trezor-firmware/tests/device_tests/misc/test_cosi.py

# This file is part of the Trezor project.
#
# Copyright (C) 2012-2019 SatoshiLabs and contributors
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the License along with this library.
# If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.

from hashlib import sha256

import pytest

from trezorlib import cosi
from trezorlib.tools import parse_path

pytestmark = pytest.mark.skip_t2


def test_cosi_commit(client):
    digest = sha256(b"this is a message").digest()

    c0 = cosi.commit(client, parse_path("10018'/0'"), digest)
    c1 = cosi.commit(client, parse_path("10018'/1'"), digest)
    c2 = cosi.commit(client, parse_path("10018'/2'"), digest)

    assert c0.pubkey != c1.pubkey
    assert c0.pubkey != c2.pubkey
    assert c1.pubkey != c2.pubkey

    assert c0.commitment != c1.commitment
    assert c0.commitment != c2.commitment
    assert c1.commitment != c2.commitment

    digestb = sha256(b"this is a different message").digest()

    c0b = cosi.commit(client, parse_path("10018'/0'"), digestb)
    c1b = cosi.commit(client, parse_path("10018'/1'"), digestb)
    c2b = cosi.commit(client, parse_path("10018'/2'"), digestb)

    assert c0.pubkey == c0b.pubkey
    assert c1.pubkey == c1b.pubkey
    assert c2.pubkey == c2b.pubkey

    assert c0.commitment != c0b.commitment
    assert c1.commitment != c1b.commitment
    assert c2.commitment != c2b.commitment


def test_cosi_sign(client):
    digest = sha256(b"this is a message").digest()

    c0 = cosi.commit(client, parse_path("10018'/0'"), digest)
    c1 = cosi.commit(client, parse_path("10018'/1'"), digest)
    c2 = cosi.commit(client, parse_path("10018'/2'"), digest)

    global_pk = cosi.combine_keys([c0.pubkey, c1.pubkey, c2.pubkey])
    global_R = cosi.combine_keys([c0.commitment, c1.commitment, c2.commitment])

    # fmt: off
    sig0 = cosi.sign(client, parse_path("10018'/0'"), digest, global_R, global_pk)
    sig1 = cosi.sign(client, parse_path("10018'/1'"), digest, global_R, global_pk)
    sig2 = cosi.sign(client, parse_path("10018'/2'"), digest, global_R, global_pk)
    # fmt: on

    sig = cosi.combine_sig(global_R, [sig0.signature, sig1.signature, sig2.signature])

    cosi.verify_combined(sig, digest, global_pk)


def test_cosi_compat(client):
    digest = sha256(b"this is not a pipe").digest()
    remote_commit = cosi.commit(client, parse_path("10018'/0'"), digest)

    local_privkey = sha256(b"private key").digest()[:32]
    local_pubkey = cosi.pubkey_from_privkey(local_privkey)
    local_nonce, local_commitment = cosi.get_nonce(local_privkey, digest, 42)

    global_pk = cosi.combine_keys([remote_commit.pubkey, local_pubkey])
    global_R = cosi.combine_keys([remote_commit.commitment, local_commitment])

    remote_sig = cosi.sign(client, parse_path("10018'/0'"), digest, global_R, global_pk)
    local_sig = cosi.sign_with_privkey(
        digest, local_privkey, global_pk, local_nonce, global_R
    )
    sig = cosi.combine_sig(global_R, [remote_sig.signature, local_sig])

    cosi.verify_combined(sig, digest, global_pk)