Fix missing features found by Rust 1.80

[tarcieri]

Some crates were defining features but not using them:

• bign256: bits, serde, test-vectors
• p521: bits
• sm2: bits

In fixing this, I also uncovered that bign256's test vectors are failing.

[tarcieri]

FYI @makavity, these weren't actually running before apparently:

test test_vector_double_generator ... FAILED
test test_vector_repeated_add ... FAILED
test test_vector_repeated_add_mixed ... FAILED
test test_vector_scalar_mult ... FAILED

failures:

---- test_vector_double_generator stdout ----
thread 'test_vector_double_generator' panicked at bign256/tests/projective.rs:17:1:
assertion `left == right` failed
  left: [45, 132, 25, 227, 217, 5, 210, 30, 54, 17, 38, 29, 173, 201, 91, 179, 85, 131, 9, 12, 44, 173, 208, 200, 7, 245, 59, 179, 130, 143, 9, 149]
 right: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- test_vector_repeated_add stdout ----
thread 'test_vector_repeated_add' panicked at bign256/tests/projective.rs:17:1:
assertion `left == right` failed
  left: [45, 132, 25, 227, 217, 5, 210, 30, 54, 17, 38, 29, 173, 201, 91, 179, 85, 131, 9, 12, 44, 173, 208, 200, 7, 245, 59, 179, 130, 143, 9, 149]
 right: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

---- test_vector_repeated_add_mixed stdout ----
thread 'test_vector_repeated_add_mixed' panicked at bign256/tests/projective.rs:17:1:
assertion `left == right` failed
  left: [45, 132, 25, 227, 217, 5, 210, 30, 54, 17, 38, 29, 173, 201, 91, 179, 85, 131, 9, 12, 44, 173, 208, 200, 7, 245, 59, 179, 130, 143, 9, 149]
 right: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

---- test_vector_scalar_mult stdout ----
thread 'test_vector_scalar_mult' panicked at bign256/tests/projective.rs:17:1:
assertion `left == right` failed
  left: [45, 132, 25, 227, 217, 5, 210, 30, 54, 17, 38, 29, 173, 201, 91, 179, 85, 131, 9, 12, 44, 173, 208, 200, 7, 245, 59, 179, 130, 143, 9, 149]
 right: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]


failures:
    test_vector_double_generator
    test_vector_repeated_add
    test_vector_repeated_add_mixed
    test_vector_scalar_mult

[makavity]

I've fixed ADD_TEST_VECTORS, because of test specific.

// k = 1,..,20, p += G
    (
        hex!("0000000000000000000000000000000000000000000000000000000000000000"),
        hex!("6BF7FC3CFB16D69F5CE4C9A351D6835D78913966C408F6521E29CF1804516A93"),
    ),
    ...

But have no idea, how to fix MUL_TEST_VECTORS. Do you have snippet for sagemath, to generate it?

[makavity]

Nvm. Just generated and fixed :)

p = 2**256 - 189
a = 2**256 - 192
b = 0x77CE6C1515F3A8EDD2C13AABE4D8FBBE4CF55069978B9253B22E7D6BD69C03F1
Gx = 0
Gy = 0x6BF7FC3CFB16D69F5CE4C9A351D6835D78913966C408F6521E29CF1804516A93
h = 1

# Create the finite field and the elliptic curve
F = GF(p)
E = EllipticCurve(F, [a, b])

# Define the base point
G = E(Gx, Gy)
n = G.order()

# Generate test vectors
def generate_mul_test_vectors(num_vectors):
    vectors = []
    for _ in range(num_vectors):
        k = ZZ.random_element(1, n)
        P = k * G
        vectors.append((k, P))
    return vectors

# Number of test vectors to generate
num_vectors = 20
test_vectors = generate_mul_test_vectors(num_vectors)

# Print the test vectors in the required format
for k, P in test_vectors:
    k_hex = f"{k:064X}"
    Px_hex = f"{int(P[0]):064X}"
    Py_hex = f"{int(P[1]):064X}"
    print(f'    (')
    print(f'        hex!("{k_hex}"),')
    print(f'        hex!("{Px_hex}"),')
    print(f'        hex!("{Py_hex}"),')
    print(f'    ),')

[makavity]

Fixed in #1065.
Thank you