blob: 5ad10dd6cd75ca6b8524c264f87406484f7ec9d5 [file] [log] [blame]
#!/usr/bin/env python3
#
# Copyright (c) 2022 Project CHIP Authors
# All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import argparse
import base64
import hashlib
import struct
from ecdsa.curves import NIST256p
# Forbidden passcodes as listed in the "5.1.7.1. Invalid Passcodes" section of the Matter spec
INVALID_PASSCODES = [00000000,
11111111,
22222222,
33333333,
44444444,
55555555,
66666666,
77777777,
88888888,
99999999,
12345678,
87654321, ]
# Length of `w0s` and `w1s` elements
WS_LENGTH = NIST256p.baselen + 8
def generate_verifier(passcode: int, salt: bytes, iterations: int) -> bytes:
ws = hashlib.pbkdf2_hmac('sha256', struct.pack('<I', passcode), salt, iterations, WS_LENGTH * 2)
w0 = int.from_bytes(ws[:WS_LENGTH], byteorder='big') % NIST256p.order
w1 = int.from_bytes(ws[WS_LENGTH:], byteorder='big') % NIST256p.order
L = NIST256p.generator * w1
return w0.to_bytes(NIST256p.baselen, byteorder='big') + L.to_bytes('uncompressed')
def main():
def passcode_arg(arg: str) -> int:
passcode = int(arg)
if not 0 <= passcode <= 99999999:
raise argparse.ArgumentTypeError('passcode out of range')
if passcode in INVALID_PASSCODES:
raise argparse.ArgumentTypeError('invalid passcode')
return passcode
def salt_arg(arg: str) -> bytes:
salt = base64.b64decode(arg)
if not 16 <= len(salt) <= 32:
raise argparse.ArgumentTypeError('invalid salt length')
return salt
def iterations_arg(arg: str) -> int:
iterations = int(arg)
if not 1000 <= iterations <= 100000:
raise argparse.ArgumentTypeError('iteration count out of range')
return iterations
parser = argparse.ArgumentParser(description='SPAKE2+ Python Tool', fromfile_prefix_chars='@')
commands = parser.add_subparsers(dest='command', metavar='subcommand'.ljust(16), required=True)
gen_verifier = commands.add_parser('gen-verifier', help='Generate SPAKE2+ Verifier')
gen_verifier.add_argument('-p', '--passcode', type=passcode_arg,
required=True, help='8-digit passcode')
gen_verifier.add_argument('-s', '--salt', type=salt_arg,
required=True, help='Salt of length 16 to 32 octets encoded in Base64')
gen_verifier.add_argument('-i', '--iteration-count', type=iterations_arg,
metavar='count', required=True, help='Iteration count between 1000 and 100000')
args = parser.parse_args()
if args.command == 'gen-verifier':
verifier = generate_verifier(args.passcode, args.salt, args.iteration_count)
print(base64.b64encode(verifier).decode('ascii'))
if __name__ == '__main__':
main()