def create_pairing_response_by_serial(self, user_token_id):
"""
Creates a base64-encoded pairing response that identifies
the token by its serial
:param user_token_id: the token id (primary key for the user token db)
:returns base64 encoded pairing response
"""
token_serial = self.tokens[user_token_id]['serial']
server_public_key = self.tokens[user_token_id]['server_public_key']
partition = self.tokens[user_token_id]['partition']
# ------------------------------------------------------------------- --
# assemble header and plaintext
header = struct.pack('<bI', PAIR_RESPONSE_VERSION, partition)
pairing_response = b''
pairing_response += struct.pack('<bI', TYPE_PUSHTOKEN, user_token_id)
pairing_response += self.public_key
pairing_response += token_serial.encode('utf8') + b'\x00\x00'
pairing_response += self.gda + b'\x00'
signature = crypto_sign_detached(pairing_response, self.secret_key)
pairing_response += signature
# ------------------------------------------------------------------- --
# create public diffie hellman component
# (used to decrypt and verify the reponse)
r = os.urandom(32)
R = calc_dh_base(r)
# ------------------------------------------------------------------- --
# derive encryption key and nonce
server_public_key_dh = dsa_to_dh_public(server_public_key)
ss = calc_dh(r, server_public_key_dh)
U = SHA256.new(ss).digest()
encryption_key = U[0:16]
nonce = U[16:32]
# ------------------------------------------------------------------- --
# encrypt in EAX mode
cipher = AES.new(encryption_key, AES.MODE_EAX, nonce)
cipher.update(header)
ciphertext, tag = cipher.encrypt_and_digest(pairing_response)
return encode_base64_urlsafe(header + R + ciphertext + tag)
def test_failed_signreq(self):
""" PushToken: Check if signing transactions fails correctly """
user_token_id = self.execute_correct_pairing()
challenge_url = self.trigger_challenge(user_token_id, data='Yes, I '
'want to know why doctors hate this guy. Take these 6000 $ with '
'all my sincere benevolence and send me the black magic diet pill '
'they don\'t want me to know about',
content_type=CONTENT_TYPE_SIGNREQ)
challenge, __ = self.decrypt_and_verify_challenge(challenge_url)
wrong_sig = encode_base64_urlsafe('DEADBEEF' * 32)
# ------------------------------------------------------------------- --
# check if the content type is right
content_type = challenge['content_type']
self.assertEqual(content_type, CONTENT_TYPE_SIGNREQ)
# ------------------------------------------------------------------- --
# prepare params for validate
params = {'transactionid': challenge['transaction_id'],
'pass': wrong_sig}
# again, we ignore the callback definitions
response = self.make_validate_request('check_t', params)
response_dict = json.loads(response.body)
self.assertIn('status', response_dict.get('result', {}))
status = response_dict.get('result', {}).get('status')
value = response_dict.get('result', {}).get('value')
self.assertTrue(status)
value = response_dict.get('result', {}).get('value')
self.assertIn('value', value)
self.assertIn('failcount', value)
value_value = value.get('value')
failcount = value.get('failcount')
self.assertFalse(value_value)
self.assertGreater(failcount, 0)
def generate_pairing_url(token_type,
server_public_key,
serial=None,
callback_url=None,
callback_sms_number=None,
otp_pin_length=None,
hash_algorithm=None):
"""
Generates a pairing url that should be sent to the client.
Mandatory parameters:
:param: token_type The token type for which this url is generated
as a string (currently supported is only 'qr')
:param: server_public_key: The servers public key as bytes (length: 32)
Optional parameters:
:param serial: When a token for the client was already enrolled
(e.g. manually in the manage interface) its serial has to be
sent to the client. When serial is not specified the client will
receive a so-called 'anonymous pairing url' with no token data
inside it. The token will then be created after the server
received a pairing response from the client.
:param callback_url: A callback URL that should be used by the client
to sent back the pairing reponse. Please note, that this url will
be cached by the client and used in the challenge step, if the
challenge doesn't provide a custom url
:param callback_sms_number: A sms number that can be used by the client
to send back the pairing response. Typically this is used as a
fallback for offline pairing.
As with the callback url please note, that the number will be
cached by the client. If you want a different number in the
challenge step you have to send it inside the challenge as
specified in the challenge protocol
:param otp_pin_length: The number of digits the otp has to consist of.
:param hash_algorithm: A string value that signifies the hash algorithm
used in calculating the hmac. Currently the values 'sha1', 'sha256',
'sha512' are supported. If the parameter is left out the default
depends on the token type. qrtoken uses sha256 as default, while
hotp/totp uses sha1.
The function can raise several exceptions:
:raises InvalidFunctionParameter: If the string given in token_type
doesn't match a supported token type
:raises InvalidFunctionParameter: If the string given in hash_algorithm
doesn't match a supported hash algorithm
:raises InvalidFunctionParameter: If public key has a different size
than 32 bytes
:raises InvalidFunctionParameter: If otp_pin_length value is not between
1 and 127
:return: Pairing URL string
"""
# --------------------------------------------------------------------------
# check the token type
try:
TOKEN_TYPE = token_types[token_type]
except KeyError:
allowed_types = ', '.join(token_types.keys())
raise InvalidFunctionParameter('token_type',
'Unsupported token type %s. Supported '
'types for pairing are: %s' %
(token_type, allowed_types))
# --------------------------------------------------------------------------
# initialize the flag bitmap
flags = 0
if serial is not None:
flags |= FLAG_PAIR_SERIAL
if callback_url is not None:
flags |= FLAG_PAIR_CBURL
if callback_sms_number is not None:
flags |= FLAG_PAIR_CBSMS
if hash_algorithm is not None:
flags |= FLAG_PAIR_HMAC
if otp_pin_length is not None:
flags |= FLAG_PAIR_DIGITS
# --------------------------------------------------------------------------
# ------------------------------
# fields | version | type | flags | ... |
# ------------------------------
# size | 1 | 1 | 4 | ? |
# ------------------------------
data = struct.pack('<bbI', PAIR_VERSION, TOKEN_TYPE, flags)
# --------------------------------------------------------------------------
# -------------------------------
# fields | ... | server public key | ... |
# -------------------------------
# size | 6 | 32 | ? |
# -------------------------------
if len(server_public_key) != 32:
raise InvalidFunctionParameter('server_public_key', 'Public key must '
'be 32 bytes long')
data += server_public_key
# --------------------------------------------------------------------------
# Depending on flags additional data may be sent. If serial was provided
# serial will be sent back. If callback url or callback sms was provided
# the corresponding data will be added, too
# --------------------------------------------------------
# fields | ... | serial | NUL | cb url | NUL | cb sms | NUL | ... |
# --------------------------------------------------------
# size | 38 | ? | 1 | ? | 1 | ? | 1 | ? |
# --------------------------------------------------------
if flags & FLAG_PAIR_SERIAL:
data += serial.encode('utf8') + b'\x00'
if flags & FLAG_PAIR_CBURL:
data += callback_url.encode('utf8') + b'\x00'
if flags & FLAG_PAIR_CBSMS:
data += callback_sms_number.encode('utf8') + b'\x00'
# --------------------------------------------------------------------------
# Other optional values: allowed pin length of otp (number of digits)
# and custom hash algorithm
# ---------------------------------------
# fields | ... | otp pin length | hash_algorithm |
# ---------------------------------------
# size | ? | 1 | 1 |
# ---------------------------------------
if flags & FLAG_PAIR_DIGITS:
if not(6 <= otp_pin_length <= 12):
raise InvalidFunctionParameter('otp_pin_length', 'Pin length must '
'be in the range 6..12')
data += struct.pack('<b', otp_pin_length)
if flags & FLAG_PAIR_HMAC:
try:
HASH_ALGO = hash_algorithms[hash_algorithm]
except KeyError:
allowed_values = ", ".join(hash_algorithms.keys())
raise InvalidFunctionParameter('Unsupported hash algorithm %s, '
'allowed values are %s' %
(hash_algorithm, allowed_values))
data += struct.pack('<b', HASH_ALGO)
# --------------------------------------------------------------------------
# TODO missing token details for other protocols (hotp, hmac, etc)
# * counter (u64le)
# * tstart (u64le)
# * tstep (u32le)
# TODO: replace lseqr literal with global config value
# or global constant
return 'lseqr://pair/' + encode_base64_urlsafe(data)
def create_challenge_url(self,
transaction_id,
content_type,
callback_url='',
message=None,
login=None,
host=None):
"""
creates a challenge url (looking like lseqr://push/<base64string>),
returns the url and the unencrypted challenge data
:param transaction_id: The transaction id generated by LinOTP
:param content_type: One of the types CONTENT_TYPE_SIGNREQ,
CONTENT_TYPE_PAIRING, CONTENT_TYPE_LOGIN
:param callback_url: callback url (optional), default is
empty string
:param message: the transaction message, that should be signed
by the client. Only for content type CONTENT_TYPE_SIGNREQ
:param login: the login name of the user. Only for content type
CONTENT_TYPE_LOGIN
:param host: hostname of the user. Only for content type
CONTENT_TYPE_LOGIN
:returns: tuple (challenge_url, challenge_data), with challenge_url
being the push url and challenge data being the data, that
will be used as message in the signing step.
"""
serial = self.getSerial()
# ----------------------------------------------------------------------
# sanity/format checks
if content_type not in [CONTENT_TYPE_SIGNREQ,
CONTENT_TYPE_PAIRING, CONTENT_TYPE_LOGIN]:
raise InvalidFunctionParameter('content_type', 'content_type must '
'be CONTENT_TYPE_SIGNREQ, '
'CONTENT_TYPE_PAIRING or '
'CONTENT_TYPE_LOGIN.')
# ----------------------------------------------------------------------
# after the lseqr://push/ prefix the following data is encoded
# in urlsafe base64:
# ---------------------------------------------------
# fields | version | user token id | R | ciphertext | sign |
# ---------------------------------------------------
# | header | body |
# ---------------------------------------------------
# size | 1 | 4 | 32 | ? | 64 |
# ---------------------------------------------------
#
# create header
user_token_id = self.getFromTokenInfo('user_token_id')
data_header = struct.pack('<bI', CHALLENGE_URL_VERSION, user_token_id)
# ----------------------------------------------------------------------
# create body
r = urandom(32)
R = calc_dh_base(r)
b64_user_dsa_public_key = self.getFromTokenInfo('user_dsa_public_key')
user_dsa_public_key = b64decode(b64_user_dsa_public_key)
user_dh_public_key = dsa_to_dh_public(user_dsa_public_key)
ss = calc_dh(r, user_dh_public_key)
U = SHA256.new(ss).digest()
zerome(ss)
sk = U[0:16]
nonce = U[16:32]
zerome(U)
# ----------------------------------------------------------------------
# create plaintext section
# ----------------------------------------------------------------------
# generate plaintext header
# --------------------------------------
# fields | content_type | transaction_id | ... |
# --------------------------------------
# size | 1 | 8 | ? |
# --------------------------------------
transaction_id = transaction_id_to_u64(transaction_id)
pt_header = struct.pack('<bQ', content_type, transaction_id)
plaintext = pt_header
# ----------------------------------------------------------------------
utf8_callback_url = callback_url.encode('utf8')
# enforce max url length as specified in protocol
if len(utf8_callback_url) > 511:
raise InvalidFunctionParameter('callback_url', 'max string '
'length (encoded as utf8) is '
'511')
# ----------------------------------------------------------------------
# create data package depending on content type
# ----------------------------------------------------------------------
if content_type == CONTENT_TYPE_PAIRING:
# -----------------------------------------
# fields | header | serial | NUL | callback | NUL |
# -----------------------------------------
# size | 9 | ? | 1 | ? | 1 |
# -----------------------------------------
utf8_serial = serial.encode('utf8')
if len(utf8_serial) > 63:
raise ValueError('serial (encoded as utf8) can only be 63 '
'characters long')
plaintext += utf8_serial + b'\00' + utf8_callback_url + b'\00'
# ----------------------------------------------------------------------
if content_type == CONTENT_TYPE_SIGNREQ:
if message is None:
raise InvalidFunctionParameter('message', 'message must be '
'supplied for content type '
'SIGNREQ')
# ------------------------------------------
# fields | header | message | NUL | callback | NUL |
# ------------------------------------------
# size | 9 | ? | 1 | ? | 1 |
# ------------------------------------------
utf8_message = message.encode('utf8')
# enforce max sizes specified by protocol
if len(utf8_message) > 511:
raise InvalidFunctionParameter('message', 'max string '
'length (encoded as utf8) is '
'511')
plaintext += utf8_message + b'\00' + utf8_callback_url + b'\00'
# ----------------------------------------------------------------------
if content_type == CONTENT_TYPE_LOGIN:
if login is None:
raise InvalidFunctionParameter('login', 'login must be '
'supplied for content type '
'LOGIN')
if host is None:
raise InvalidFunctionParameter('host', 'host must be '
'supplied for content type '
'LOGIN')
# -----------------------------------------------------
# fields | header | login | NUL | host | NUL | callback | NUL |
# -----------------------------------------------------
# size | 9 | ? | 1 | ? | 1 | ? | 1 |
# -----------------------------------------------------
utf8_login = login.encode('utf8')
utf8_host = host.encode('utf8')
# enforce max sizes specified by protocol
if len(utf8_login) > 127:
raise InvalidFunctionParameter('login', 'max string '
'length (encoded as utf8) is '
'127')
if len(utf8_host) > 255:
raise InvalidFunctionParameter('host', 'max string '
'length (encoded as utf8) is '
'255')
plaintext += utf8_login + b'\00'
plaintext += utf8_host + b'\00'
plaintext += utf8_callback_url + b'\00'
# ----------------------------------------------------------------------
# encrypt inner layer
nonce_as_int = int_from_bytes(nonce, byteorder='big')
ctr = Counter.new(128, initial_value=nonce_as_int)
cipher = AES.new(sk, AES.MODE_CTR, counter=ctr)
ciphertext = cipher.encrypt(plaintext)
unsigned_raw_data = data_header + R + ciphertext
# ----------------------------------------------------------------------
# create signature
partition = self.getFromTokenInfo('partition')
secret_key = get_secret_key(partition)
signature = crypto_sign_detached(unsigned_raw_data, secret_key)
raw_data = unsigned_raw_data + signature
url = 'lseqr://push/' + encode_base64_urlsafe(raw_data)
return url, plaintext
def generate_pairing_url(token_type,
partition=None,
serial=None,
callback_url=None,
callback_sms_number=None,
otp_pin_length=None,
hash_algorithm=None,
use_cert=False):
"""
Generates a pairing url that should be sent to the client.
Mandatory parameters:
:param: token_type The token type for which this url is generated
as a string (currently supported is only 'qr')
Optional parameters:
:param partition: A partition id that should be used during pairing.
Partitions identitify a subspace of tokens, that share a common
key pair. This currently defaults to the enum id of the token
type when set to None and is reserved for future use.
:param serial: When a token for the client was already enrolled
(e.g. manually in the manage interface) its serial has to be
sent to the client. When serial is not specified the client will
receive a so-called 'anonymous pairing url' with no token data
inside it. The token will then be created after the server
received a pairing response from the client.
:param callback_url: A callback URL that should be used by the client
to sent back the pairing reponse. Please note, that this url will
be cached by the client and used in the challenge step, if the
challenge doesn't provide a custom url
:param callback_sms_number: A sms number that can be used by the client
to send back the pairing response. Typically this is used as a
fallback for offline pairing.
As with the callback url please note, that the number will be
cached by the client. If you want a different number in the
challenge step you have to send it inside the challenge as
specified in the challenge protocol
:param otp_pin_length: The number of digits the otp has to consist of.
:param hash_algorithm: A string value that signifies the hash algorithm
used in calculating the hmac. Currently the values 'sha1', 'sha256',
'sha512' are supported. If the parameter is left out the default
depends on the token type. qrtoken uses sha256 as default, while
hotp/totp uses sha1.
:param use_cert: A boolean, if a server certificate should be used
in the pairing url
The function can raise several exceptions:
:raises InvalidFunctionParameter: If the string given in token_type
doesn't match a supported token type
:raises InvalidFunctionParameter: If the string given in hash_algorithm
doesn't match a supported hash algorithm
:raises InvalidFunctionParameter: If public key has a different size
than 32 bytes
:raises InvalidFunctionParameter: If otp_pin_length value is not between
1 and 127
:return: Pairing URL string
"""
# ----------------------------------------------------------------------- --
# check the token type
try:
TOKEN_TYPE = TOKEN_TYPES[token_type]
except KeyError:
allowed_types = ', '.join(TOKEN_TYPES.keys())
raise InvalidFunctionParameter(
'token_type', 'Unsupported token type %s. Supported '
'types for pairing are: %s' % (token_type, allowed_types))
# ----------------------------------------------------------------------- --
# initialize the flag bitmap
flags = 0
if not use_cert:
flags |= FLAG_PAIR_PK
if serial is not None:
flags |= FLAG_PAIR_SERIAL
if callback_url is not None:
flags |= FLAG_PAIR_CBURL
if callback_sms_number is not None:
flags |= FLAG_PAIR_CBSMS
if hash_algorithm is not None:
flags |= FLAG_PAIR_HMAC
if otp_pin_length is not None:
flags |= FLAG_PAIR_DIGITS
# ----------------------------------------------------------------------- --
# ------------------------------
# fields | version | type | flags | ... |
# ------------------------------
# size | 1 | 1 | 4 | ? |
# ------------------------------
data = struct.pack('<bbI', PAIR_URL_VERSION, TOKEN_TYPE, flags)
# ----------------------------------------------------------------------- --
# -----------------------
# fields | ... | partition | ... |
# -----------------------
# size | 6 | 4 | ? |
# -----------------------
data += struct.pack('<I', partition)
# ----------------------------------------------------------------------- --
# --------------------------------
# fields | .... | server public key | ... |
# --------------------------------
# size | 10 | 32 | ? |
# --------------------------------
if flags & FLAG_PAIR_PK:
server_public_key = get_public_key(partition)
if len(server_public_key) != 32:
raise InvalidFunctionParameter('server_public_key',
'Public key must be 32 bytes long')
data += server_public_key
# ----------------------------------------------------------------------- --
# Depending on flags additional data may be sent. If serial was provided
# serial will be sent back. If callback url or callback sms was provided
# the corresponding data will be added, too
# --------------------------------------------------------
# fields | .... | serial | NUL | cb url | NUL | cb sms | NUL | ... |
# --------------------------------------------------------
# size | 42 | ? | 1 | ? | 1 | ? | 1 | ? |
# --------------------------------------------------------
if flags & FLAG_PAIR_SERIAL:
data += serial.encode('utf8') + b'\x00'
if flags & FLAG_PAIR_CBURL:
data += callback_url.encode('utf8') + b'\x00'
if flags & FLAG_PAIR_CBSMS:
data += callback_sms_number.encode('utf8') + b'\x00'
# ----------------------------------------------------------------------- --
# Other optional values: allowed pin length of otp (number of digits)
# and custom hash algorithm
# ---------------------------------------
# fields | ... | otp pin length | hash_algorithm |
# ---------------------------------------
# size | ? | 1 | 1 |
# ---------------------------------------
if flags & FLAG_PAIR_DIGITS:
if not (6 <= otp_pin_length <= 12):
raise InvalidFunctionParameter(
'otp_pin_length', 'Pin length must '
'be in the range 6..12')
data += struct.pack('<b', otp_pin_length)
if flags & FLAG_PAIR_HMAC:
try:
HASH_ALGO = hash_algorithms[hash_algorithm]
except KeyError:
allowed_values = ", ".join(hash_algorithms.keys())
raise InvalidFunctionParameter(
'hash_algorithm', 'Unsupported hash algorithm %s, '
'allowed values are %s' % (hash_algorithm, allowed_values))
data += struct.pack('<b', HASH_ALGO)
# ----------------------------------------------------------------------- --
# TODO missing token details for other protocols (hotp, hmac, etc)
# * counter (u64le)
# * tstart (u64le)
# * tstep (u32le)
# TODO: replace lseqr literal with global config value
# or global constant
if not (flags & FLAG_PAIR_PK):
secret_key = get_secret_key(partition)
server_sig = crypto_sign_detached(data, secret_key)
data += server_sig
return 'lseqr://pair/' + encode_base64_urlsafe(data)
def create_challenge_url(self, transaction_id, content_type, message,
callback_url, callback_sms_number,
use_compression=False, reset_url=False):
"""
creates a challenge url (looking like lseqr://chal/<base64string>)
from a challenge dictionary as provided by Challanges.create_challenge
in lib.challenge
the version identifier of the challenge url is currently hardcoded
to 1.
"""
serial = self.getSerial()
if content_type is None:
content_type = CONTENT_TYPE_FREE
# ----------------------------------------------------------------------
# sanity/format checks
if content_type not in [CONTENT_TYPE_PAIRING,
CONTENT_TYPE_AUTH, CONTENT_TYPE_FREE]:
raise InvalidFunctionParameter('content_type', 'content_type must '
'be CONTENT_TYPE_PAIRING, '
'CONTENT_TYPE_AUTH or '
'CONTENT_TYPE_FREE.')
if content_type == CONTENT_TYPE_PAIRING and \
message != serial:
raise InvalidFunctionParameter('message', 'message must be equal '
'to serial in pairing mode')
if content_type == CONTENT_TYPE_AUTH:
if '@' not in message:
raise InvalidFunctionParameter('message', 'For content type '
'auth, message must have format '
'<login>@<server>')
# ----------------------------------------------------------------------
# after the lseqr://chal/ prefix the following data is encoded
# in urlsafe base64:
# ---------------------------------------------------
# fields | version | user token id | R | ciphertext | MAC |
# ---------------------------------------------------
# | header | | EAX enc data |
# ---------------------------------------------------
# size | 1 | 4 | 32 | ? | 16 |
# ---------------------------------------------------
#
r = urandom(32)
R = calc_dh_base(r)
user_token_id = self.getFromTokenInfo('user_token_id')
data_header = struct.pack('<bI', QRTOKEN_VERSION, user_token_id)
# the user public key is saved as base64 in
# the token info since the byte format is
# incompatible with the json backend.
b64_user_public_key = self.getFromTokenInfo('user_public_key')
user_public_key = b64decode(b64_user_public_key)
ss = calc_dh(r, user_public_key)
U1 = SHA256.new(ss).digest()
U2 = SHA256.new(U1).digest()
zerome(ss)
skA = U1[0:16]
skB = U2[0:16]
nonce = U2[16:32]
zerome(U1)
zerome(U2)
# ----------------------------------------------------------------------
# create plaintext section
# ----------------------------------------------------------------------
# create the bitmap for flags
flags = 0
if use_compression:
flags |= CHALLENGE_HAS_COMPRESSION
# FIXME: sizecheck for message, callback url, sms number
# wiki specs are utf-8 byte length (without \0)
if callback_url is not None:
flags |= CHALLENGE_HAS_URL
if callback_sms_number is not None:
flags |= CHALLENGE_HAS_SMS_NUMBER
if (content_type == CONTENT_TYPE_PAIRING):
flags |= CHALLENGE_HAS_SIGNATURE
if reset_url:
flags |= CHALLENGE_SHOULD_RESET_URL
flags |= CHALLENGE_HAS_SIGNATURE
#----------------------------------------------------------------------
# generate plaintext header
# ----------------------------------------------
# fields | content_type | flags | transaction_id | ... |
# ----------------------------------------------
# size | 1 | 1 | 8 | ? |
# ----------------------------------------------
transaction_id = transaction_id_to_u64(transaction_id)
pt_header = struct.pack('<bbQ', content_type, flags, transaction_id)
plaintext = pt_header
#----------------------------------------------------------------------
# create data package
# -------------------------------
# fields | header | message | NUL | ... |
# -------------------------------
# size | 10 | ? | 1 | ? |
# -------------------------------
data_package = b''
utf8_message = message.encode('utf8')
# enforce max sizes specified by protocol
if content_type == CONTENT_TYPE_FREE and len(utf8_message) > 511:
raise ParameterError('message (encoded as utf8) can only be 511 '
'characters long')
elif content_type == CONTENT_TYPE_PAIRING and len(utf8_message) > 63:
raise InvalidFunctionParameter('message', 'max string length '
'(encoded as utf8) is 511 for '
'content type PAIRING')
elif content_type == CONTENT_TYPE_AUTH and len(utf8_message) > 511:
raise InvalidFunctionParameter('message', 'max string length '
'(encoded as utf8) is 511 for '
'content type AUTH')
data_package += utf8_message + b'\x00'
# ----------------------------------------------------------------------
# depending on function parameters add callback url
# and/or callback sms number
# -----------------------------------------------------
# fields | ... | callback url | NUL | callback sms | NUL | ... |
# -----------------------------------------------------
# size | ? | ? | 1 | ? | 1 | ? |
# -----------------------------------------------------
# ----------------------------------------------------------------------
if callback_url is not None:
utf8_callback_url = callback_url.encode('utf8')
# enforce max url length as specified in protocol
if len(utf8_callback_url) > 511:
raise InvalidFunctionParameter('callback_url', 'max string '
'length (encoded as utf8) is '
'511')
data_package += utf8_callback_url + b'\x00'
# ----------------------------------------------------------------------
if callback_sms_number is not None:
utf8_callback_sms_number = callback_sms_number.encode('utf8')
if len(utf8_callback_sms_number) > 31:
raise InvalidFunctionParameter('callback_sms_number',
'max string length (encoded '
'as utf8) is 31')
data_package += utf8_callback_sms_number + b'\x00'
# ----------------------------------------------------------------------
if use_compression:
maybe_compressed_data_package = zlib.compress(data_package, 9)
else:
maybe_compressed_data_package = data_package
# ----------------------------------------------------------------------
# when content type is pairing the protocol specifies that
# the server must send a hmac based signature with the
# response
sig = ''
if flags & CHALLENGE_HAS_SIGNATURE:
hmac_message = nonce + pt_header + maybe_compressed_data_package
sig = HMAC.new(self.server_hmac_secret, hmac_message,
digestmod=SHA256).digest()
plaintext += sig
# ----------------------------------------------------------------------
plaintext += maybe_compressed_data_package
# ----------------------------------------------------------------------
user_message = nonce + pt_header + sig + data_package
user_sig = HMAC.new(skB, user_message, digestmod=SHA256).digest()
# the user sig will be given as urlsafe base64 in the
# challenge response. for this reasons (and because we
# need to serialize it into json) we convert the user_sig
# into this format.
user_sig = encode_base64_urlsafe(user_sig)
# ----------------------------------------------------------------------
cipher = AES.new(skA, AES.MODE_EAX, nonce)
cipher.update(data_header)
ciphertext, tag = cipher.encrypt_and_digest(plaintext)
raw_data = data_header + R + ciphertext + tag
url = 'lseqr://chal/' + encode_base64_urlsafe(raw_data)
return url, user_sig
def decrypt_and_verify_challenge(self, challenge_url):
"""
Decrypts the data packed in the challenge url, verifies
its content, returns the parsed data as a dictionary,
calculates and returns the signature.
The calling method must then send the signature
back to the server. (The reason for this control flow
is that the challenge data must be checked in different
scenarios, e.g. when we have a pairing the data must be
checked by the method that simulates the pairing)
:param challenge_url: the challenge url as sent by the server
:returns: (challenge, signature)
challenge has the keys
* content_type - one of the three values CONTENT_TYPE_SIGNREQ,
CONTENT_TYPE_PAIRING or CONTENT_TYPE_LOGIN)
(all defined in this module)
* transaction_id - used to identify the challenge
on the server
* callback_url (optional) - the url to which the challenge
response should be set
* user_token_id - used to identify the token in the
user database for which this challenge was created
depending on the content type additional keys are present
* for CONTENT_TYPE_PAIRING: serial
* for CONTENT_TYPE_SIGNREQ: message
* for CONTENT_TYPE_LOGIN: login, host
signature is the generated user signature used to
respond to the challenge
"""
challenge_data_encoded = challenge_url[len('lseqr://chal/'):]
challenge_data = decode_base64_urlsafe(challenge_data_encoded)
# ------------------------------------------------------------------- --
# parse and verify header information in the
# encrypted challenge data
header = challenge_data[0:5]
version, user_token_id = struct.unpack('<bI', header)
self.assertEqual(version, CHALLENGE_URL_VERSION)
# ------------------------------------------------------------------- --
# get token from client token database
token = self.tokens[user_token_id]
server_public_key = token['server_public_key']
# ------------------------------------------------------------------- --
# prepare decryption by seperating R from
# ciphertext and server signature
R = challenge_data[5:5 + 32]
ciphertext = challenge_data[5 + 32:-64]
server_signature = challenge_data[-64:]
# check signature
data = challenge_data[0:-64]
crypto_sign_verify_detached(server_signature, data, server_public_key)
# ------------------------------------------------------------------- --
# key derivation
secret_key_dh = dsa_to_dh_secret(self.secret_key)
ss = calc_dh(secret_key_dh, R)
U = SHA256.new(ss).digest()
sk = U[0:16]
nonce = U[16:32]
# ------------------------------------------------------------------- --
# decrypt and verify challenge
nonce_as_int = int_from_bytes(nonce, byteorder='big')
ctr = Counter.new(128, initial_value=nonce_as_int)
cipher = AES.new(sk, AES.MODE_CTR, counter=ctr)
plaintext = cipher.decrypt(ciphertext)
# ------------------------------------------------------------------- --
# parse/check plaintext header
pt_header = plaintext[0:9]
content_type, transaction_id = struct.unpack('<bQ', pt_header)
transaction_id = u64_to_transaction_id(transaction_id)
# ------------------------------------------------------------------- --
# prepare the parsed challenge data
challenge = {}
challenge['content_type'] = content_type
# ------------------------------------------------------------------- --
# retrieve plaintext data depending on content_type
if content_type == CONTENT_TYPE_PAIRING:
serial, callback_url, __ = plaintext[9:].split('\x00')
challenge['serial'] = serial
elif content_type == CONTENT_TYPE_SIGNREQ:
message, callback_url, __ = plaintext[9:].split('\x00')
challenge['message'] = message
elif content_type == CONTENT_TYPE_LOGIN:
login, host, callback_url, __ = plaintext[9:].split('\x00')
challenge['login'] = login
challenge['host'] = host
# ------------------------------------------------------------------- --
# prepare the parsed challenge data
challenge['callback_url'] = callback_url
challenge['transaction_id'] = transaction_id
challenge['user_token_id'] = user_token_id
# calculate signature
sig_base = server_signature + plaintext
sig = crypto_sign_detached(sig_base, self.secret_key)
encoded_sig = encode_base64_urlsafe(sig)
return challenge, encoded_sig
def create_challenge_url(self, transaction_id, content_type, message,
callback_url, callback_sms_number,
use_compression=False, reset_url=False):
"""
creates a challenge url (looking like lseqr://chal/<base64string>)
from a challenge dictionary as provided by Challanges.create_challenge
in lib.challenge
the version identifier of the challenge url is currently hardcoded
to 1.
"""
serial = self.getSerial()
if content_type is None:
content_type = CONTENT_TYPE_FREE
# ------------------------------------------------------------------- --
# sanity/format checks
if content_type not in [CONTENT_TYPE_PAIRING,
CONTENT_TYPE_AUTH, CONTENT_TYPE_FREE]:
raise InvalidFunctionParameter('content_type', 'content_type must '
'be CONTENT_TYPE_PAIRING, '
'CONTENT_TYPE_AUTH or '
'CONTENT_TYPE_FREE.')
if content_type == CONTENT_TYPE_PAIRING and \
message != serial:
raise InvalidFunctionParameter('message', 'message must be equal '
'to serial in pairing mode')
if content_type == CONTENT_TYPE_AUTH:
if '@' not in message:
raise InvalidFunctionParameter('message', 'For content type '
'auth, message must have format '
'<login>@<server>')
# ------------------------------------------------------------------- --
# after the lseqr://chal/ prefix the following data is encoded
# in urlsafe base64:
# ---------------------------------------------------
# fields | version | user token id | R | ciphertext | MAC |
# ---------------------------------------------------
# | header | | EAX enc data |
# ---------------------------------------------------
# size | 1 | 4 | 32 | ? | 16 |
# ---------------------------------------------------
#
r = urandom(32)
R = calc_dh_base(r)
user_token_id = self.getFromTokenInfo('user_token_id')
data_header = struct.pack('<bI', QRTOKEN_VERSION, user_token_id)
# the user public key is saved as base64 in
# the token info since the byte format is
# incompatible with the json backend.
b64_user_public_key = self.getFromTokenInfo('user_public_key')
user_public_key = b64decode(b64_user_public_key)
ss = calc_dh(r, user_public_key)
U1 = sha256(ss).digest()
U2 = sha256(U1).digest()
zerome(ss)
skA = U1[0:16]
skB = U2[0:16]
nonce = U2[16:32]
zerome(U1)
zerome(U2)
# ------------------------------------------------------------------- --
# create plaintext section
# ------------------------------------------------------------------- --
# create the bitmap for flags
flags = 0
if use_compression:
flags |= CHALLENGE_HAS_COMPRESSION
# FIXME: sizecheck for message, callback url, sms number
# wiki specs are utf-8 byte length (without \0)
if callback_url is not None:
flags |= CHALLENGE_HAS_URL
if callback_sms_number is not None:
flags |= CHALLENGE_HAS_SMS_NUMBER
if (content_type == CONTENT_TYPE_PAIRING):
flags |= CHALLENGE_HAS_SIGNATURE
if reset_url:
flags |= CHALLENGE_SHOULD_RESET_URL
flags |= CHALLENGE_HAS_SIGNATURE
#------------------------------------------------------------------- --
# generate plaintext header
# ----------------------------------------------
# fields | content_type | flags | transaction_id | ... |
# ----------------------------------------------
# size | 1 | 1 | 8 | ? |
# ----------------------------------------------
transaction_id = transaction_id_to_u64(transaction_id)
pt_header = struct.pack('<bbQ', content_type, flags, transaction_id)
plaintext = pt_header
#------------------------------------------------------------------- --
# create data package
# -------------------------------
# fields | header | message | NUL | ... |
# -------------------------------
# size | 10 | ? | 1 | ? |
# -------------------------------
data_package = b''
utf8_message = message.encode('utf8')
# enforce max sizes specified by protocol
if content_type == CONTENT_TYPE_FREE and len(utf8_message) > 511:
raise ParameterError('message (encoded as utf8) can only be 511 '
'characters long')
elif content_type == CONTENT_TYPE_PAIRING and len(utf8_message) > 63:
raise InvalidFunctionParameter('message', 'max string length '
'(encoded as utf8) is 511 for '
'content type PAIRING')
elif content_type == CONTENT_TYPE_AUTH and len(utf8_message) > 511:
raise InvalidFunctionParameter('message', 'max string length '
'(encoded as utf8) is 511 for '
'content type AUTH')
data_package += utf8_message + b'\x00'
# ------------------------------------------------------------------- --
# depending on function parameters add callback url
# and/or callback sms number
# -----------------------------------------------------
# fields | ... | callback url | NUL | callback sms | NUL | ... |
# -----------------------------------------------------
# size | ? | ? | 1 | ? | 1 | ? |
# -----------------------------------------------------
# ------------------------------------------------------------------- --
if callback_url is not None:
utf8_callback_url = callback_url.encode('utf8')
# enforce max url length as specified in protocol
if len(utf8_callback_url) > 511:
raise InvalidFunctionParameter('callback_url', 'max string '
'length (encoded as utf8) is '
'511')
data_package += utf8_callback_url + b'\x00'
# ------------------------------------------------------------------- --
if callback_sms_number is not None:
utf8_callback_sms_number = callback_sms_number.encode('utf8')
if len(utf8_callback_sms_number) > 31:
raise InvalidFunctionParameter('callback_sms_number',
'max string length (encoded '
'as utf8) is 31')
data_package += utf8_callback_sms_number + b'\x00'
# ------------------------------------------------------------------- --
if use_compression:
maybe_compressed_data_package = zlib.compress(data_package, 9)
else:
maybe_compressed_data_package = data_package
# ------------------------------------------------------------------- --
# when content type is pairing the protocol specifies that
# the server must send a hmac based signature with the
# response
sig = ''
sec_obj = self._get_secret_object()
if flags & CHALLENGE_HAS_SIGNATURE:
hmac_message = nonce + pt_header + maybe_compressed_data_package
sig = sec_obj.hmac_digest(data_input=hmac_message,
bkey=self.server_hmac_secret,
hash_algo=sha256)
plaintext += sig
# ------------------------------------------------------------------- --
plaintext += maybe_compressed_data_package
# ------------------------------------------------------------------- --
user_message = nonce + pt_header + sig + data_package
user_sig = sec_obj.hmac_digest(data_input=user_message,
bkey=skB,
hash_algo=sha256)
# the user sig will be given as urlsafe base64 in the
# challenge response. for this reasons (and because we
# need to serialize it into json) we convert the user_sig
# into this format.
user_sig = encode_base64_urlsafe(user_sig)
# ------------------------------------------------------------------- --
cipher = AES.new(skA, AES.MODE_EAX, nonce)
cipher.update(data_header)
ciphertext, tag = cipher.encrypt_and_digest(plaintext)
raw_data = data_header + R + ciphertext + tag
url = 'lseqr://chal/' + encode_base64_urlsafe(raw_data)
return url, user_sig