diff --git a/src/miner.cpp b/src/miner.cpp
index 3b0335a2b..8b5941dd9 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -1134,36 +1134,45 @@ void static RandomXMiner()
                 hashTarget = HASHTarget;
 
                 char randomxHash[RANDOMX_HASH_SIZE];
-                // Initial randomx key is chain magic + first letter of chain name which is 2^40 bits of entropy
-                char randomxKey[5];
+                // Initial randomx key is chain magic || ac_name which is >= 2^40 bits of entropy assuming strlen(ac_name) >= 1
+                // For ac_name=DRAGONX we have 4 + 7 = 11 bytes or 2^88 bits of entropy
+                char randomxKey[4 + strlen(SMART_CHAIN_SYMBOL)];
                 randomxKey[0] = ASSETCHAINS_MAGIC & 0xff;
                 randomxKey[1] = (ASSETCHAINS_MAGIC >> 8) & 0xff;
                 randomxKey[2] = (ASSETCHAINS_MAGIC >> 16) & 0xff;
                 randomxKey[3] = (ASSETCHAINS_MAGIC >> 24) & 0xff;
-                randomxKey[4] = SMART_CHAIN_SYMBOL[0];
+
+                for(int i=0; i++; i<strlen(SMART_CHAIN_SYMBOL) ) {
+                    randomxKey[4+i] = SMART_CHAIN_SYMBOL[i];
+                }
 
                 crypto_generichash_blake2b_state state;
                 // Hash = blake2b( key || ac_name)
-                crypto_generichash_blake2b_update(&state, (unsigned char*)&randomxKey[0], 5);
+                crypto_generichash_blake2b_update(&state, (unsigned char*)&randomxKey[0], 4 + strlen(SMART_CHAIN_SYMBOL));
                 crypto_generichash_blake2b_update(&state, (unsigned char*)&SMART_CHAIN_SYMBOL[0], strlen(SMART_CHAIN_SYMBOL));
                 uchar randomxInput[32];
                 crypto_generichash_blake2b_final(&state, randomxInput, 32);
 
                 randomx_flags flags         = randomx_get_flags();
                 randomx_cache *randomxCache = randomx_alloc_cache(flags);
-
-                if(Mining_height > 1024 && (Mining_height % 1024 == 64)) {
-                    // At block height 1024*N+64 we should use the blockhash of block 1024*N as key
-                    // use blockchain data to set a new key+input for a group of blocks
-                    // randomxKey = ...
-                    // randomxInput = ...
-                }
-
                 if (randomxCache == NULL) {
                     LogPrintf("RandomX cache is null, something is wrong, cannot mine!\n");
                     return;
                 }
 
+
+                // TODO: use same block key for groups of blocks
+                if(Mining_height > 1024 && (Mining_height % 1024 == 64)) {
+                    // At block height 1024*N+64 we should use the blockhash of block 1024*N as randomx key
+                    // use blockchain data to set a new key+input for a group of blocks
+                    uint256 randomxBlockKey;
+                    randomxBlockKey = chainActive[Mining_height - 64]->GetBlockHash();
+                    crypto_generichash_blake2b_state new_state;
+                    crypto_generichash_blake2b_update(&state, (unsigned char*)&randomxBlockKey, 32);
+                    crypto_generichash_blake2b_final(&state, randomxInput, 32);
+                }
+
+                // TODO: use correct variables
                 randomx_init_cache(randomxCache, &randomxKey, sizeof randomxKey);
                 randomx_vm *myVM = randomx_create_vm(flags, randomxCache, NULL);