-void twister384_nextBlock(twister384_ctx_t* ctx, void* msg);
-void twister384_lastBlock(twister384_ctx_t* ctx, void* msg, uint16_t length_b);
+void twister384_nextBlock(twister384_ctx_t* ctx, const void* msg);
+void twister384_lastBlock(twister384_ctx_t* ctx, const void* msg, uint16_t length_b);