def encrypt_data_message(self, msg): #global memo # encrypt the message counter = _OT.zero_pad(_OT.int_to_bytes(self.ctr), 8) enc_msg = OtrCrypt.aes_ctr_crypt(self.send_aes_key, msg, self.ctr) memo.enc_msg = enc_msg flags = [0x00] #memo.flags = flags # generate T = (my_keyid, their_keyid, next_dh, ctr, AES-CTR_ek,ctr(msg)) T = [0,2,3, flags[0]] # protocol version and msg code # my_keyid sender_keyid = _OT.zero_pad(_OT.int_to_bytes(self.my_sess_keyid), 4) #memo.sender_keyid = sender_keyid T.extend( sender_keyid ) # their_keyid recipient_keyid = _OT.zero_pad(_OT.int_to_bytes(self.their_sess_keyid), 4) #memo.recipient_keyid = recipient_keyid T.extend( recipient_keyid ) # next_dh next_dh = _OT.int_to_mpi(self.next_dh) #memo.next_dh = next_dh T.extend( next_dh ) # ctr #memo.counter = counter T.extend( counter ) # enc_msg T.extend( _OT.bytes_to_data(enc_msg) ) #memo.T = T # compute MAC_mk(T) authenticator = OtrCrypt.get_sha1_hmac(self.send_mac_key, T) #memo.authenticator = authenticator #memo.old_mac_keys = self.old_mac_keys #memo.send_mac_key = self.send_mac_key #memo.recv_mac_key = self.recv_mac_key #memo.send_aes_key = self.send_aes_key #memo.recv_aes_key = self.recv_aes_key #memo.secbytes = self.secbytes #memo.sender_factor = self.my_public_factor_to_mpi(self.my_sess_keyid) #print "SENDER" #for x in sorted(self.my_public_factors.keys()): # print (x, self.my_public_factor_to_mpi(x)) #r = raw_input() #memo.recipient_factor = self.their_public_factor_to_mpi(self.their_sess_keyid) return (flags, sender_keyid, recipient_keyid, next_dh, counter, _OT.bytes_to_data(enc_msg), authenticator, _OT.bytes_to_data(self.old_mac_keys))
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
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
def get_enc_sig(self): return _OT.bytes_to_data(self.my_enc_sig)
def get_r_secret(self): return _OT.bytes_to_data(self.r_secret)
def hash_my_public_factor_mpi(self, my_keyid=None): hash_gxmpi = OtrCrypt.get_sha256_bytes(self.my_public_factor_to_mpi(my_keyid)) # RCHANGE if self.authing: self.replay.check('hash_dh_factor', hash_gxmpi) hash_gxmpi_data = _OT.bytes_to_data(hash_gxmpi) return hash_gxmpi_data
def encrypt_my_public_factor_mpi(self, my_keyid=None): enc_gxmpi = OtrCrypt.aes_zero_ctr_crypt(self.r_secret, self.my_public_factor_to_mpi(my_keyid)) # RCHANGE if self.authing: self.replay.check('enc_dh_factor', enc_gxmpi) enc_gxmpi_data = _OT.bytes_to_data(enc_gxmpi) return enc_gxmpi_data