83 lines
2.3 KiB
Markdown
83 lines
2.3 KiB
Markdown
# ff
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`ff` is a finite field library written in pure Rust, with no `unsafe{}` code.
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## RFC process
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This crate follows the [zkcrypto RFC process](https://zkcrypto.github.io/rfcs/).
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If you want to propose "substantial" changes to this crate (in particular to the
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`ff` traits), please [create an RFC](https://github.com/zkcrypto/rfcs) for wider
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discussion.
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## Disclaimers
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* This library does not provide constant-time guarantees. The traits enable downstream
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users to expose constant-time logic, but `#[derive(PrimeField)]` in particular does not
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generate constant-time code (even for trait methods that return constant-time-compatible
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values).
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## Usage
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Add the `ff` crate to your `Cargo.toml`:
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```toml
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[dependencies]
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ff = "0.13"
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```
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The `ff` crate contains the `Field` and `PrimeField` traits.
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See the **[documentation](https://docs.rs/ff/)** for more.
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### `#![derive(PrimeField)]`
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If you need an implementation of a prime field, this library also provides a procedural
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macro that will expand into an efficient implementation of a prime field when supplied
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with the modulus. `PrimeFieldGenerator` must be an element of Fp of p-1 order, that is
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also quadratic nonresidue.
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First, enable the `derive` crate feature:
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```toml
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[dependencies]
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ff = { version = "0.13", features = ["derive"] }
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```
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And then use the macro like so:
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```rust
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#[macro_use]
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extern crate ff;
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#[derive(PrimeField)]
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#[PrimeFieldModulus = "52435875175126190479447740508185965837690552500527637822603658699938581184513"]
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#[PrimeFieldGenerator = "7"]
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#[PrimeFieldReprEndianness = "little"]
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struct Fp([u64; 4]);
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```
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And that's it! `Fp` now implements `Field` and `PrimeField`.
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## Minimum Supported Rust Version
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Requires Rust **1.56** or higher.
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Minimum supported Rust version can be changed in the future, but it will be done with a
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minor version bump.
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## License
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Licensed under either of
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* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
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http://www.apache.org/licenses/LICENSE-2.0)
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* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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at your option.
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### Contribution
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Unless you explicitly state otherwise, any contribution intentionally
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submitted for inclusion in the work by you, as defined in the Apache-2.0
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license, shall be dual licensed as above, without any additional terms or
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conditions.
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