trezor-firmware/tests/device_tests/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


@pytest.mark.skip_t2
class TestCosi:
    def test_cosi_commit(self, 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(self, 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(sig, digest, global_pk)

    def test_cosi_compat(self, 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(sig, digest, global_pk)