-void hmac_sha256_init(hmac_sha256_ctx_t *s, void* key, uint16_t keylength_b);
-void hmac_sha256_final(hmac_sha256_ctx_t *s, void* key, uint16_t keylength_b);
-void hmac_sha256(void* dest, void* key, uint16_t keylength_b, void* msg, uint64_t msglength_b);
+
+void hmac_sha256_init(hmac_sha256_ctx_t *s, const void* key, uint16_t keylength_b);
+void hmac_sha256_nextBlock(hmac_sha256_ctx_t *s, const void* block);
+void hmac_sha256_lastBlock(hmac_sha256_ctx_t *s, const void* block, uint16_t length_b);
+void hmac_sha256_final(void* dest, hmac_sha256_ctx_t *s);
+
+void hmac_sha256(void* dest, const void* key, uint16_t keylength_b, const void* msg, uint32_t msglength_b);