-void sha256_prf(const u8 *key, size_t key_len, const char *label,
- const u8 *data, size_t data_len, u8 *buf, size_t buf_len);
-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);
+int sha256_prf(const u8 *key, size_t key_len, const char *label,
+ const u8 *data, size_t data_len, u8 *buf, size_t buf_len);
+int 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);