- hkdf_extract(sha, &bidirectional_state.ck, &[0; 0], &mut prk);
- hkdf_expand(sha, &prk, &[0;0], &mut final_hkdf);
+ hkdf_extract(Sha256::new(), &bidirectional_state.ck, &[0; 0], &mut prk);
+ hkdf_expand(Sha256::new(), &prk, &[0;0], &mut final_hkdf);