An implementation of [serde::Serializer] serializing directly into a hash digest (anything implementing [digest::Update]).
use digest::Digest;
use k256::ecdsa::SigningKey;
use rand_core::OsRng;
use serde::Serialize;
use sha2::Sha256;
use hashing_serializer::HashSerializer;
let sk = SigningKey::random(&mut OsRng);
let vk = sk.verifying_key();
let mut digest = Sha256::new();
let serializer = HashingSerializer { digest: &mut digest };
vk.serialize(serializer).unwrap();