# fff
> Fork of the great [ff](https://github.com/zkcrypto/ff) library.
`fff` is a finite field library written in Rust.
## Disclaimers
* This library does not provide constant-time guarantees.
The `fff` crate contains `Field`, `PrimeField`, `PrimeFieldRepr` and `SqrtField` traits.
See the **[documentation](https://docs.rs/fff/)** 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:
```toml
[dependencies]
fff = { version = "0.2", features = ["derive"] }
```
And then use the macro like so:
```rust
extern crate rand;
#[macro_use]
extern crate fff;
#[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
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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.