open.source/magic-wormhole
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

transcribe.py: properly encrypt the transferred data

Browse Source
This commit is contained in:
Brian Warner 2015-02-11 02:09:08 -08:00
parent 04ef43f872
commit a67d6365f8
2 changed files with 195 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

161
src/wormhole/hkdf.py Normal file
View File

@ -0,0 +1,161 @@
from hashlib import sha256, sha1
import hmac
import six
def HKDF(SKM, dkLen, XTS=None, CTXinfo=b"", digest=sha256,
_test_expected_PRK=None):
assert isinstance(SKM, six.binary_type)
assert isinstance(XTS, (six.binary_type,type(None)))
assert isinstance(CTXinfo, six.binary_type)
hlen = len(digest(b"").digest())
assert dkLen <= hlen*255
if XTS is None:
XTS = b"\x00"*hlen
# extract
PRK = hmac.new(XTS, SKM, digest).digest()
if _test_expected_PRK and _test_expected_PRK != PRK:
raise ValueError("test failed")
# expand
blocks = []
counter = 1
t = b""
while hlen*len(blocks) < dkLen:
t = hmac.new(PRK, t+CTXinfo+six.int2byte(counter), digest).digest()
blocks.append(t)
counter += 1
return b"".join(blocks)[:dkLen]
def power_on_self_test():
from binascii import hexlify, unhexlify
def _test(IKM, salt, info, L, PRK, OKM, digest=sha256):
def remove_prefix(prefix, s):
assert s.startswith(prefix)
return s[len(prefix):]
ikm = unhexlify(remove_prefix("0x", IKM))
salt = unhexlify(remove_prefix("0x", salt))
info = unhexlify(remove_prefix("0x", info))
prk = unhexlify(remove_prefix("0x", PRK))
okm = unhexlify(remove_prefix("0x", OKM))
if digest is None:
out = HKDF(ikm, L, salt, info, _test_expected_PRK=prk)
else:
out = HKDF(ikm, L, salt, info, digest=digest,
_test_expected_PRK=prk)
if okm != out:
raise ValueError("got %s, expected %s" % (hexlify(out), hexlify(okm)))
# test vectors from RFC5869
_test(IKM="0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
salt="0x000102030405060708090a0b0c",
info="0xf0f1f2f3f4f5f6f7f8f9",
L=42,
PRK=("0x077709362c2e32df0ddc3f0dc47bba63"
"90b6c73bb50f9c3122ec844ad7c2b3e5"),
OKM=("0x3cb25f25faacd57a90434f64d0362f2a"
"2d2d0a90cf1a5a4c5db02d56ecc4c5bf"
"34007208d5b887185865"))
_test(IKM=("0x000102030405060708090a0b0c0d0e0f"
"101112131415161718191a1b1c1d1e1f"
"202122232425262728292a2b2c2d2e2f"
"303132333435363738393a3b3c3d3e3f"
"404142434445464748494a4b4c4d4e4f"),
salt=("0x606162636465666768696a6b6c6d6e6f"
"707172737475767778797a7b7c7d7e7f"
"808182838485868788898a8b8c8d8e8f"
"909192939495969798999a9b9c9d9e9f"
"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf"),
info=("0xb0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
"c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
"d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
"e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"),
L=82,
PRK=("0x06a6b88c5853361a06104c9ceb35b45c"
"ef760014904671014a193f40c15fc244"),
OKM=("0xb11e398dc80327a1c8e7f78c596a4934"
"4f012eda2d4efad8a050cc4c19afa97c"
"59045a99cac7827271cb41c65e590e09"
"da3275600c2f09b8367793a9aca3db71"
"cc30c58179ec3e87c14c01d5c1f3434f"
"1d87"))
_test(IKM="0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
salt="0x",
info="0x",
L=42,
PRK=("0x19ef24a32c717b167f33a91d6f648bdf"
"96596776afdb6377ac434c1c293ccb04"),
OKM=("0x8da4e775a563c18f715f802a063c5a31"
"b8a11f5c5ee1879ec3454e5f3c738d2d"
"9d201395faa4b61a96c8"))
_test(digest=sha1,
IKM="0x0b0b0b0b0b0b0b0b0b0b0b",
salt="0x000102030405060708090a0b0c",
info="0xf0f1f2f3f4f5f6f7f8f9",
L=42,
PRK="0x9b6c18c432a7bf8f0e71c8eb88f4b30baa2ba243",
OKM=("0x085a01ea1b10f36933068b56efa5ad81"
"a4f14b822f5b091568a9cdd4f155fda2"
"c22e422478d305f3f896"))
_test(digest=sha1,
IKM=("0x000102030405060708090a0b0c0d0e0f"
"101112131415161718191a1b1c1d1e1f"
"202122232425262728292a2b2c2d2e2f"
"303132333435363738393a3b3c3d3e3f"
"404142434445464748494a4b4c4d4e4f"),
salt=("0x606162636465666768696a6b6c6d6e6f"
"707172737475767778797a7b7c7d7e7f"
"808182838485868788898a8b8c8d8e8f"
"909192939495969798999a9b9c9d9e9f"
"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf"),
info=("0xb0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
"c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
"d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
"e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"),
L=82,
PRK="0x8adae09a2a307059478d309b26c4115a224cfaf6",
OKM=("0x0bd770a74d1160f7c9f12cd5912a06eb"
"ff6adcae899d92191fe4305673ba2ffe"
"8fa3f1a4e5ad79f3f334b3b202b2173c"
"486ea37ce3d397ed034c7f9dfeb15c5e"
"927336d0441f4c4300e2cff0d0900b52"
"d3b4"))
_test(digest=sha1,
IKM="0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
salt="0x",
info="0x",
L=42,
PRK="0xda8c8a73c7fa77288ec6f5e7c297786aa0d32d01",
OKM=("0x0ac1af7002b3d761d1e55298da9d0506"
"b9ae52057220a306e07b6b87e8df21d0"
"ea00033de03984d34918"))
_test(digest=sha1,
IKM="0x0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c",
salt="0x",
info="0x",
L=42,
PRK="0x2adccada18779e7c2077ad2eb19d3f3e731385dd",
OKM=("0x2c91117204d745f3500d636a62f64f0a"
"b3bae548aa53d423b0d1f27ebba6f5e5"
"673a081d70cce7acfc48"))
# finally test that HKDF() without a digest= uses SHA256
_test(digest=None,
IKM="0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
salt="0x",
info="0x",
L=42,
PRK=("0x19ef24a32c717b167f33a91d6f648bdf"
"96596776afdb6377ac434c1c293ccb04"),
OKM=("0x8da4e775a563c18f715f802a063c5a31"
"b8a11f5c5ee1879ec3454e5f3c738d2d"
"9d201395faa4b61a96c8"))
#print "all test passed"
power_on_self_test()

44
src/wormhole/transcribe.py
View File

@ -1,6 +1,9 @@
import time, requests, json
from binascii import hexlify, unhexlify
from spake2 import SPAKE2_A, SPAKE2_B
from nacl.secret import SecretBox
from nacl import utils
from .hkdf import HKDF
from .const import RELAY
from .codes import make_code, extract_channel_id
@ -51,8 +54,14 @@ class Common:
key = self.sp.finish(pake_msg)
return key
def _post_data(self):
post_data = json.dumps({"message": hexlify(self.data).decode("ascii")})
def _encrypt_data(self, key, data):
assert len(key) == SecretBox.KEY_SIZE
box = SecretBox(key)
nonce = utils.random(SecretBox.NONCE_SIZE)
return box.encrypt(self.data, nonce)
def _post_data(self, data):
post_data = json.dumps({"message": hexlify(data).decode("ascii")})
r = requests.post(self.url("data/post"), data=post_data)
r.raise_for_status()
other_msgs = r.json()["messages"]
@ -63,6 +72,12 @@ class Common:
data = unhexlify(msgs[0].encode("ascii"))
return data
def _decrypt_data(self, key, encrypted):
assert len(key) == SecretBox.KEY_SIZE
box = SecretBox(key)
data = box.decrypt(encrypted)
return data
def _deallocate(self):
r = requests.post(self.url("deallocate"))
r.raise_for_status()
@ -88,13 +103,17 @@ class Initiator(Common):
return self.code
def get_data(self):
self.key = self._poll_pake([])
key = self._poll_pake([])
outbound_key = HKDF(key, SecretBox.KEY_SIZE, CTXinfo=b"sender")
outbound_encrypted = self._encrypt_data(outbound_key, self.data)
other_msgs = self._post_data(outbound_encrypted)
other_msgs = self._post_data()
data = self._poll_data(other_msgs)
inbound_encrypted = self._poll_data(other_msgs)
inbound_key = HKDF(key, SecretBox.KEY_SIZE, CTXinfo=b"receiver")
inbound_data = self._decrypt_data(inbound_key, inbound_encrypted)
self._deallocate()
return data
return inbound_data
class Receiver(Common):
def __init__(self, appid, data, code, relay=RELAY):
@ -114,10 +133,15 @@ class Receiver(Common):
def get_data(self):
other_msgs = self._post_pake()
self.key = self._poll_pake(other_msgs)
key = self._poll_pake(other_msgs)
other_msgs = self._post_data()
data = self._poll_data(other_msgs)
outbound_key = HKDF(key, SecretBox.KEY_SIZE, CTXinfo=b"receiver")
outbound_encrypted = self._encrypt_data(outbound_key, self.data)
other_msgs = self._post_data(outbound_encrypted)
inbound_encrypted = self._poll_data(other_msgs)
inbound_key = HKDF(key, SecretBox.KEY_SIZE, CTXinfo=b"sender")
inbound_data = self._decrypt_data(inbound_key, inbound_encrypted)
self._deallocate()
return data
return inbound_data