From fe6f9450f0d29d9986cd0558ea285ef3f8a2b7d2 Mon Sep 17 00:00:00 2001
From: M1nd3r <petrsedlacek.km@seznam.cz>
Date: Mon, 17 Feb 2025 17:10:45 +0100
Subject: [PATCH] chore(core): update cpace implementation [no changelog]
---
core/src/apps/thp/pairing.py | 2 +-
core/src/trezor/wire/thp/cpace.py | 8 ++++++--
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/core/src/apps/thp/pairing.py b/core/src/apps/thp/pairing.py
index 195dc14e2b..404713ce72 100644
--- a/core/src/apps/thp/pairing.py
+++ b/core/src/apps/thp/pairing.py
@@ -220,7 +220,7 @@ async def _handle_code_entry_is_selected_first_time(ctx: PairingContext) -> None
ctx.channel_ctx.get_handshake_hash(),
)
assert ctx.code_code_entry is not None
- ctx.cpace.generate_keys_and_secret(ctx.code_code_entry.to_bytes(6, "big"))
+ ctx.cpace.generate_keys(ctx.code_code_entry.to_bytes(6, "big"))
await ctx.write_force(
ThpCodeEntryCpaceTrezor(cpace_trezor_public_key=ctx.cpace.trezor_public_key)
)
diff --git a/core/src/trezor/wire/thp/cpace.py b/core/src/trezor/wire/thp/cpace.py
index fad0f705d3..76344e65ef 100644
--- a/core/src/trezor/wire/thp/cpace.py
+++ b/core/src/trezor/wire/thp/cpace.py
@@ -17,9 +17,9 @@ class Cpace:
self.trezor_private_key: bytes
self.trezor_public_key: bytes
- def generate_keys_and_secret(self, code_code_entry: bytes) -> None:
+ def generate_keys(self, code_code_entry: bytes) -> None:
"""
- Generate ephemeral key pair and a shared secret using Elligator2 with X25519.
+ Generate an ephemeral key pair using Elligator2 with X25519.
"""
sha_ctx = sha512(_PREFIX)
sha_ctx.update(code_code_entry)
@@ -32,6 +32,10 @@ class Cpace:
self.trezor_public_key = curve25519.multiply(self.trezor_private_key, generator)
def compute_shared_secret(self, host_public_key: bytes) -> None:
+ """
+ Compute a shared secret using host's public (cpace) key.
+ Must be called after `generate_keys`.
+ """
self.shared_secret = curve25519.multiply(
self.trezor_private_key, host_public_key
)