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The audit recommends checking failure cases for from_bytes, from_bytes_unechecked, and from_repr. This isn't feasible. from_bytes is allowed to have non-canonical values. [0xff; 32] may accordingly be a valid point for non-SEC1-encoded curves. from_bytes_unchecked doesn't have a defined failure mode, and by name, unchecked, shouldn't necessarily fail. The audit acknowledges the tests should test for whatever result is 'appropriate', yet any result which isn't a failure on a valid element is appropriate. from_repr must be canonical, yet for a binary field of 2^n where n % 8 == 0, a [0xff; n / 8] repr would be valid.
39 lines
1.2 KiB
Rust
39 lines
1.2 KiB
Rust
use zeroize::Zeroize;
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use crypto_bigint::{U512, U1024};
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pub use crate::field;
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#[derive(Clone, Copy, PartialEq, Eq, Default, Debug, Zeroize)]
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pub struct Scalar(pub(crate) U512);
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// 2**446 - 13818066809895115352007386748515426880336692474882178609894547503885
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pub const MODULUS: Scalar = Scalar(U512::from_be_hex(concat!(
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"00000000000000",
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"00",
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"3fffffffffffffffffffffffffffffffffffffffffffffffffffffff",
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"7cca23e9c44edb49aed63690216cc2728dc58f552378c292ab5844f3",
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)));
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const WIDE_MODULUS: U1024 = U1024::from_be_hex(concat!(
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"0000000000000000000000000000000000000000000000000000000000000000",
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"0000000000000000000000000000000000000000000000000000000000000000",
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"00000000000000",
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"00",
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"3fffffffffffffffffffffffffffffffffffffffffffffffffffffff",
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"7cca23e9c44edb49aed63690216cc2728dc58f552378c292ab5844f3",
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));
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field!(Scalar, MODULUS, WIDE_MODULUS, 446);
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impl Scalar {
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pub fn wide_reduce(bytes: [u8; 114]) -> Scalar {
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Scalar(reduce(U1024::from_le_slice(&[bytes.as_ref(), &[0; 14]].concat())))
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}
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}
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#[test]
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fn test_scalar_field() {
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// TODO: Move to test_prime_field_bits once the impl is finished
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ff_group_tests::prime_field::test_prime_field::<_, Scalar>(&mut rand_core::OsRng);
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}
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