p521 0.14.0-rc.10

Pure Rust implementation of the NIST P-521 (a.k.a. secp521r1) elliptic curve as defined in SP 800-186
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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::unwrap_used,
    missing_docs,
    rust_2018_idioms,
    unused_lifetimes,
    unused_qualifications
)]

//! ## `serde` support
//!
//! When the `serde` feature of this crate is enabled, `Serialize` and
//! `Deserialize` are impl'd for the following types:
//!
//! - [`AffinePoint`]
//! - [`ProjectivePoint`]
//! - [`Scalar`]
//!
//! Please see type-specific documentation for more information.

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

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

#[cfg(feature = "ecdsa-core")]
pub mod ecdsa;

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

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

#[cfg(feature = "expose-field")]
pub use arithmetic::field::FieldElement;

#[cfg(feature = "hash2curve")]
pub use hash2curve;

pub use elliptic_curve;

#[cfg(feature = "pkcs8")]
pub use elliptic_curve::pkcs8;

use elliptic_curve::{
    FieldBytesEncoding,
    array::Array,
    bigint::{Odd, cpubits},
    consts::{U66, U67},
};

cpubits! {
    32 => { use elliptic_curve::bigint::U544 as Uint; }
    64 => { use elliptic_curve::bigint::U576 as Uint; }
}

/// Order of NIST P-521's elliptic curve group (i.e. scalar modulus) in hexadecimal.
const ORDER_HEX: &str = {
    cpubits! {
        32 => {
            "000001fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa51868783bf2f966b7fcc0148f709a5d03bb5c9b8899c47aebb6fb71e91386409"
        }
        64 => {
            "00000000000001fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffa51868783bf2f966b7fcc0148f709a5d03bb5c9b8899c47aebb6fb71e91386409"
        }
    }
};

/// NIST P-521 elliptic curve.
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, PartialOrd, Ord)]
pub struct NistP521;

impl elliptic_curve::Curve for NistP521 {
    /// 66-byte serialized field elements.
    type FieldBytesSize = U66;

    /// 521-bit integer type used for internally representing field elements.
    type Uint = Uint;

    /// Order of NIST P-521's elliptic curve group (i.e. scalar modulus).
    const ORDER: Odd<Uint> = Odd::<Uint>::from_be_hex(ORDER_HEX);
}

impl elliptic_curve::PrimeCurve for NistP521 {}

impl elliptic_curve::point::PointCompression for NistP521 {
    /// NIST P-521 points are typically uncompressed.
    const COMPRESS_POINTS: bool = false;
}

impl elliptic_curve::point::PointCompaction for NistP521 {
    /// NIST P-521 points are typically uncompacted.
    const COMPACT_POINTS: bool = false;
}

#[cfg(feature = "pkcs8")]
impl pkcs8::AssociatedOid for NistP521 {
    const OID: pkcs8::ObjectIdentifier = pkcs8::ObjectIdentifier::new_unwrap("1.3.132.0.35");
}

/// Compressed SEC1-encoded NIST P-521 curve point.
pub type CompressedPoint = Array<u8, U67>;

/// NIST P-521 SEC1 encoded point.
pub type Sec1Point = elliptic_curve::sec1::Sec1Point<NistP521>;

/// NIST P-521 field element serialized as bytes.
///
/// Byte array containing a serialized field element value (base field or
/// scalar).
pub type FieldBytes = elliptic_curve::FieldBytes<NistP521>;

impl FieldBytesEncoding<NistP521> for Uint {}

/// Non-zero NIST P-521 scalar field element.
#[cfg(feature = "arithmetic")]
pub type NonZeroScalar = elliptic_curve::NonZeroScalar<NistP521>;

/// NIST P-521 public key.
#[cfg(feature = "arithmetic")]
pub type PublicKey = elliptic_curve::PublicKey<NistP521>;

/// NIST P-521 secret key.
pub type SecretKey = elliptic_curve::SecretKey<NistP521>;

#[cfg(feature = "oprf")]
impl hash2curve::OprfParameters for NistP521 {
    /// See <https://www.rfc-editor.org/rfc/rfc9497.html#section-4.5-1>.
    const ID: &'static [u8] = b"P521-SHA512";
}

#[cfg(test)]
mod tests {
    use super::{CompressedPoint, NistP521};
    use core::mem::size_of;
    use elliptic_curve::sec1::CompressedPoint as Sec1Compressed;

    #[test]
    fn compressed_point_size_matches_sec1() {
        assert_eq!(size_of::<CompressedPoint>(), 67);
        assert_eq!(
            size_of::<CompressedPoint>(),
            size_of::<Sec1Compressed<NistP521>>(),
        );
    }
}