test_modular_comparison()

Documentation for tests/osaka/eip7951_p256verify_precompiles/test_p256verify.py::test_modular_comparison@88e9fb8f.

Generate fixtures for these test cases for Osaka with:

fill -v tests/osaka/eip7951_p256verify_precompiles/test_p256verify.py::test_modular_comparison --fork Osaka

Test the modular comparison condition for secp256r1 precompile.

This tests that when the x-coordinate of R' exceeds the curve order N, the verification should use modular arithmetic: r' ≡ r (mod N) instead of direct equality r' == r.

Source code in tests/osaka/eip7951_p256verify_precompiles/test_p256verify.py

@pytest.mark.parametrize(
    "input_data,expected_output",
    [
        # Test case where computed x-coordinate exceeds curve order N
        # This tests the modular comparison: r' ≡ r (mod N)
        pytest.param(
            Spec.H0
            # R: A value that when used in ECDSA verification produces an
            # x-coordinate > N
            + R(0x000000000000000000000000000000004319055358E8617B0C46353D039CDAAB)
            + S(0xFFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC63254E)
            # X, Y: Public key coordinates that will produce x-coordinate > N
            # during verification
            + X(0x0AD99500288D466940031D72A9F5445A4D43784640855BF0A69874D2DE5FE103)
            + Y(0xC5011E6EF2C42DCD50D5D3D29F99AE6EBA2C80C9244F4C5422F0979FF0C3BA5E),
            Spec.SUCCESS_RETURN_VALUE,
            id="x_coordinate_exceeds_n",
        ),
        pytest.param(
            Spec.H1 + Spec.R1 + Spec.S1 + Spec.X1 + Spec.Y1,
            Spec.SUCCESS_RETURN_VALUE,
            id="x_coordinate_exceeds_n_v2",
        ),
        # Test cases where compute x-coordinate exceeds curve order N,
        # but the signature is invalid.
        # This is a modification of the above test by taking -h, -r, -s
        # what gives the same u1 and u2 and in the result the same point R.
        pytest.param(
            H(Spec.N - Spec.H1.value)
            + R(Spec.N - Spec.R1.value)
            + S(Spec.N - Spec.S1.value)
            + Spec.X1
            + Spec.Y1,
            Spec.INVALID_RETURN_VALUE,
            id="invalid_x_coordinate_exceeds_n",
        ),
        pytest.param(
            Spec.H0
            + R(Spec.N + 1)  # R = N + 1 ≡ 1 (mod N)
            + Spec.S0
            + Spec.X0
            + Spec.Y0,
            Spec.INVALID_RETURN_VALUE,  # Should fail because R = 1 is not a
            # valid signature
            id="r_equals_n_plus_one",
        ),
        pytest.param(
            Spec.H0
            + R(Spec.N + 2)  # R = N + 2 ≡ 2 (mod N)
            + Spec.S0
            + Spec.X0
            + Spec.Y0,
            Spec.INVALID_RETURN_VALUE,  # Should fail because R = 2 is not a
            # valid signature
            id="r_equals_n_plus_two",
        ),
    ],
)
@pytest.mark.parametrize("precompile_address", [Spec.P256VERIFY], ids=[""])
@EIPChecklist.Precompile.Test.Inputs.Valid()
@EIPChecklist.Precompile.Test.Inputs.Invalid.Crypto()
def test_modular_comparison(
    state_test: StateTestFiller, pre: Alloc, post: dict, tx: Transaction
) -> None:
    """
    Test the modular comparison condition for secp256r1 precompile.

    This tests that when the x-coordinate of R' exceeds the curve order N, the
    verification should use modular arithmetic: r' ≡ r (mod N) instead of
    direct equality r' == r.
    """
    state_test(env=Environment(), pre=pre, post=post, tx=tx)

Parametrized Test Cases

The interactive table below is also available as a standalone page.

Fork All Forks Osaka

Fixture Type All Fixture Types state_test blockchain_test

Test ID (Abbreviated)	precompile_address	input_data	expected_output
...fork_Osaka-state_test--x_coordinate_exceeds_n	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 00000000000000000000000000000000 4319055358e8617b0c46353d039cdaab ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc63254e 0ad99500288d466940031d72a9f5445a 4d43784640855bf0a69874d2de5fe103 c5011e6ef2c42dcd50d5d3d29f99ae6e ba2c80c9244f4c5422f0979ff0c3ba5e	00000000000000000000000000000000 00000000000000000000000000000001
...fork_Osaka-state_test--x_coordinate_exceeds_n_v2	256	532eaabd9574880dbf76b9b8cc00832c 20a6ec113d682299550d7a6e0f345e25 00000000000000000000000000000000 4319055358e8617b0c46353d039cdaab ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc63254e d705d16f80987e2d9b1a6957d29ce22f ebf7d10fa515153182415c8361baaca4 b1fc105ee5ce80d514ec1238beae2037 a6f83625593620d460819e8682160926	00000000000000000000000000000000 00000000000000000000000000000001
...fork_Osaka-state_test--invalid_x_coordinate_exceeds_n	256	acd155416a8b77f34089464733ff7cd3 9c400e9c69af7beb9eac5054ed2ec72c ffffffff00000000ffffffffffffffff 79cdf55a4e2f3d09e7739585f8c64aa6 00000000000000000000000000000000 00000000000000000000000000000003 d705d16f80987e2d9b1a6957d29ce22f ebf7d10fa515153182415c8361baaca4 b1fc105ee5ce80d514ec1238beae2037 a6f83625593620d460819e8682160926
...fork_Osaka-state_test--r_equals_n_plus_one	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc632552 4cd60b855d442f5b3c7b11eb6c4e0ae7 525fe710fab9aa7c77a67f79e6fadd76 2927b10512bae3eddcfe467828128bad 2903269919f7086069c8c4df6c732838 c7787964eaac00e5921fb1498a60f460 6766b3d9685001558d1a974e7341513e
...fork_Osaka-state_test--r_equals_n_plus_two	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc632553 4cd60b855d442f5b3c7b11eb6c4e0ae7 525fe710fab9aa7c77a67f79e6fadd76 2927b10512bae3eddcfe467828128bad 2903269919f7086069c8c4df6c732838 c7787964eaac00e5921fb1498a60f460 6766b3d9685001558d1a974e7341513e
...fork_Osaka-blockchain_test_from_state_test--x_coordinate_exceeds_n	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 00000000000000000000000000000000 4319055358e8617b0c46353d039cdaab ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc63254e 0ad99500288d466940031d72a9f5445a 4d43784640855bf0a69874d2de5fe103 c5011e6ef2c42dcd50d5d3d29f99ae6e ba2c80c9244f4c5422f0979ff0c3ba5e	00000000000000000000000000000000 00000000000000000000000000000001
...fork_Osaka-blockchain_test_from_state_test--x_coordinate_exceeds_n_v2	256	532eaabd9574880dbf76b9b8cc00832c 20a6ec113d682299550d7a6e0f345e25 00000000000000000000000000000000 4319055358e8617b0c46353d039cdaab ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc63254e d705d16f80987e2d9b1a6957d29ce22f ebf7d10fa515153182415c8361baaca4 b1fc105ee5ce80d514ec1238beae2037 a6f83625593620d460819e8682160926	00000000000000000000000000000000 00000000000000000000000000000001
...fork_Osaka-blockchain_test_from_state_test--invalid_x_coordinate_exceeds_n	256	acd155416a8b77f34089464733ff7cd3 9c400e9c69af7beb9eac5054ed2ec72c ffffffff00000000ffffffffffffffff 79cdf55a4e2f3d09e7739585f8c64aa6 00000000000000000000000000000000 00000000000000000000000000000003 d705d16f80987e2d9b1a6957d29ce22f ebf7d10fa515153182415c8361baaca4 b1fc105ee5ce80d514ec1238beae2037 a6f83625593620d460819e8682160926
...fork_Osaka-blockchain_test_from_state_test--r_equals_n_plus_one	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc632552 4cd60b855d442f5b3c7b11eb6c4e0ae7 525fe710fab9aa7c77a67f79e6fadd76 2927b10512bae3eddcfe467828128bad 2903269919f7086069c8c4df6c732838 c7787964eaac00e5921fb1498a60f460 6766b3d9685001558d1a974e7341513e
...fork_Osaka-blockchain_test_from_state_test--r_equals_n_plus_two	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc632553 4cd60b855d442f5b3c7b11eb6c4e0ae7 525fe710fab9aa7c77a67f79e6fadd76 2927b10512bae3eddcfe467828128bad 2903269919f7086069c8c4df6c732838 c7787964eaac00e5921fb1498a60f460 6766b3d9685001558d1a974e7341513e