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factor out key-derivation, prepare for change

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This commit is contained in:
Brian Warner 2016-05-24 13:26:08 -07:00
parent b72f0ce934
commit 7c8e5fb062
1 changed files with 11 additions and 4 deletions
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15
src/wormhole/wormhole.py
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@ -533,11 +533,14 @@ class _Wormhole:
self._key = self._sp.finish(pake_msg) self._key = self._sp.finish(pake_msg)
self._event_established_key() self._event_established_key()
def _derive_confirmation_key(self):
return self._derive_key(u"wormhole:confirmation")
def _event_established_key(self): def _event_established_key(self):
self._timing.add("key established") self._timing.add("key established")
# both sides send different (random) confirmation messages # both sides send different (random) confirmation messages
confkey = self._derive_key(u"wormhole:confirmation") confkey = self._derive_confirmation_key()
nonce = os.urandom(CONFMSG_NONCE_LENGTH) nonce = os.urandom(CONFMSG_NONCE_LENGTH)
confmsg = make_confmsg(confkey, nonce) confmsg = make_confmsg(confkey, nonce)
self._msg_send(u"confirm", confmsg) self._msg_send(u"confirm", confmsg)
@ -571,7 +574,7 @@ class _Wormhole:
# TODO: we might not have a master key yet, if the caller wasn't # TODO: we might not have a master key yet, if the caller wasn't
# waiting in _get_master_key() when a back-to-back pake+_confirm # waiting in _get_master_key() when a back-to-back pake+_confirm
# message pair arrived. # message pair arrived.
confkey = self._derive_key(u"wormhole:confirmation") confkey = self._derive_confirmation_key()
nonce = body[:CONFMSG_NONCE_LENGTH] nonce = body[:CONFMSG_NONCE_LENGTH]
if body != make_confmsg(confkey, nonce): if body != make_confmsg(confkey, nonce):
# this makes all API calls fail # this makes all API calls fail
@ -589,6 +592,10 @@ class _Wormhole:
with self._timing.add("API send", phase=phase): with self._timing.add("API send", phase=phase):
self._maybe_send_phase_messages() self._maybe_send_phase_messages()
#def _derive_phase_key(self, side, phase):
def _derive_phase_key(self, phase):
return self._derive_key(u"wormhole:phase:%s" % phase)
def _maybe_send_phase_messages(self): def _maybe_send_phase_messages(self):
# TODO: deal with reentrant call # TODO: deal with reentrant call
if not (self._connection_state == OPEN if not (self._connection_state == OPEN
@ -600,7 +607,7 @@ class _Wormhole:
for pm in plaintexts: for pm in plaintexts:
(phase, plaintext) = pm (phase, plaintext) = pm
assert isinstance(phase, int), type(phase) assert isinstance(phase, int), type(phase)
data_key = self._derive_key(u"wormhole:phase:%d" % phase) data_key = self._derive_phase_key(u"%d" % phase)
encrypted = self._encrypt_data(data_key, plaintext) encrypted = self._encrypt_data(data_key, plaintext)
self._msg_send(u"%d" % phase, encrypted) self._msg_send(u"%d" % phase, encrypted)
@ -672,7 +679,7 @@ class _Wormhole:
# It's a phase message, aimed at the application above us. Decrypt # It's a phase message, aimed at the application above us. Decrypt
# and deliver upstairs, notifying anyone waiting on it # and deliver upstairs, notifying anyone waiting on it
try: try:
data_key = self._derive_key(u"wormhole:phase:%s" % phase) data_key = self._derive_phase_key(phase)
plaintext = self._decrypt_data(data_key, body) plaintext = self._decrypt_data(data_key, body)
except CryptoError: except CryptoError:
e = WrongPasswordError() e = WrongPasswordError()