args = parser.parse_args()
+
+	if args.g:
+		# Call the function to generate a new OTP key
+		generate_otp_key(args.g)
+	elif args.k:
+		# Call the function to generate a OTP from the specified key file
+		generate_otp_from_key(args.k)
+	else:
+		print("No action specified. Use -g to generate a new OTP key or -k to generate a OTP from a key file.")
+		parser.print_help()
+
+def generate_otp_key(hexfile):
+	print(f"Generating OTP key from {hexfile}...")
+	machine_id = get_machine_hash()
+	with open(hexfile, 'rb') as f:
+		hex_key = f.read().strip()
+	fernet = Fernet(machine_id)
+	otp_key = fernet.encrypt(hex_key)
+	with open('./ft_otp.key', 'wb') as f:
+		f.write(otp_key)
+
+def generate_otp_from_key(keyfile):
+	import time
+	machine_id = get_machine_hash()
+	with open(keyfile, 'rb') as f:
+		otp_key = f.read().strip()
+	fernet = Fernet(machine_id)
+	otp = fernet.decrypt(otp_key)
+	counter = int(time.time() // 30)  # Using time-based counter for HOTP
+	otp = HOTP(otp, counter)
+	# Print the generated OTP
+	print(f"Generated OTP: {otp}")
+
+def get_machine_hash() -> bytes:
+	"""Retrieve the machine ID from /etc/machine-id."""
+	try:
+		with open('/etc/machine-id', 'r') as f:
+			machine_id =  f.read().strip()
+		sha256_hash = sha256(machine_id.encode()).digest()
+		return urlsafe_b64encode(sha256_hash)
+	except FileNotFoundError:
+		print("Machine ID file not found. Please ensure the system is properly configured.")
+		return None
+
+
+
+def HOTP(key, counter):
+	"""Generate a one-time password using the HOTP algorithm. using RFC4226"""
+	import hmac
+	import struct
+	import hashlib
+
+	counter = struct.pack('>Q', counter)
+	hmac_hash = hmac.new(key, counter, hashlib.sha1).digest()
+	offset = hmac_hash[-1] & 0x0F
+	otp = (struct.unpack('>I', hmac_hash[offset:offset + 4])[0] & 0x7FFFFFFF) % 1000000
+	return str(otp).zfill(6)
+
+
+if __name__ == "__main__":
+	main()
\ No newline at end of file
diff --git a/key.hex b/key.hex
new file mode 100644
index 0000000..63aa3d4
--- /dev/null
+++ b/key.hex
@@ -0,0 +1 @@
+d779574a5815a54089b260694be7b29838e28a72e943bdd41e47656885118c7a3f29f6611ca1383f7e67e9868a80b8fd68c71be79b418e8984bdaef4991932e4