+void sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
+ const u8 *data, size_t data_len, u8 *buf,
+ size_t buf_len_bits);
+void tls_prf_sha256(const u8 *secret, size_t secret_len,
+ const char *label, const u8 *seed, size_t seed_len,
+ u8 *out, size_t outlen);
+int hmac_sha256_kdf(const u8 *secret, size_t secret_len,
+ const char *label, const u8 *seed, size_t seed_len,
+ u8 *out, size_t outlen);