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Move the Scalar constructor documentation to the module level.

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Isis Lovecruft 2018-07-04 21:29:36 +00:00
parent 1b52b4b7b7
commit f4669c8b4d
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1 changed files with 22 additions and 22 deletions
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44
src/scalar.rs
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@ -11,6 +11,28 @@
// - Brian Smith <brian@briansmith.org> // - Brian Smith <brian@briansmith.org>
//! Arithmetic on scalars (integers mod the group order). //! Arithmetic on scalars (integers mod the group order).
//!
//! Both the Ristretto group and the Ed25519 basepoint have prime order
//! \\( \ell = 2\^{252} + 27742317777372353535851937790883648493 \\).
//!
//! This code is intended to be useful with both the Ristretto group
//! (where everything is done modulo \\( \ell \\)), and the X/Ed25519
//! setting, which mandates specific bit-twiddles that are not
//! well-defined modulo \\( \ell \\).
//!
//! To create a `Scalar` from a supposedly canonical encoding, use
//! `Scalar::from_canonical_bytes`.
//!
//! To create a `Scalar` by reducing a \\(256\\)-bit integer mod \\( \ell \\),
//! use `Scalar::from_bytes_mod_order`.
//!
//! To create a `Scalar` by reducing a \\(512\\)-bit integer mod \\( \ell \\),
//! use `Scalar::from_bytes_mod_order_wide`.
//!
//! To create a `Scalar` with a specific bit-pattern (e.g., for
//! compatibility with X25519 "clamping"), use `Scalar::from_bits`.
//!
//! All arithmetic on `Scalars` is done modulo \\( \ell \\).
use core::fmt::Debug; use core::fmt::Debug;
use core::ops::Neg; use core::ops::Neg;
@ -51,28 +73,6 @@ type UnpackedScalar = backend::u32::scalar::Scalar32;
/// The `Scalar` struct holds an integer \\(s < 2\^{255} \\) which /// The `Scalar` struct holds an integer \\(s < 2\^{255} \\) which
/// represents an element of \\(\mathbb Z / \ell\\). /// represents an element of \\(\mathbb Z / \ell\\).
///
/// Both the Ristretto group and the Ed25519 basepoint have prime order
/// \\( \ell = 2\^{252} + 27742317777372353535851937790883648493 \\).
///
/// The code is intended to be useful with both the Ristretto group
/// (where everything is done modulo \\( \ell \\)), and the X/Ed25519
/// setting, which mandates specific bit-twiddles that are not
/// well-defined modulo \\( \ell \\).
///
/// To create a `Scalar` from a supposedly canonical encoding, use
/// `Scalar::from_canonical_bytes`.
///
/// To create a `Scalar` by reducing a \\(256\\)-bit integer mod \\( \ell \\),
/// use `Scalar::from_bytes_mod_order`.
///
/// To create a `Scalar` by reducing a \\(512\\)-bit integer mod \\( \ell \\),
/// use `Scalar::from_bytes_mod_order_wide`.
///
/// To create a `Scalar` with a specific bit-pattern (e.g., for
/// compatibility with X25519 "clamping"), use `Scalar::from_bits`.
///
/// All arithmetic on `Scalars` is done modulo \\( \ell \\).
#[derive(Copy, Clone)] #[derive(Copy, Clone)]
pub struct Scalar { pub struct Scalar {
/// `bytes` is a little-endian byte encoding of an integer representing a scalar modulo the group order. /// `bytes` is a little-endian byte encoding of an integer representing a scalar modulo the group order.