5d4af2c8e4
First piece of Hitag support. Adds the Hitag2 48-bit stream cipher and a software-sim transponder/reader over SoftwareMedium (parity with the other LF tags). - hitag2_crypto.py: pure-Python port of the Proxmark reference cipher (firmware tools/hitag2crack/hitag2_gen_nRaR.py). Validated bit-for-bit against the classic MIKRON golden vector (keystream 0xD7237FCE, full 16-byte sequence). Hitag2Cipher wraps a running session (bits() for the authenticator, transcrypt() for link encryption). - hitag2.py: Hitag2Tag (8 x 32-bit pages, UID/key/config/password) and Hitag2Reader. Faithful UID request (5-bit START_AUTH), password-mode auth (page-1 RWD password), and crypto-mode auth (64-bit nR||aR + aR verify + transcrypt). Wrong key is rejected; UID page is read-only. Software-sim command framing between our own tag/reader; the crypto and auth handshake are bit-faithful to real tags. 12 tests. Hitag S / Hitag u, the reader client commands, and sniff/trace decode follow in subsequent commits. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
110 lines
3.7 KiB
Python
110 lines
3.7 KiB
Python
"""Hitag2 cipher + software-sim transponder/reader. Hardware-free."""
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import asyncio
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import pytest
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from pm3py.sim import SoftwareMedium, Hitag2Tag, Hitag2Reader
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from pm3py.transponders.lf.nxp.hitag2 import DEFAULT_KEY
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from pm3py.transponders.lf.nxp.hitag2_crypto import (
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hitag2_init, keystream, authenticator, Hitag2Cipher,
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)
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UID = b"\x11\x22\x33\x44"
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def run(coro):
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return asyncio.new_event_loop().run_until_complete(coro)
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# --- The MIKRON golden vector pins the cipher to the Proxmark reference (hitag2_gen_nRaR.py) ---
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class TestHitag2Cipher:
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def test_mikron_keystream(self):
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ks, _ = keystream(hitag2_init(0x4F4E4D494B52, 0x49435769, 0x656E4572), 32)
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assert ks == 0xD7237FCE
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def test_mikron_authenticator(self):
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assert authenticator(0x4F4E4D494B52, 0x49435769, 0x656E4572) == 0xD7237FCE
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def test_mikron_16_bytes(self):
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ks, _ = keystream(hitag2_init(0x4F4E4D494B52, 0x49435769, 0x656E4572), 128)
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assert ks.to_bytes(16, "big").hex().upper() == "D7237FCE8CD037A95749C1E648008AB6"
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def test_transcrypt_roundtrip(self):
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a = Hitag2Cipher(0x4F4E4D494B52, 0x49435769, 0x656E4572)
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b = Hitag2Cipher(0x4F4E4D494B52, 0x49435769, 0x656E4572)
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a.bits(32) # advance both past aR, identically
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b.bits(32)
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data = b"\xDE\xAD\xBE\xEF"
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enc = a.transcrypt(data)
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assert enc != data
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assert b.transcrypt(enc) == data # b decrypts what a encrypted
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async def _setup(**tag_kw):
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m = SoftwareMedium()
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tag = Hitag2Tag(uid=UID, key=DEFAULT_KEY,
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data=[b"AAAA", b"BBBB", b"CCCC", b"DDDD"], **tag_kw)
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await m.attach(tag)
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return m, tag, Hitag2Reader(m, key=DEFAULT_KEY)
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class TestHitag2Sim:
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def test_request_uid(self):
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async def go():
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_, _, r = await _setup()
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return await r.request_uid()
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assert run(go()) == UID
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def test_crypto_auth_success(self):
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async def go():
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_, _, r = await _setup(config=0x06)
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return await r.crypto_auth()
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page3 = run(go())
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assert page3 is not None
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assert page3[0] == 0x06 # decrypted config byte
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def test_crypto_auth_wrong_key(self):
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async def go():
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m, _, _ = await _setup()
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bad = Hitag2Reader(m, key=bytes(6))
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return await bad.crypto_auth()
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assert run(go()) is None
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def test_crypto_read_page(self):
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async def go():
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_, _, r = await _setup()
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await r.crypto_auth()
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return await r.read_page(4)
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assert run(go()) == b"AAAA" # transcrypt lockstep decrypts correctly
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def test_crypto_write_then_read(self):
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async def go():
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_, _, r = await _setup()
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await r.crypto_auth()
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ok = await r.write_page(5, b"WXYZ")
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return ok, await r.read_page(5)
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ok, val = run(go())
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assert ok is True and val == b"WXYZ"
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def test_read_requires_auth(self):
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async def go():
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_, _, r = await _setup()
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await r.request_uid() # no auth
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return await r.read_page(4)
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assert run(go()) is None
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def test_password_auth(self):
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async def go():
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_, _, r = await _setup(config=0x06)
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return await r.password_auth(DEFAULT_KEY[0:4]) # page 1 = key[0:4]
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page3 = run(go())
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assert page3 is not None and page3[0] == 0x06
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def test_uid_is_read_only(self):
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async def go():
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_, tag, r = await _setup()
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await r.crypto_auth()
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await r.write_page(0, b"\xFF\xFF\xFF\xFF") # must be rejected
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return tag.uid
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assert run(go()) == UID
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