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Code Issues Releases Wiki Activity

apps.fido_u2f: small changes in msg_register

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This commit is contained in:
Jan Pochyla 2017-05-30 19:07:20 +02:00
parent cd7ee79c67
commit 479ff127fc
1 changed files with 26 additions and 24 deletions
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50
src/apps/fido_u2f/__init__.py
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@ -347,45 +347,46 @@ _register_state = 0
async def msg_register(req: Msg) -> Cmd:
global _register_state
if len(req.data) != 64:
return msg_error(req, _SW_WRONG_LENGTH)
chal = req.data[:32]
app_id = req.data[32:]
from apps.common import storage
if not storage.is_initialized():
return msg_error(req, _SW_CONDITIONS_NOT_SATISFIED)
# check input data
if len(req.data) != 64:
return msg_error(req, _SW_WRONG_LENGTH)
# TODO: wait for a button press
if _register_state == 0:
_register_state = utime.ticks_ms()
if utime.ticks_ms() - _register_state < 2000:
if utime.ticks_ms() - _register_state < 500:
return msg_error(req, _SW_CONDITIONS_NOT_SATISFIED)
_register_state = 0
buf = msg_register_sign(chal, app_id, _U2F_ATT_CERT)
chal = req.data[:32]
app_id = req.data[32:]
buf = msg_register_sign(chal, app_id)
return Cmd(req.cid, _CMD_MSG, buf)
def msg_register_sign(challenge: bytes, app_id: bytes, cert: bytes) -> bytes:
def msg_register_sign(challenge: bytes, app_id: bytes) -> bytes:
from apps.common import seed
# derivation path is m/U2F'/r'/r'/r'/r'/r'/r'/r'/r'
key_path = [0x80000000 | random.uniform(0xf0000000) for _ in range(0, 8)]
node_path = [_U2F_KEY_PATH] + key_path
keypath = [0x80000000 | random.uniform(0xf0000000) for _ in range(0, 8)]
nodepath = [_U2F_KEY_PATH] + keypath
# prepare signing key from random path, compute decompressed public key
node = seed.get_root_without_passphrase('nist256p1')
node.derive_path(node_path)
node.derive_path(nodepath)
pubkey = nist256p1.publickey(node.private_key(), False)
# first half of keyhandle is key_path
keybuf = ustruct.pack('>8L', *key_path)
# first half of keyhandle is keypath
keybuf = ustruct.pack('>8L', *keypath)
# second half of keyhandle is a hmac of app_id and key_path
# second half of keyhandle is a hmac of app_id and keypath
keybase = hmac.Hmac(node.private_key(), app_id, hashlib.sha256)
keybase.update(keybuf)
keybase = keybase.digest()
@ -393,11 +394,11 @@ def msg_register_sign(challenge: bytes, app_id: bytes, cert: bytes) -> bytes:
# hash the request data together with keyhandle and pubkey
dig = hashlib.sha256()
dig.update(b'\x00') # uint8_t reserved;
dig.update(app_id) # uint8_t appId[U2F_APPID_SIZE];
dig.update(challenge) # uint8_t chal[U2F_CHAL_SIZE];
dig.update(keybuf) # uint8_t keyHandle[KEY_HANDLE_LEN];
dig.update(app_id) # uint8_t appId[32];
dig.update(challenge) # uint8_t chal[32];
dig.update(keybuf) # uint8_t keyHandle[64];
dig.update(keybase)
dig.update(pubkey) # uint8_t pubKey[U2F_PUBKEY_LEN];
dig.update(pubkey) # uint8_t pubKey[65];
dig = dig.digest()
# sign the digest and convert to der
@ -405,15 +406,16 @@ def msg_register_sign(challenge: bytes, app_id: bytes, cert: bytes) -> bytes:
sig = der.encode_seq((sig[1:33], sig[33:]))
# pack to a response
buf, resp = make_struct(resp_cmd_register(len(keybuf) + len(keybase), len(cert), len(sig)))
buf, resp = make_struct(resp_cmd_register(
len(keybuf) + len(keybase), len(_U2F_ATT_CERT), len(sig)))
resp.registerId = _U2F_REGISTER_ID
resp.status = _SW_NO_ERROR
resp.keyHandleLen = len(keybuf) + len(keybase)
utils.memcpy(resp.cert, 0, cert, 0, len(cert))
utils.memcpy(resp.pubKey, 0, pubkey, 0, len(pubkey))
resp.keyHandleLen = len(keybuf) + len(keybase)
utils.memcpy(resp.keyHandle, 0, keybuf, 0, len(keybuf))
utils.memcpy(resp.keyHandle, len(keybuf), keybase, 0, len(keybase))
utils.memcpy(resp.cert, 0, _U2F_ATT_CERT, 0, len(_U2F_ATT_CERT))
utils.memcpy(resp.sig, 0, sig, 0, len(sig))
resp.status = _SW_NO_ERROR
return buf