Remove CipherSuite (#20)

* Remove `Hash`

* Remove `CipherSuite`

* Remove single field `struct`s

src/group/p256.rs

@@ -15,9 +15,9 @@
 
 use super::Group;
 use crate::errors::InternalError;
-use crate::hash::Hash;
 use core::ops::{Add, Div, Mul, Neg};
 use core::str::FromStr;
+use digest::{BlockInput, Digest};
 use generic_array::typenum::{U32, U33};
 use generic_array::{ArrayLength, GenericArray};
 use num_bigint::{BigInt, Sign};
@@ -41,7 +41,10 @@ impl Group for ProjectivePoint {
 
     // Implements the `hash_to_curve()` function from
     // https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-3
-    fn hash_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, InternalError> {
+    fn hash_to_curve<H: BlockInput + Digest>(
+        msg: &[u8],
+        dst: &[u8],
+    ) -> Result<Self, InternalError> {
         // https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-8.2
         // `p: 2^256 - 2^224 + 2^192 + 2^96 - 1`
         const P: Lazy<BigInt> = Lazy::new(|| {
@@ -89,7 +92,10 @@ impl Group for ProjectivePoint {
 
     // Implements the `HashToScalar()` function from
     // https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-07.html#section-4.3
-    fn hash_to_scalar<H: Hash>(input: &[u8], dst: &[u8]) -> Result<Self::Scalar, InternalError> {
+    fn hash_to_scalar<H: BlockInput + Digest>(
+        input: &[u8],
+        dst: &[u8],
+    ) -> Result<Self::Scalar, InternalError> {
         // https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf#[{%22num%22:211,%22gen%22:0},{%22name%22:%22XYZ%22},70,700,0]
         // P-256 `n` is defined as `115792089210356248762697446949407573529996955224135760342 422259061068512044369`
         const N: Lazy<BigInt> = Lazy::new(|| {