def int_from_bytes(bytes_, byteorder='little'): """ converts bytes to an integer :param bytes_: The bytes, that should be converted :param byteorder: 'little' for little endian (default) or 'big' for big endian """ if byteorder not in ['little', 'big']: raise InvalidFunctionParameter( 'byteorder', 'byte order can only ' 'be \'little\' or \'big\'') order = -1 if byteorder == 'little' else 1 # we calculate the result by interpreting data as coefficients of the # polynomial # # p(X) := data[15] * X^15 + ... + data[1] * X + data[0] # # and evulating p(2^8) using horner's scheme. res = 0 for byte in bytes_[::order]: res *= 256 res += ord(byte) return res
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, sig_base), with challenge_url being the push url and sig_base the message, that is used for the client signature """ 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 | timestamp | .. # ------------------------------------------------ # size | 1 | 8 | 8 | ? # ------------------------------------------------- transaction_id = transaction_id_to_u64(transaction_id) plaintext = struct.pack('<bQQ', content_type, transaction_id, int(time.time())) # ------------------------------------------------------------------- -- 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, (signature + 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(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