Auto merge of #90 - str4d:ff, r=ebfull

Use ff crate for traits and impls

Depends on https://github.com/ebfull/ff/pull/1 and https://github.com/ebfull/ff/pull/5

Author: bmerge

Cargo.toml

@@ -3,7 +3,10 @@ name = "pairing"
 
 # Remember to change version string in README.md.
 version = "0.14.2"
-authors = ["Sean Bowe <ewillbefull@gmail.com>"]
+authors = [
+    "Sean Bowe <ewillbefull@gmail.com>",
+    "Jack Grigg <jack@z.cash>",
+]
 license = "MIT/Apache-2.0"
 
 description = "Pairing-friendly elliptic curve library"
@@ -14,10 +17,9 @@ repository = "https://github.com/ebfull/pairing"
 [dependencies]
 rand = "0.4"
 byteorder = "1"
-clippy = { version = "0.0.200", optional = true }
+ff = { version = "0.4", features = ["derive"] }
 
 [features]
 unstable-features = ["expose-arith"]
 expose-arith = []
-u128-support = []
 default = []

README.md

@@ -6,14 +6,6 @@ This is a Rust crate for using pairing-friendly elliptic curves. Currently, only
 
 Bring the `pairing` crate into your project just as you normally would.
 
-If you're using a supported platform and the nightly Rust compiler, you can enable the `u128-support` feature for faster arithmetic.
-
-```toml
-[dependencies.pairing]
-version = "0.14"
-features = ["u128-support"]
-```
-
 ## Security Warnings
 
 This library does not make any guarantees about constant-time operations, memory access patterns, or resistance to side-channel attacks.

benches/bls12_381/fq.rs

@@ -1,7 +1,7 @@
 use rand::{Rand, SeedableRng, XorShiftRng};
 
+use ff::{Field, PrimeField, PrimeFieldRepr, SqrtField};
 use pairing::bls12_381::*;
-use pairing::{Field, PrimeField, PrimeFieldRepr, SqrtField};
 
 #[bench]
 fn bench_fq_repr_add_nocarry(b: &mut ::test::Bencher) {

benches/bls12_381/fq12.rs

@@ -1,7 +1,7 @@
 use rand::{Rand, SeedableRng, XorShiftRng};
 
+use ff::Field;
 use pairing::bls12_381::*;
-use pairing::Field;
 
 #[bench]
 fn bench_fq12_add_assign(b: &mut ::test::Bencher) {

benches/bls12_381/fq2.rs

@@ -1,7 +1,7 @@
 use rand::{Rand, SeedableRng, XorShiftRng};
 
+use ff::{Field, SqrtField};
 use pairing::bls12_381::*;
-use pairing::{Field, SqrtField};
 
 #[bench]
 fn bench_fq2_add_assign(b: &mut ::test::Bencher) {

benches/bls12_381/fr.rs

@@ -1,7 +1,7 @@
 use rand::{Rand, SeedableRng, XorShiftRng};
 
+use ff::{Field, PrimeField, PrimeFieldRepr, SqrtField};
 use pairing::bls12_381::*;
-use pairing::{Field, PrimeField, PrimeFieldRepr, SqrtField};
 
 #[bench]
 fn bench_fr_repr_add_nocarry(b: &mut ::test::Bencher) {

benches/pairing_benches.rs

@@ -1,5 +1,6 @@
 #![feature(test)]
 
+extern crate ff;
 extern crate pairing;
 extern crate rand;
 extern crate test;

src/bls12_381/ec.rs

@@ -623,12 +623,10 @@ macro_rules! curve_impl {
 pub mod g1 {
     use super::super::{Bls12, Fq, Fq12, FqRepr, Fr, FrRepr};
     use super::g2::G2Affine;
+    use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr, SqrtField};
     use rand::{Rand, Rng};
     use std::fmt;
-    use {
-        BitIterator, CurveAffine, CurveProjective, EncodedPoint, Engine, Field, GroupDecodingError,
-        PrimeField, PrimeFieldRepr, SqrtField,
-    };
+    use {CurveAffine, CurveProjective, EncodedPoint, Engine, GroupDecodingError};
 
     curve_impl!(
         "G1",
@@ -1270,12 +1268,10 @@ pub mod g1 {
 pub mod g2 {
     use super::super::{Bls12, Fq, Fq12, Fq2, FqRepr, Fr, FrRepr};
     use super::g1::G1Affine;
+    use ff::{BitIterator, Field, PrimeField, PrimeFieldRepr, SqrtField};
     use rand::{Rand, Rng};
     use std::fmt;
-    use {
-        BitIterator, CurveAffine, CurveProjective, EncodedPoint, Engine, Field, GroupDecodingError,
-        PrimeField, PrimeFieldRepr, SqrtField,
-    };
+    use {CurveAffine, CurveProjective, EncodedPoint, Engine, GroupDecodingError};
 
     curve_impl!(
         "G2",