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Debugging crypto mismatch
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@tannewt
tannewt committed Jul 26, 2024
1 parent 5f14782 commit 997a65c
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73 changes: 56 additions & 17 deletions circuitmatter/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,10 @@
import pathlib
import json
import os
import pathlib
import secrets
import struct
import time
from ecdsa.ellipticcurve import Point
from ecdsa.ellipticcurve import AbstractPoint, Point, PointJacobi
from ecdsa.curves import NIST256p

from typing import Optional
Expand Down Expand Up @@ -851,17 +851,19 @@ def process_exchange(self, message):
return exchange


M = Point.from_bytes(
M = PointJacobi.from_bytes(
NIST256p.curve,
b"\x02\x88\x6e\x2f\x97\xac\xe4\x6e\x55\xba\x9d\xd7\x24\x25\x79\xf2\x99\x3b\x64\xe1\x6e\xf3\xdc\xab\x95\xaf\xd4\x97\x33\x3d\x8f\xa1\x2f",
)
N = Point.from_bytes(
N = PointJacobi.from_bytes(
NIST256p.curve,
b"\x03\xd8\xbb\xd6\xc6\x39\xc6\x29\x37\xb0\x4d\x99\x7f\x38\xc3\x77\x07\x19\xc6\x29\xd7\x01\x4d\x49\xa2\x4b\x4f\x98\xba\xa1\x29\x2b\x49",
)
CRYPTO_W_SIZE_BYTES = CRYPTO_GROUP_SIZE_BYTES + 8


# in the spake2p math P is NIST256p.generator
# in the spake2p math p is NIST256p.order
def _pbkdf2(passcode, salt, iterations):
ws = hashlib.pbkdf2_hmac(
"sha256", struct.pack("<I", passcode), salt, iterations, CRYPTO_W_SIZE_BYTES * 2
Expand Down Expand Up @@ -890,8 +892,10 @@ def Crypto_pA(w0, w1) -> bytes:
return b""


def Crypto_pB(w0: bytes, L: bytes) -> bytes:
return b""
def Crypto_pB(w0: int, L: Point) -> tuple[int, AbstractPoint]:
y = secrets.randbelow(NIST256p.order)
Y = y * NIST256p.generator + w0 * N
return y, Y


def Crypto_Transcript(context, pA, pB, Z, V, w0) -> bytes:
Expand All @@ -914,9 +918,11 @@ def Crypto_Transcript(context, pA, pB, Z, V, w0) -> bytes:
offset = 0
for e in elements:
struct.pack_into("<Q", tt, offset, len(e))
print(offset, 8, hex(tt[offset]))
offset += 8

tt[offset : offset + len(e)] = e
print(offset, len(e), e.hex(" "))
offset += len(e)
return tt

Expand Down Expand Up @@ -969,6 +975,7 @@ def KDF(salt, key, info):

def Crypto_P2(tt, pA, pB) -> tuple[bytes, bytes, bytes]:
KaKe = Crypto_Hash(tt)
print(f"KaKe[{len(KaKe)}]", KaKe.hex(" "))
Ka = KaKe[: CRYPTO_HASH_LEN_BYTES // 2]
Ke = KaKe[CRYPTO_HASH_LEN_BYTES // 2 :]
# https://github.com/project-chip/connectedhomeip/blob/c88d5cf83cd3e3323ac196630acc34f196a2f405/src/crypto/CHIPCryptoPAL.cpp#L458-L468
Expand Down Expand Up @@ -1087,9 +1094,9 @@ def process_packet(self, address, data):
print(f"Dropping message {message.message_counter}")
return

print(f"Received packet from {address}:")
print(f"{data.hex(' ')}")
print(f"Message counter {message.message_counter}")
# print(f"Received packet from {address}:")
# print(f"{data.hex(' ')}")
# print(f"Message counter {message.message_counter}")
protocol_id = message.protocol_id
protocol_opcode = message.protocol_opcode

Expand All @@ -1105,13 +1112,23 @@ def process_packet(self, address, data):
exchange.commissioning_hash = hashlib.sha256(
b"CHIP PAKE V1 Commissioning"
)
print(
"commissioning hash",
hex(b"CHIP PAKE V1 Commissioning"[0]),
len(b"CHIP PAKE V1 Commissioning"),
)
print(
"Commissioning hash",
hex(message.application_payload[0]),
len(message.application_payload),
)
exchange.commissioning_hash.update(message.application_payload)
if request.passcodeId == 0:
pass
# Send back failure
# response = StatusReport()
# response.GeneralCode
print(request)
# print(request)
response = PBKDFParamResponse()
response.initiatorRandom = request.initiatorRandom

Expand All @@ -1125,7 +1142,10 @@ def process_packet(self, address, data):
params.iterations = self.nonvolatile["iteration-count"]
params.salt = binascii.a2b_base64(self.nonvolatile["salt"])
response.pbkdf_parameters = params
exchange.commissioning_hash.update(response.encode())

encoded = b"\x15" + response.encode() + b"\x18"
print("Commissioning hash", hex(encoded[0]), len(encoded))
exchange.commissioning_hash.update(encoded)
exchange.send(
ProtocolId.SECURE_CHANNEL,
SecureProtocolOpcode.PBKDF_PARAM_RESPONSE,
Expand All @@ -1137,20 +1157,39 @@ def process_packet(self, address, data):
elif protocol_opcode == SecureProtocolOpcode.PASE_PAKE1:
print("Received PASE PAKE1")
pake1 = PAKE1(message.application_payload[1:-1])
print(pake1)
# print(pake1)
pake2 = PAKE2()
print("verifier", self.nonvolatile["verifier"])
verifier = binascii.a2b_base64(self.nonvolatile["verifier"])
w0 = memoryview(verifier)[:CRYPTO_GROUP_SIZE_BYTES]
L = memoryview(verifier)[CRYPTO_GROUP_SIZE_BYTES:]
pake2.pB = Crypto_pB(w0, L)
# TODO: Compute these
Z = b""
V = b""
L = Point.from_bytes(NIST256p.curve, L)
print("w0", w0.hex(" "))
w0 = int.from_bytes(w0, byteorder="big")
print("L", L)
y, Y = Crypto_pB(w0, L)
# pB is Y encoded uncompressed
# pA is X encoded uncompressed
pake2.pB = Y.to_bytes("uncompressed")
h = NIST256p.curve.cofactor()
# Use negation because the class doesn't support subtraction. 🤦
Z = h * y * (Y + (-(w0 * N)))
V = h * y * L
context = exchange.commissioning_hash.digest()
print("context", context.hex(" "))
tt = Crypto_Transcript(
exchange.commissioning_hash.digest(), pake1.pA, pake2.pB, Z, V, w0
context,
pake1.pA,
pake2.pB,
Z.to_bytes("uncompressed"),
V.to_bytes("uncompressed"),
w0.to_bytes(NIST256p.baselen, byteorder="big"),
)
print("transcript", len(tt))
cA, cB, Ke = Crypto_P2(tt, pake1.pA, pake2.pB)
pake2.cB = cB
# print("sending pake2 back")
# print(pake2)
exchange.send(
ProtocolId.SECURE_CHANNEL, SecureProtocolOpcode.PASE_PAKE2, pake2
)
Expand Down
4 changes: 2 additions & 2 deletions test_data/device_state.json
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"descriminator": 2207,
"descriminator": 1983,
"iteration-count": 10000,
"salt": "5uCP0ITHYzI9qBEe6hfU4HfY3y7VopSk0qNvhvznhiQ=",
"verifier": "wxAsyKc/NiJkxkXfi9zu8aVXfMR5zOTmTA2ssdg5B+wEFcTyXODL7NAqAgFIUUvIdgZL3lB7ZoHmQDTroBgAV4ZebS6l5jrklt97N418Wnypeoi9JED6aVVDpmTivkFFUw=="
"verifier": "0xGqxJFBr/ViQt3lv1Yw5F0GcPBAtFFvXB+EcIIjH5cEsjkPZHDQyFWjA6Ide+2gafYnZgIy6gJBgdJOlD8htAZKe0i6nIhT/ADsBWH4CvZcl37n/ofEEECWSEBV4vy/0A=="
}
2 changes: 1 addition & 1 deletion test_data/recorded_packets.json
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Original file line number Diff line number Diff line change
@@ -1 +1 @@
[["receive", 357657266155036, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 45867, 0, 0], "BAAAAObOzQyqpsS5iZt1AwUg70sAABUwASBHe5PONLiOU6V4DJ7DZkokBgIvtdAKtWjuE8CDoN8dPyUCVUQkAwAoBDUFJQH0ASUCLAElA6APJAQRJAULJgYAAAMBJAcBGBg="], ["receive", 357657273325183, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 45867, 0, 0], "BAAAAOfOzQyqpsS5iZt1AwUi70sAABUwAUEEZZRPQKxRLWkU0CZwUU4AJT0cfikv2BmIiAUNWeFqLcoZSI8ULSVK5Re/dNmunfoSd7YojNkgN6L+GJ3TN7ad/xg="], ["receive", 357657652704410, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 45867, 0, 0], "BAAAAOfOzQyqpsS5iZt1AwUi70sAABUwAUEEZZRPQKxRLWkU0CZwUU4AJT0cfikv2BmIiAUNWeFqLcoZSI8ULSVK5Re/dNmunfoSd7YojNkgN6L+GJ3TN7ad/xg="], ["receive", 357658002105028, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 45867, 0, 0], "BAAAAOfOzQyqpsS5iZt1AwUi70sAABUwAUEEZZRPQKxRLWkU0CZwUU4AJT0cfikv2BmIiAUNWeFqLcoZSI8ULSVK5Re/dNmunfoSd7YojNkgN6L+GJ3TN7ad/xg="], ["receive", 357658622312059, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 45867, 0, 0], "BAAAAOfOzQyqpsS5iZt1AwUi70sAABUwAUEEZZRPQKxRLWkU0CZwUU4AJT0cfikv2BmIiAUNWeFqLcoZSI8ULSVK5Re/dNmunfoSd7YojNkgN6L+GJ3TN7ad/xg="], ["receive", 357659576369391, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 45867, 0, 0], "BAAAAOfOzQyqpsS5iZt1AwUi70sAABUwAUEEZZRPQKxRLWkU0CZwUU4AJT0cfikv2BmIiAUNWeFqLcoZSI8ULSVK5Re/dNmunfoSd7YojNkgN6L+GJ3TN7ad/xg="]]
[["receive", 22019542334443, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 56921, 0, 0], "BAAAABKaPgrv6cJyqUaC6gUg/GsAABUwASB1xjIG0TZ6FcxVP4D/UaOXMLwYZk5bTZIC3ASnMUvA2iUCe9YkAwAoBDUFJQH0ASUCLAElA6APJAQRJAULJgYAAAMBJAcBGBg="], ["receive", 22019548962619, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 56921, 0, 0], "BAAAABOaPgrv6cJyqUaC6gUi/GsAABUwAUEENxA7hCA0cyjIm09EgPW/LHBoZpeY/4MF0YmZTtjPgFaVuA+qHWGWW3zv2u37ySGlKnMM4xKKTpclVmio+H8dKhg="], ["receive", 22019565022443, ["fd98:bbab:bd61:8040:642:1aff:fe0c:9f2a", 56921, 0, 0], "BAAAABSaPgrv6cJyqUaC6gVA/GsAAAEAAAAAAAIA"]]

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