librustzcash/ff
Jack Grigg 56999d0f73
Constant-time field inversion in ff_derive using Field::pow_vartime
This is around 2.5-3x slower than the non-constant-time inversion. We
can regain some of this speed later by dynamically generating addition
chains.
2019-12-19 12:25:39 -06:00
..
ff_derive Constant-time field inversion in ff_derive using Field::pow_vartime 2019-12-19 12:25:39 -06:00
src no_std support for ff crate 2019-12-14 12:55:34 +00:00
.gitignore Add 'ff/' from commit '661558e0c8a5e02e08dac6530d39b2e38919aa04' 2019-01-06 09:37:22 +00:00
Cargo.toml no_std support for ff crate 2019-12-14 12:55:34 +00:00
LICENSE-APACHE Add 'ff/' from commit '661558e0c8a5e02e08dac6530d39b2e38919aa04' 2019-01-06 09:37:22 +00:00
LICENSE-MIT Add 'ff/' from commit '661558e0c8a5e02e08dac6530d39b2e38919aa04' 2019-01-06 09:37:22 +00:00
README.md Update READMEs 2019-09-24 14:23:55 +01:00

README.md

ff

ff is a finite field library written in pure Rust, with no unsafe{} code.

Disclaimers

  • This library does not provide constant-time guarantees.

Usage

Add the ff crate to your Cargo.toml:

[dependencies]
ff = "0.4"

The ff crate contains Field, PrimeField, PrimeFieldRepr and SqrtField traits. See the documentation for more.

#![derive(PrimeField)]

If you need an implementation of a prime field, this library also provides a procedural macro that will expand into an efficient implementation of a prime field when supplied with the modulus. PrimeFieldGenerator must be an element of Fp of p-1 order, that is also quadratic nonresidue.

First, enable the derive crate feature:

[dependencies]
ff = { version = "0.4", features = ["derive"] }

And then use the macro like so:

extern crate rand;
#[macro_use]
extern crate ff;

#[derive(PrimeField)]
#[PrimeFieldModulus = "52435875175126190479447740508185965837690552500527637822603658699938581184513"]
#[PrimeFieldGenerator = "7"]
struct Fp(FpRepr);

And that's it! Fp now implements Field and PrimeField. Fp will also implement SqrtField if supported. The library implements FpRepr itself and derives PrimeFieldRepr for it.

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.