def process_challenge(self, bytes_s: bytes, bytes_B: bytes) -> Any:
s = bytes_to_long(bytes_s)
B = bytes_to_long(bytes_B)
N = self.N
g = self.g
k = self.k
hash_class = self.hash_class
# SRP-6a safety check
if (B % N) == 0:
return None
u = H(hash_class, self.A, B, width=len(long_to_bytes(N)))
if u == 0: # SRP-6a safety check
return None
x = calculate_x(hash_class, s, self.Iu, self.p)
v = pow(g, x, N)
S = pow((B - k * v), (self.a + u * x), N)
self.K = hash_class(long_to_bytes(S)).digest()
M = calculate_M(hash_class, N, g, self.Iu, s, self.A, B, self.K)
if not M:
return None
self.H_AMK = calculate_H_AMK(hash_class, self.A, M, self.K)
return M
def generate_salt_and_verifier(Iu: str, p: str, len_s: int, hash_alg: int = SHA512, ng_type: int = NG_3072) -> Tuple[bytes, bytes]:
hash_class = _hash_map[hash_alg]
N, g = get_ng(ng_type)
_s = long_to_bytes(get_random(len_s))
_v = long_to_bytes(pow(g, calculate_x(hash_class, _s, Iu, p), N))
return _s, _v
def calculate_M(hash_class: Callable, N: int, g: int, Iu: str, s: int, A: int, B: int, K: bytes) -> Any:
_Iu = Iu.encode()
h = hash_class()
h.update(H_N_xor_g(hash_class, N, g))
h.update(hash_class(_Iu).digest())
h.update(long_to_bytes(s))
h.update(long_to_bytes(A))
h.update(long_to_bytes(B))
h.update(K)
return h.digest()
def H_N_xor_g(hash_class: Callable, N: int, g: int) -> bytes:
bin_N = long_to_bytes(N)
bin_g = long_to_bytes(g)
padding = len(bin_N) - len(bin_g)
hN = hash_class(bin_N).digest()
hg = hash_class(b''.join([b'\0' * padding, bin_g])).digest()
return b''.join(long_to_bytes(hN[i] ^ hg[i]) for i in range(0, len(hN)))
def H(hash_class: Callable, *args: Any, **kwargs: Any) -> int:
width = kwargs.get('width', None)
h = hash_class()
for s in args:
if s is not None:
data = long_to_bytes(s) if isinstance(s, int) else s
if width is not None:
h.update(bytes(width - len(data)))
h.update(data)
return int(h.hexdigest(), 16)
def sign(curve, private_key, digest):
q = curve.q
e = bytes_to_long(digest) % q
if e == 0:
e = 1
while True:
k = bytes_to_long(urandom(MODE_SIZE)) % q
if k == 0:
continue
r, _ = curve.scalar_multiply(k)
r %= q
if r == 0:
continue
d = private_key * r
k *= e
s = (d + k) % q
if s == 0:
continue
return long_to_bytes(s, MODE_SIZE) + long_to_bytes(r, MODE_SIZE)
def setup0_request(self) -> Any:
# Form SessionCmd0 request packet using client public key
setup_req = proto.session_pb2.SessionData()
setup_req.sec_ver = proto.session_pb2.SecScheme2
setup_req.sec2.msg = proto.sec2_pb2.S2Session_Command0
setup_req.sec2.sc0.client_username = str_to_bytes(self.username)
self.srp6a_ctx = Srp6a(self.username, self.password)
if self.srp6a_ctx is None:
raise RuntimeError('Failed to initialize SRP6a instance!')
client_pubkey = long_to_bytes(self.srp6a_ctx.A)
setup_req.sec2.sc0.client_pubkey = client_pubkey
self._print_verbose(f'Client Public Key:\t0x{client_pubkey.hex()}')
return setup_req.SerializeToString().decode('latin-1')
def __init__(self, username: str, password: str, hash_alg: int = SHA512, ng_type: int = NG_3072):
hash_class = _hash_map[hash_alg]
N, g = get_ng(ng_type)
k = H(hash_class, N, g, width=len(long_to_bytes(N)))
self.Iu = username
self.p = password
self.a = get_random_of_length(32)
self.A = pow(g, self.a, N)
self.v: Optional[int] = None
self.K: Optional[bytes] = None
self.H_AMK = None
self._authenticated = False
self.hash_class = hash_class
self.N = N
self.g = g
self.k = k
from lab4.elgamal import ElGamal from utils import bytes_to_long, long_to_bytes bit_length = 2048 # elgamal = ElGamal(bit_length)? elgamal = ElGamal() elgamal.save_config() # m = maurer_generator(512) m = b'Hello World' m_number = bytes_to_long(m) + elgamal.p + elgamal.p print(long_to_bytes(elgamal.decrypt(*elgamal.encrypt(m_number))))
def start_authentication(self) -> Tuple[str, bytes]:
return (self.Iu, long_to_bytes(self.A))
def get_ephemeral_secret(self) -> Any:
return long_to_bytes(self.a)
def calculate_H_AMK(hash_class: Callable, A: int, M: bytes, K: bytes) -> Any:
h = hash_class()
h.update(long_to_bytes(A))
h.update(M)
h.update(K)
return h.digest()
def a_xor_b(a: bytes, b: bytes) -> bytes:
return b''.join(long_to_bytes(a[i] ^ b[i]) for i in range(0, len(b)))
