test_modular_comparison()

Documentation for tests/osaka/eip7951_p256verify_precompiles/test_p256verify.py::test_modular_comparison@v5.0.0.

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="modular_comparison_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=[""])
@pytest.mark.eip_checklist("precompile/test/inputs/valid")
@pytest.mark.eip_checklist("precompile/test/inputs/invalid/crypto")
def test_modular_comparison(state_test: StateTestFiller, pre: Alloc, post: dict, tx: Transaction):
    """
    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--modular_comparison_x_coordinate_exceeds_n	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 00000000000000000000000000000000 4319055358e8617b0c46353d039cdaab ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc63254e 0ad99500288d466940031d72a9f5445a 4d43784640855bf0a69874d2de5fe103 c5011e6ef2c42dcd50d5d3d29f99ae6e ba2c80c9244f4c5422f0979ff0c3ba5e	00000000000000000000000000000000 00000000000000000000000000000001
...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--modular_comparison_x_coordinate_exceeds_n	256	bb5a52f42f9c9261ed4361f59422a1e3 0036e7c32b270c8807a419feca605023 00000000000000000000000000000000 4319055358e8617b0c46353d039cdaab ffffffff00000000ffffffffffffffff bce6faada7179e84f3b9cac2fc63254e 0ad99500288d466940031d72a9f5445a 4d43784640855bf0a69874d2de5fe103 c5011e6ef2c42dcd50d5d3d29f99ae6e ba2c80c9244f4c5422f0979ff0c3ba5e	00000000000000000000000000000000 00000000000000000000000000000001
...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