async def process_host_command(self, stream, show_fn):
"""
If command with one of the prefixes is received
it will be passed to this method.
Should return a tuple:
- stream (file, BytesIO etc)
- meta object with title and note
"""
# reads prefix from the stream (until first space)
prefix = self.get_prefix(stream)
if prefix != b"getrandom":
# WTF? It's not our data...
raise AppError("Prefix is not valid: %s" % prefix.decode())
# by default we return 32 bytes
num_bytes = 32
try:
num_bytes = int(stream.read().decode().strip())
except:
pass
if num_bytes < 0:
raise AppError("Seriously? %d bytes? No..." % num_bytes)
if num_bytes > 1000:
raise AppError("Sorry, 1k bytes max.")
obj = {"title": "Here is your entropy", "note": "%d bytes" % num_bytes}
return BytesIO(hexlify(get_random_bytes(num_bytes))), obj
def load_enc_secret(self):
fpath = self.path + "/enc_secret"
if platform.file_exists(fpath):
_, secret = self.load_aead(fpath, self.pin_secret)
else:
# create new key if it doesn't exist
secret = get_random_bytes(32)
self.save_aead(fpath, plaintext=secret, key=self.pin_secret)
self.enc_secret = secret
def create_new_secret(self, path):
"""Generate new secret and default PIN config"""
# generate new and save
secret = get_random_bytes(32)
# save secret
with open(path + "/secret", "wb") as f:
f.write(secret)
self.secret = secret
return secret
def __init__(self, title="Enter your PIN code", note=None, get_word=None, subtitle=None):
super().__init__()
self.title = add_label(title, scr=self, y=PADDING, style="title")
if subtitle is not None:
lbl = add_label(subtitle, scr=self, style="hint")
lbl.set_recolor(True)
lbl.align(self.title, lv.ALIGN.OUT_BOTTOM_MID, 0, 10)
if note is not None:
lbl = add_label(note, scr=self, style="hint")
lbl.align(self.title, lv.ALIGN.OUT_BOTTOM_MID, 0, 180)
self.get_word = get_word
if get_word is not None:
self.words = add_label(get_word(b""), scr=self)
self.words.align(self.title, lv.ALIGN.OUT_BOTTOM_MID, 0, 210)
btnm = lv.btnm(self)
# shuffle numbers to make sure
# no constant fingerprints left on screen
buttons = ["%d" % i for i in range(0, 10)]
btnmap = []
for j in range(3):
for i in range(3):
v = rng.get_random_bytes(1)[0] % len(buttons)
btnmap.append(buttons.pop(v))
btnmap.append("\n")
btnmap = btnmap + [lv.SYMBOL.CLOSE, buttons.pop(), lv.SYMBOL.OK, ""]
btnm.set_map(btnmap)
btnm.set_width(HOR_RES)
btnm.set_height(HOR_RES)
btnm.align(self, lv.ALIGN.IN_BOTTOM_MID, 0, 0)
# increase font size
style = lv.style_t()
lv.style_copy(style, btnm.get_style(lv.btnm.STYLE.BTN_REL))
style.text.font = lv.font_roboto_28
# remove feedback on press to avoid sidechannels
btnm.set_style(lv.btnm.STYLE.BTN_REL, style)
btnm.set_style(lv.btnm.STYLE.BTN_PR, style)
self.pin = lv.ta(self)
self.pin.set_text("")
self.pin.set_pwd_mode(True)
style = lv.style_t()
lv.style_copy(style, styles["theme"].style.ta.oneline)
style.text.font = lv.font_roboto_28
style.text.color = styles["theme"].style.scr.text.color
style.text.letter_space = 15
self.pin.set_style(lv.label.STYLE.MAIN, style)
self.pin.set_width(HOR_RES - 2 * PADDING)
self.pin.set_x(PADDING)
self.pin.set_y(PADDING + 50)
self.pin.set_cursor_type(lv.CURSOR.HIDDEN)
self.pin.set_one_line(True)
self.pin.set_text_align(lv.label.ALIGN.CENTER)
self.pin.set_pwd_show_time(0)
self.pin.align(btnm, lv.ALIGN.OUT_TOP_MID, 0, -150)
btnm.set_event_cb(feed_rng(self.cb))
def encrypt(plain: bytes, key: bytes) -> bytes:
"""Encrypt data with bit padding (0x80...)"""
iv = rng.get_random_bytes(IV_SIZE)
crypto = aes(key, AES_CBC, iv)
# encrypted data should be mod 16 (blocksize)
# add padding
plain += b'\x80'
if len(plain) % AES_BLOCK != 0:
# fill with zeroes
plain += b"\x00" * (AES_BLOCK - (len(plain) % AES_BLOCK))
return iv + crypto.encrypt(plain)
def create_new_secret(self, path):
"""Generate new secret and default PIN config"""
# generate new and save
secret = get_random_bytes(32)
# save secret
with open(path + "/secret", "wb") as f:
f.write(secret)
# set pin object
self.pin = None
self._pin_attempts_max = 10
self._pin_attempts_left = 10
self.secret = secret
self.save_state()
return secret
def set_pin(self, pin):
"""Saves hmac of the PIN code for verification later"""
# set up pin
key = tagged_hash("pin", self.secret)
self.pin = hmac.new(key=key, msg=pin, digestmod="sha256").digest()
self.pin_secret = tagged_hash("pin", self.secret + pin.encode())
self.save_state()
# update encryption secret
if self.enc_secret is None:
self.enc_secret = get_random_bytes(32)
self.save_aead(self.path + "/enc_secret",
plaintext=self.enc_secret,
key=self.pin_secret)
# call unlock now
self.unlock(pin)
def load_enc_secret(self):
data = self.applet.get_secret()
# no data yet
if len(data) == 0:
# create new key if it doesn't exist
secret = get_random_bytes(32)
# format: magic, 01 len enc_secret, 02 len entropy
d = self.serialize_data({"enc": secret})
self.applet.save_secret(d)
self._is_key_saved = False
else:
try:
d = self.parse_data(data)
secret = d["enc"]
if "entropy" in d:
self._is_key_saved = True
except KeyStoreError as e:
# wrong data on the card - not a big deal
# just generate a new key
self.enc_secret = get_random_bytes(32)
self._is_key_saved = False
# notify the user about the error
raise e
self.enc_secret = secret
def save_entropy_encrypted():
try:
Key.iv = get_random_bytes(16)
entropy_encrypted = entropy_encrypt(entropy)
hmac_entropy_encrypted = hmac_sha512(Key.key, entropy_encrypted)
obj = {
"entropy": hexlify(entropy_encrypted).decode('utf-8'),
"iv": hexlify(Key.iv).decode('utf-8'),
"hmac": hexlify(hmac_entropy_encrypted).decode('utf-8')
}
with open(reckless_fname, "w") as f:
f.write(json.dumps(obj))
with open(reckless_fname, "r") as f:
d = json.loads(f.read())
if "entropy" in d and d["entropy"] == hexlify(entropy_encrypted).decode('utf-8') and \
unhexlify(d["hmac"]) == hmac_entropy_encrypted and entropy == entropy_decrypt(entropy_encrypted):
gui.alert("Success!", "Your encrypted key is saved in the memory now")
else:
gui.error("Something went wrong")
except Exception as e:
gui.error("Fail: %r" % e)
def gen_mnemonic(num_words: int) -> str:
"""Generates a mnemonic with num_words"""
if num_words < 12 or num_words > 24 or num_words % 3 != 0:
raise RuntimeError("Invalid word count")
return bip39.mnemonic_from_bytes(rng.get_random_bytes(num_words * 4 // 3))
def sign(self, tx):
# good practice to randomize context
# it reduces chances of side-channel attacks
secp256k1.context_randomize(get_random_bytes(32))
tx.sign_with(self.root)
return tx
def open(self, mode=None):
"""Opens a secure channel.
Mode can be "es" - ephemeral-static
or "ee" - ephemeral-ephemenral
"""
# save mode for later - i.e. reestablish secure channel
if mode is None:
mode = self.mode
else:
self.mode = mode
# check if we know pubkey already
if self.card_pubkey is None:
self.get_card_pubkey()
# generate ephimerial key
secret = get_random_bytes(32)
host_prv = secret
host_pub = secp256k1.ec_pubkey_create(secret)
# ee mode - ask card to create ephimerial key and send it to us
if mode == "ee":
data = secp256k1.ec_pubkey_serialize(host_pub,
secp256k1.EC_UNCOMPRESSED)
# get ephimerial pubkey from the card
res = self.applet.request(self.OPEN_EE + encode(data))
s = BytesIO(res)
data = s.read(65)
pub = secp256k1.ec_pubkey_parse(data)
secp256k1.ec_pubkey_tweak_mul(pub, secret)
shared_secret = hashlib.sha256(
secp256k1.ec_pubkey_serialize(pub)[1:33]).digest()
shared_fingerprint = self.derive_keys(shared_secret)
recv_hmac = s.read(MAC_SIZE)
h = hmac.new(self.card_mac_key, digestmod="sha256")
h.update(data)
expected_hmac = h.digest()[:MAC_SIZE]
if expected_hmac != recv_hmac:
raise SecureChannelError("Wrong HMAC.")
data += recv_hmac
raw_sig = s.read()
sig = secp256k1.ecdsa_signature_parse_der(raw_sig)
# in case card doesn't follow low s rule (but it should)
sig = secp256k1.ecdsa_signature_normalize(sig)
if not secp256k1.ecdsa_verify(sig,
hashlib.sha256(data).digest(),
self.card_pubkey):
raise SecureChannelError("Signature is invalid.")
# se mode - use our ephimerial key with card's static key
else:
data = secp256k1.ec_pubkey_serialize(host_pub,
secp256k1.EC_UNCOMPRESSED)
# ugly copy
pub = secp256k1.ec_pubkey_parse(
secp256k1.ec_pubkey_serialize(self.card_pubkey))
secp256k1.ec_pubkey_tweak_mul(pub, secret)
shared_secret = secp256k1.ec_pubkey_serialize(pub)[1:33]
res = self.applet.request(self.OPEN_SE + encode(data))
s = BytesIO(res)
nonce_card = s.read(32)
recv_hmac = s.read(MAC_SIZE)
secret_with_nonces = hashlib.sha256(shared_secret +
nonce_card).digest()
shared_fingerprint = self.derive_keys(secret_with_nonces)
data = nonce_card
h = hmac.new(self.card_mac_key, digestmod="sha256")
h.update(data)
expected_hmac = h.digest()[:MAC_SIZE]
if expected_hmac != recv_hmac:
raise SecureChannelError("Wrong HMAC.")
data += recv_hmac
sig = secp256k1.ecdsa_signature_parse_der(s.read())
# in case card doesn't follow low s rule (but it should)
sig = secp256k1.ecdsa_signature_normalize(sig)
if not secp256k1.ecdsa_verify(sig,
hashlib.sha256(data).digest(),
self.card_pubkey):
raise SecureChannelError("Signature is invalid")
# reset iv
self.iv = 0
self.is_open = True
def get_new_mnemonic(words=12):
entropy_len = words*4//3
global entropy
entropy = get_random_bytes(entropy_len)
return bip39.mnemonic_from_bytes(entropy)
def ask_pin(first_time_usage, callback):
scr = switch_to_new_screen()
first_time_title = "Choose a PIN code"
title = "Enter your PIN code"
if first_time_usage:
title = first_time_title
title_lbl = add_label(title, y=PADDING, style="title")
btnm = lv.btnm(scr)
# shuffle numbers to make sure
# no constant fingerprints left on screen
buttons = ["%d" % i for i in range(0,10)]
btnmap = []
for j in range(3):
for i in range(3):
v = rng.get_random_bytes(1)[0] % len(buttons)
btnmap.append(buttons.pop(v))
btnmap.append("\n")
btnmap = btnmap+[lv.SYMBOL.CLOSE, buttons.pop(), lv.SYMBOL.OK, ""]
btnm.set_map(btnmap)
btnm.set_width(HOR_RES)
btnm.set_height(HOR_RES)
btnm.align(scr, lv.ALIGN.IN_BOTTOM_MID, 0, 0)
# remove feedback on press to avoid sidechannels
btnm.set_style(lv.btnm.STYLE.BTN_PR,btnm.get_style(lv.btnm.STYLE.BTN_REL))
pin_lbl = lv.ta(scr)
pin_lbl.set_text("")
pin_lbl.set_pwd_mode(True)
style = lv.style_t()
lv.style_copy(style, styles["theme"].style.ta.oneline)
style.text.font = lv.font_roboto_28
style.text.color = lv.color_hex(0xffffff)
style.text.letter_space = 15
pin_lbl.set_style(lv.label.STYLE.MAIN, style)
pin_lbl.set_width(HOR_RES-2*PADDING)
pin_lbl.set_x(PADDING)
pin_lbl.set_y(PADDING+50)
pin_lbl.set_cursor_type(lv.CURSOR.HIDDEN)
pin_lbl.set_one_line(True)
pin_lbl.set_text_align(lv.label.ALIGN.CENTER)
pin_lbl.set_pwd_show_time(0)
instruct_txt = "Device tamper check.\nThese words should remain #ffffff the same every time#:"
instruct_label = add_label(instruct_txt, 180, style="hint")
instruct_label.set_recolor(True)
antiphish_label = add_label(antiphishing_word(""), 250)
Pin.read_counter()
@feed_rng
def cb(obj, event):
nonlocal first_time_usage
if event == lv.EVENT.RELEASED:
c = obj.get_active_btn_text()
if c is None:
return
if c == lv.SYMBOL.CLOSE:
pin_lbl.set_text("")
antiphish_label.set_text(antiphishing_word(""))
elif c == lv.SYMBOL.OK:
# FIXME: check PIN len
Key.generate_key(pin_lbl.get_text());
if first_time_usage:
Secret.save_secret(alert);
callback()
else:
Pin.counter -= 1
Pin.save_counter(alert)
if Pin.is_pin_valid():
Pin.reset_counter(alert)
callback()
else:
instruct_label.set_text("#f07070 Wrong pin: %d/%d #" % (Pin.counter, Pin.ATTEMPTS_MAX))
if Pin.counter <= 0:
Factory_settings.restore(alert)
Secret.generate_secret()
alert("Security","Device has been factory reset!")
first_time_usage = True
title_lbl.set_text(first_time_title)
instruct_label.set_text(instruct_txt)
pin_lbl.set_text("")
antiphish_label.set_text(antiphishing_word(""))
else:
instruct_label.set_text(instruct_txt)
pin_lbl.add_text(c)
word = antiphishing_word(pin_lbl.get_text())
antiphish_label.set_text(antiphish_label.get_text() + " " + word)
btnm.set_event_cb(cb);
def generate_secret():
Secret.secret = get_random_bytes(32)
def roll_dice(sides=6):
""" return 1 ... sides """
d = get_random_bytes(1)
print (sides)
print (d)
return 1+int.from_bytes(d, 'big') % sides
