Exemple #1
0
	def check_their_sig(self, enc_sig, sig_mac, usePrimes=False):
		my_dh_key = self.dh_keys.get_my_cur_keyid()
		if usePrimes:
			cKey = self.dh_keys.cprime
			m1Key = self.dh_keys.m1prime
			m2Key = self.dh_keys.m2prime
		else:
			cKey = self.dh_keys.c
			m1Key = self.dh_keys.m1
			m2Key = self.dh_keys.m2
		
		sig = OtrCrypt.aes_zero_ctr_crypt(cKey, enc_sig)
		#print sig
		
		byte_reader = ByteStreamReader(sig)
		
		their_dsa_key = byte_reader.get_pubkey()
		if their_dsa_key["cipher_code"] != list(OtrConstants["dsa_code_bytes"]):
			return False
		
		# now keyid
		their_dh_keyid = _OT.bytes_to_int(byte_reader.get_int())
		self.dh_keys.associate_their_keyid(their_dh_keyid)
		
		# load their DSA public key - (y,g,p,q)
		their_dsa_key_tup = (
			_OT.mpi_to_int(their_dsa_key["y_mpi"]),
			_OT.mpi_to_int(their_dsa_key["g_mpi"]),
			_OT.mpi_to_int(their_dsa_key["p_mpi"]),
			_OT.mpi_to_int(their_dsa_key["q_mpi"])
		)
		self.dsa_keys.load_their_key(their_dsa_key_tup)
		
		# compute their M factor
		self.compute_their_M_factor(usePrimes=usePrimes)
		
		# now load their signed M factor
		q_len = their_dsa_key["q_len"]
		M_sig_r_factor = _OT.bytes_to_int(byte_reader.get_n_bytes(q_len))
		M_sig_s_factor = _OT.bytes_to_int(byte_reader.get_n_bytes(q_len))
		
		assert (byte_reader.consumed_all())
	
		if not OtrDSA.verify(self.dsa_keys.their_public_key, self.their_M, 
								M_sig_r_factor, M_sig_s_factor):
			logging.debug("DID NOT VERIFY")
			return False
		
		# now check their MAC
		calc_sig_mac = OtrCrypt.get_sha256_hmac_160(m2Key, _OT.bytes_to_data(enc_sig))
		if calc_sig_mac != sig_mac:
			logging.debug( "MAC INCORRECT" )
			#print enc_sig
			#print calc_sig_mac
			#print sig_mac
			return False
		
		# alright, looks like everything checks out 
		return True
Exemple #2
0
	def get_enc_sig_mac(self, usePrimes=False):
		if usePrimes:
			m2Key = self.dh_keys.m2prime
		else:
			m2Key = self.dh_keys.m2
		enc_sig_mac = OtrCrypt.get_sha256_hmac_160(m2Key, _OT.bytes_to_data(self.my_enc_sig))
		self.replay.check('hash_enc_X', enc_sig_mac)
		return enc_sig_mac