unit_tests: added test suite for Ed25519 and CoSi

It's rather slow so it's disabled by default.
Use `pytest -m slow_cosi` to run.

trezorlib/tests/unit_tests/test_cosi.py

@@ -0,0 +1,124 @@
+import binascii
+import hashlib
+import pytest
+
+from trezorlib import cosi
+
+# These tests calculate Ed25519 signatures in pure Python.
+# In addition to being Python, this is also DJB's proof-of-concept, unoptimized code.
+# As a result, it is actually very noticeably slow. On a gen8 Core i5, this takes around 40 seconds.
+# To skip the test, run `pytest -m "not slow_cosi"`.
+
+# Therefore, the tests are skipped by default.
+# Run `pytest -m slow_cosi` to explicitly enable.
+
+pytestmark = pytest.mark.slow_cosi
+if "slow_cosi" not in pytest.config.getoption("-m"):
+    pytestmark = pytest.mark.skip("Skipping slow CoSi tests. 'pytest -m slow_cosi' to run.")
+
+
+RFC8032_VECTORS = (
+    (  # test 1
+        # privkey
+        binascii.unhexlify("9d61b19deffd5a60ba844af492ec2cc44449c5697b326919703bac031cae7f60"),
+        # pubkey
+        binascii.unhexlify("d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a"),
+        # message
+        binascii.unhexlify(""),
+        # signature
+        binascii.unhexlify("e5564300c360ac729086e2cc806e828a84877f1eb8e5d974d873e06522490155"
+                           "5fb8821590a33bacc61e39701cf9b46bd25bf5f0595bbe24655141438e7a100b"),
+    ),
+    (  # test 2
+        # privkey
+        binascii.unhexlify("4ccd089b28ff96da9db6c346ec114e0f5b8a319f35aba624da8cf6ed4fb8a6fb"),
+        # pubkey
+        binascii.unhexlify("3d4017c3e843895a92b70aa74d1b7ebc9c982ccf2ec4968cc0cd55f12af4660c"),
+        # message
+        binascii.unhexlify("72"),
+        # signature
+        binascii.unhexlify("92a009a9f0d4cab8720e820b5f642540a2b27b5416503f8fb3762223ebdb69da"
+                           "085ac1e43e15996e458f3613d0f11d8c387b2eaeb4302aeeb00d291612bb0c00"),
+    ),
+    (  # test 3
+        # privkey
+        binascii.unhexlify("c5aa8df43f9f837bedb7442f31dcb7b166d38535076f094b85ce3a2e0b4458f7"),
+        # pubkey
+        binascii.unhexlify("fc51cd8e6218a1a38da47ed00230f0580816ed13ba3303ac5deb911548908025"),
+        # message
+        binascii.unhexlify("af82"),
+        # signature
+        binascii.unhexlify("6291d657deec24024827e69c3abe01a30ce548a284743a445e3680d7db5ac3ac"
+                           "18ff9b538d16f290ae67f760984dc6594a7c15e9716ed28dc027beceea1ec40a"),
+    ),
+    (  # test SHA(abc)
+        # privkey
+        binascii.unhexlify("833fe62409237b9d62ec77587520911e9a759cec1d19755b7da901b96dca3d42"),
+        # pubkey
+        binascii.unhexlify("ec172b93ad5e563bf4932c70e1245034c35467ef2efd4d64ebf819683467e2bf"),
+        # message
+        hashlib.sha512(b"abc").digest(),
+        # signature
+        binascii.unhexlify("dc2a4459e7369633a52b1bf277839a00201009a3efbf3ecb69bea2186c26b589"
+                           "09351fc9ac90b3ecfdfbc7c66431e0303dca179c138ac17ad9bef1177331a704"),
+    ),
+)
+
+COMBINED_KEY = binascii.unhexlify("283967b1c19ff93d2924cdcba95e586547cafef509ea402963ceefe96ccb44f2")
+GLOBAL_COMMIT = binascii.unhexlify("75bd5806c6366e0374a1c6e020c53feb0791d6cc07560d27d8c158f886ecf389")
+
+
+@pytest.mark.parametrize("privkey, pubkey, message, signature",
+                         RFC8032_VECTORS)
+def test_single_eddsa_vector(privkey, pubkey, message, signature):
+    my_pubkey = cosi.pubkey_from_privkey(privkey)
+    assert my_pubkey == pubkey
+    try:
+        cosi.verify(signature, message, pubkey)
+    except ValueError:
+        pytest.fail("Signature does not verify.")
+
+    fake_signature = b'\xf1' + signature[1:]
+    with pytest.raises(ValueError):
+        cosi.verify(fake_signature, message, pubkey)
+
+
+def test_combine_keys():
+    pubkeys = [pubkey for _, pubkey, _, _ in RFC8032_VECTORS]
+    assert cosi.combine_keys(pubkeys) == COMBINED_KEY
+
+    Rs = [cosi.get_nonce(privkey, message)[1] for privkey, _, message, _ in RFC8032_VECTORS]
+    assert cosi.combine_keys(Rs) == GLOBAL_COMMIT
+
+
+@pytest.mark.parametrize("keyset", [
+    (0,),
+    (0, 1),
+    (0, 1, 2),
+    (0, 1, 2, 3),
+    (1, 3),
+])
+def test_cosi_combination(keyset):
+    message = hashlib.sha512(b"You all have to sign this.").digest()
+    selection = [RFC8032_VECTORS[i] for i in keyset]
+
+    # zip(*iterable) turns a list of tuples to a tuple of lists
+    privkeys, pubkeys, _, _ = zip(*selection)
+    nonce_pairs = [cosi.get_nonce(pk, message) for pk in privkeys]
+    nonces, commits = zip(*nonce_pairs)
+
+    # calculate global pubkey and commitment
+    global_pk = cosi.combine_keys(pubkeys)
+    global_commit = cosi.combine_keys(commits)
+
+    # generate individual signatures
+    signatures = [cosi.sign_with_privkey(message, privkey, global_pk, nonce, global_commit)
+                  for privkey, nonce in zip(privkeys, nonces)]
+
+    # combine signatures
+    global_sig = cosi.combine_sig(global_commit, signatures)
+
+    try:
+        cosi.verify(global_sig, message, global_pk)
+    except ValueError:
+        pytest.fail("Failed to validate global signature")