Add support for "only one registered name per account" + de-static brokenMD160 blockchain flag

src/main/java/org/qora/block/BlockChain.java

@@ -84,8 +84,11 @@ public class BlockChain {
 	@XmlJavaTypeAdapter(StringLongMapXmlAdapter.class)
 	private Map<String, Long> featureTriggers;
 
-	// This property is slightly different as we need it early and we want to avoid getInstance() loop
-	private static boolean useBrokenMD160ForAddresses = false;
+	/** Whether to use legacy, broken RIPEMD160 implementation when converting public keys to addresses. */
+	private boolean useBrokenMD160ForAddresses = false;
+
+	/** Whether only one registered name is allowed per account. */
+	private boolean oneNamePerAccount = false;
 
 	// Constructors, etc.
 
@@ -217,8 +220,12 @@ public class BlockChain {
 		return this.defaultGroupId;
 	}
 
-	public static boolean getUseBrokenMD160ForAddresses() {
-		return useBrokenMD160ForAddresses;
+	public boolean getUseBrokenMD160ForAddresses() {
+		return this.useBrokenMD160ForAddresses;
+	}
+
+	public boolean oneNamePerAccount() {
+		return this.oneNamePerAccount;
 	}
 
 	// Convenience methods for specific blockchain feature triggers

src/main/java/org/qora/crypto/Crypto.java

@@ -50,7 +50,7 @@ public class Crypto {
 		byte[] inputHash = digest(input);
 
 		// Use RIPEMD160 to create shorter address
-		if (BlockChain.getUseBrokenMD160ForAddresses()) {
+		if (BlockChain.getInstance().getUseBrokenMD160ForAddresses()) {
 			// Legacy BROKEN MD160
 			BrokenMD160 brokenMD160 = new BrokenMD160();
 			inputHash = brokenMD160.digest(inputHash);

src/main/java/org/qora/transaction/RegisterNameTransaction.java

@@ -8,6 +8,7 @@ import java.util.List;
 import org.qora.account.Account;
 import org.qora.account.PublicKeyAccount;
 import org.qora.asset.Asset;
+import org.qora.block.BlockChain;
 import org.qora.crypto.Crypto;
 import org.qora.data.transaction.RegisterNameTransactionData;
 import org.qora.data.transaction.TransactionData;
@@ -75,6 +76,12 @@ public class RegisterNameTransaction extends Transaction {
 
 	@Override
 	public ValidationResult isValid() throws DataException {
+		Account registrant = getRegistrant();
+
+		// If accounts are only allowed one registered name then check for this
+		if (BlockChain.getInstance().oneNamePerAccount() && !this.repository.getNameRepository().getNamesByOwner(registrant.getAddress()).isEmpty())
+			return ValidationResult.MULTIPLE_NAMES_FORBIDDEN;
+
 		// Check owner address is valid
 		if (!Crypto.isValidAddress(registerNameTransactionData.getOwner()))
 			return ValidationResult.INVALID_ADDRESS;
@@ -102,8 +109,6 @@ public class RegisterNameTransaction extends Transaction {
 			return ValidationResult.NEGATIVE_FEE;
 
 		// Check reference is correct
-		Account registrant = getRegistrant();
-
 		if (!Arrays.equals(registrant.getLastReference(), registerNameTransactionData.getReference()))
 			return ValidationResult.INVALID_REFERENCE;
 

src/main/java/org/qora/transaction/Transaction.java

@@ -186,6 +186,7 @@ public abstract class Transaction {
 		TRANSACTION_ALREADY_CONFIRMED(66),
 		INVALID_TX_GROUP_ID(67),
 		TX_GROUP_ID_MISMATCH(68),
+		MULTIPLE_NAMES_FORBIDDEN(69),
 		NOT_YET_RELEASED(1000);
 
 		public final int value;

src/test/java/org/qora/test/CryptoTests.java

@@ -31,7 +31,7 @@ public class CryptoTests extends Common {
 	@Test
 	public void testPublicKeyToAddress() {
 		byte[] publicKey = HashCode.fromString("775ada64a48a30b3bfc4f1db16bca512d4088704975a62bde78781ce0cba90d6").asBytes();
-		String expected = BlockChain.getUseBrokenMD160ForAddresses() ? "QUD9y7NZqTtNwvSAUfewd7zKUGoVivVnTW" : "QPc6TvGJ5RjW6LpwUtafx7XRCdRvyN6rsA";
+		String expected = BlockChain.getInstance().getUseBrokenMD160ForAddresses() ? "QUD9y7NZqTtNwvSAUfewd7zKUGoVivVnTW" : "QPc6TvGJ5RjW6LpwUtafx7XRCdRvyN6rsA";
 
 		assertEquals(expected, Crypto.toAddress(publicKey));
 	}