bignp256 0.14.0-rc.10

Pure Rust implementation of the Bign P-256 (a.k.a. bign-curve256v1) elliptic curve as defined in STB 34.101.45-2013, with general purpose curve arithmetic
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#![no_std]
#![cfg_attr(docsrs, feature(doc_cfg))]
#![doc = include_str!("../README.md")]
#![doc(
    html_logo_url = "https://raw.githubusercontent.com/RustCrypto/meta/master/logo.svg",
    html_favicon_url = "https://raw.githubusercontent.com/RustCrypto/meta/master/logo.svg"
)]
#![forbid(unsafe_code)]
#![warn(
    clippy::mod_module_files,
    clippy::cast_lossless,
    clippy::cast_possible_truncation,
    clippy::cast_possible_wrap,
    clippy::cast_precision_loss,
    clippy::cast_sign_loss,
    clippy::checked_conversions,
    clippy::implicit_saturating_sub,
    clippy::arithmetic_side_effects,
    clippy::panic,
    clippy::panic_in_result_fn,
    clippy::unwrap_used,
    missing_docs,
    rust_2018_idioms,
    unused_lifetimes,
    unused_qualifications
)]

#[cfg(feature = "alloc")]
#[allow(unused_extern_crates)]
extern crate alloc;

pub use elliptic_curve::{self, bigint::U256};
use elliptic_curve::{
    Error, FieldBytesEncoding,
    bigint::{ArrayEncoding, Odd},
    consts::U32,
};

#[cfg(feature = "arithmetic")]
pub use {
    arithmetic::{AffinePoint, ProjectivePoint, scalar::Scalar},
    public_key::PublicKey,
    secret_key::SecretKey,
};

/// Bign256 result type
pub type Result<T> = core::result::Result<T, Error>;

#[cfg(feature = "arithmetic")]
pub mod arithmetic;

#[cfg(any(feature = "test-vectors", test))]
pub mod test_vectors;

#[cfg(feature = "ecdh")]
pub mod ecdh;
#[cfg(feature = "ecdsa")]
pub mod ecdsa;
#[cfg(feature = "arithmetic")]
pub mod public_key;
#[cfg(feature = "arithmetic")]
pub mod secret_key;

#[cfg(feature = "pkcs8")]
#[allow(dead_code)]
const ALGORITHM_OID: pkcs8::ObjectIdentifier =
    pkcs8::ObjectIdentifier::new_unwrap("1.2.112.0.2.0.34.101.45.2.1");

#[cfg(feature = "ecdsa")]
type Hash = digest::Output<belt_hash::BeltHash>;

/// Order of BIGN P-256's elliptic curve group (i.e. scalar modulus) in hexadecimal.
const ORDER_HEX: &str = "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD95C8ED60DFB4DFC7E5ABF99263D6607";

/// BIGN P-256 elliptic curve.
///
/// This curve is also known as bign-curve256v1
/// and is specified in [STB 34.101.45-2013]:
/// Recommendations for Discrete Logarithm-based Cryptography:
/// Elliptic Curve Domain Parameters.
///
///
/// Its equation is `y² = x³ + ax + b` over a ~256-bit prime field.
///
/// ```text
/// a = 115792089237316195423570985008687907853269984665640564039457584007913129639744
/// b = 54189945433829174764701416670523239872420438478408031144987871676190519198705
/// ```
///
/// [STB 34.101.45-2013]: https://apmi.bsu.by/assets/files/std/bign-spec294.pdf
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, PartialOrd, Ord)]
pub struct BignP256;

impl elliptic_curve::Curve for BignP256 {
    /// 256-bit integer type used for internally representing field elements.
    type FieldBytesSize = U32;
    type Uint = U256;

    /// Order of BIGN P-256's elliptic curve group (i.e. scalar modulus).
    const ORDER: Odd<U256> = Odd::<U256>::from_be_hex(ORDER_HEX);
}

impl elliptic_curve::PrimeCurve for BignP256 {}

impl elliptic_curve::point::PointCompression for BignP256 {
    /// BIGN P-256 points are typically uncompressed.
    const COMPRESS_POINTS: bool = false;
}

impl elliptic_curve::point::PointCompaction for BignP256 {
    /// BIGN P-256 points are typically uncompressed.
    const COMPACT_POINTS: bool = false;
}

#[cfg(feature = "pkcs8")]
impl pkcs8::AssociatedOid for BignP256 {
    const OID: pkcs8::ObjectIdentifier =
        pkcs8::ObjectIdentifier::new_unwrap("1.2.112.0.2.0.34.101.45.3.1");
}

/// BIGN P-256 field element serialized as bytes.
///
/// Byte array containing a serialized field element value (base field or scalar).
pub type FieldBytes = elliptic_curve::FieldBytes<BignP256>;

/// SEC1 encoded point.
pub type Sec1Point = elliptic_curve::sec1::Sec1Point<BignP256>;

impl FieldBytesEncoding<BignP256> for U256 {
    fn decode_field_bytes(field_bytes: &FieldBytes) -> Self {
        U256::from_le_byte_array(*field_bytes)
    }

    fn encode_field_bytes(&self) -> FieldBytes {
        self.to_le_byte_array()
    }
}

/// Non-zero scalar field element.
#[cfg(feature = "arithmetic")]
pub type NonZeroScalar = elliptic_curve::NonZeroScalar<BignP256>;

/// Generic scalar type with primitive functionality.#
#[cfg(feature = "arithmetic")]
pub type ScalarValue = elliptic_curve::ScalarValue<BignP256>;