def sign(self, data):
if self.replay.can_replay("k"):
k = self.replay.data["k"]
else:
k = random.SystemRandom().randint(2, self.my_private_key.q - 1)
r, s = self.my_private_key.sign(_OT.bytes_to_string(data), k)
ra = _OT.zero_pad(_OT.int_to_bytes(r), self.my_q_len)
sa = _OT.zero_pad(_OT.int_to_bytes(s), self.my_q_len)
return ra + sa
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 compute_their_M_factor(self, usePrimes=False): my_dh_keyid = self.dh_keys.get_my_cur_keyid() their_dh_keyid = self.dh_keys.get_their_cur_keyid() if usePrimes: m1PrimeKey = self.dh_keys.m1prime else: m1PrimeKey = self.dh_keys.m1 # Compute the 32-byte value MA to be the SHA256-HMAC of the following data, using the key m1': mbytes = [] # gy (MPI) mbytes.extend( self.dh_keys.their_public_factor_to_mpi(their_dh_keyid) ) # gx (MPI) mbytes.extend( self.dh_keys.my_public_factor_to_mpi(my_dh_keyid) ) # pubA (PUBKEY) mbytes.extend( OtrDSA.format_key(self.dsa_keys.their_public_key) ) # keyidA (INT) keyid = _OT.zero_pad(_OT.int_to_bytes(their_dh_keyid), 4) mbytes.extend( keyid ) self.their_M = OtrCrypt.get_sha256_hmac(m1PrimeKey, mbytes)
def compute_my_M_and_X_values(self, usePrimes=False):
my_dh_keyid = self.dh_keys.get_my_cur_keyid()
if usePrimes:
cKey = self.dh_keys.cprime
m1Key = self.dh_keys.m1prime
else:
cKey = self.dh_keys.c
m1Key = self.dh_keys.m1
# Compute the 32-byte value MB to be the SHA256-HMAC of the following data, using the key m1:
mbytes = []
# gx (MPI)
mbytes.extend( self.dh_keys.my_public_factor_to_mpi(my_dh_keyid) )
# gy (MPI)
mbytes.extend( self.dh_keys.their_public_factor_to_mpi() )
# pubB (PUBKEY)
mbytes.extend( OtrDSA.format_key(self.dsa_keys.my_public_key) )
# keyidB (INT)
keyid = _OT.zero_pad(_OT.int_to_bytes(my_dh_keyid), 4)
mbytes.extend( keyid )
self.replay.check('M', mbytes)
my_M = OtrCrypt.get_sha256_hmac(m1Key, mbytes)
self.replay.check('hash_M', my_M)
# Let XB be the following structure:
xbytes = []
# pubB (PUBKEY)
xbytes.extend( OtrDSA.format_key(self.dsa_keys.my_public_key) )
# keyidB (INT)
xbytes.extend( keyid )
# sigB(MB) (SIG)
# This is the signature, using the private part of the key pubB, of the 32-byte MB
# (which does not need to be hashed again to produce the signature).
xbytes.extend( self.dsa_keys.sign( my_M ) )
my_X = xbytes
self.replay.check('X', my_X)
# Encrypt XB using AES128-CTR with key c and initial counter value 0.
self.my_enc_sig = OtrCrypt.aes_zero_ctr_crypt(cKey, my_X)
self.replay.check('enc_X', self.my_enc_sig)
def __call__(self): c = _OT.int_to_bytes(self.count) self.count += 1 return _OT.bytes_to_string(_OT.zero_pad(c, 16))
