Add support for 448-bit integers and fields. (#261)

These are needed for the Pluto and Eris curves (https://github.com/daira/pluto-eris).

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

Co-authored-by: Weikeng Chen <w.k@berkeley.edu>

ff/src/biginteger/mod.rs

@@ -34,6 +34,7 @@ bigint_impl!(BigInteger128, 2);
 bigint_impl!(BigInteger256, 4);
 bigint_impl!(BigInteger320, 5);
 bigint_impl!(BigInteger384, 6);
+bigint_impl!(BigInteger448, 7);
 bigint_impl!(BigInteger768, 12);
 bigint_impl!(BigInteger832, 13);
 

ff/src/biginteger/tests.rs

@@ -89,6 +89,12 @@ fn test_biginteger384() {
     test_biginteger(B::new([0u64; 6]));
 }
 
+#[test]
+fn test_biginteger448() {
+    use crate::biginteger::BigInteger448 as B;
+    test_biginteger(B::new([0u64; 7]));
+}
+
 #[test]
 fn test_biginteger768() {
     use crate::biginteger::BigInteger768 as B;

ff/src/fields/mod.rs

@@ -545,13 +545,15 @@ impl<Slice: AsRef<[u64]>> Iterator for BitIteratorLE<Slice> {
 }
 
 use crate::biginteger::{
-    BigInteger256, BigInteger320, BigInteger384, BigInteger64, BigInteger768, BigInteger832,
+    BigInteger256, BigInteger320, BigInteger384, BigInteger448, BigInteger64, BigInteger768,
+    BigInteger832,
 };
 
 impl_field_bigint_conv!(Fp64, BigInteger64, Fp64Parameters);
 impl_field_bigint_conv!(Fp256, BigInteger256, Fp256Parameters);
 impl_field_bigint_conv!(Fp320, BigInteger320, Fp320Parameters);
 impl_field_bigint_conv!(Fp384, BigInteger384, Fp384Parameters);
+impl_field_bigint_conv!(Fp448, BigInteger448, Fp448Parameters);
 impl_field_bigint_conv!(Fp768, BigInteger768, Fp768Parameters);
 impl_field_bigint_conv!(Fp832, BigInteger832, Fp832Parameters);
 

ff/src/fields/models/mod.rs

@@ -11,7 +11,7 @@ use num_traits::{One, Zero};
 use crate::{
     biginteger::{
         arithmetic as fa, BigInteger as _BigInteger, BigInteger256, BigInteger320, BigInteger384,
-        BigInteger64, BigInteger768, BigInteger832,
+        BigInteger448, BigInteger64, BigInteger768, BigInteger832,
     },
     bytes::{FromBytes, ToBytes},
     fields::{FftField, Field, FpParameters, LegendreSymbol, PrimeField, SquareRootField},
@@ -22,6 +22,7 @@ impl_Fp!(Fp64, Fp64Parameters, BigInteger64, BigInteger64, 1);
 impl_Fp!(Fp256, Fp256Parameters, BigInteger256, BigInteger256, 4);
 impl_Fp!(Fp320, Fp320Parameters, BigInteger320, BigInteger320, 5);
 impl_Fp!(Fp384, Fp384Parameters, BigInteger384, BigInteger384, 6);
+impl_Fp!(Fp448, Fp448Parameters, BigInteger448, BigInteger448, 7);
 impl_Fp!(Fp768, Fp768Parameters, BigInteger768, BigInteger768, 12);
 impl_Fp!(Fp832, Fp832Parameters, BigInteger832, BigInteger832, 13);