-void twister256_nextBlock(twister256_ctx_t* ctx, void* msg);
-void twister256_lastBlock(twister256_ctx_t* ctx, void* msg, uint16_t length_b);
+void twister256_nextBlock(twister256_ctx_t* ctx, const void* msg);
+void twister256_lastBlock(twister256_ctx_t* ctx, const void* msg, uint16_t length_b);