Added utils to help make extraData strings (#87)

consensus/clique/src/main/java/tech/pegasys/pantheon/consensus/clique/CliqueExtraData.java

@@ -15,8 +15,11 @@ package tech.pegasys.pantheon.consensus.clique;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import tech.pegasys.pantheon.crypto.SECP256K1.PrivateKey;
+import tech.pegasys.pantheon.crypto.SECP256K1.PublicKey;
 import tech.pegasys.pantheon.crypto.SECP256K1.Signature;
 import tech.pegasys.pantheon.ethereum.core.Address;
+import tech.pegasys.pantheon.ethereum.core.Util;
 import tech.pegasys.pantheon.util.bytes.BytesValue;
 import tech.pegasys.pantheon.util.bytes.BytesValues;
 
@@ -106,4 +109,21 @@ public class CliqueExtraData {
   public List<Address> getValidators() {
     return validators;
   }
+
+  public static String createGenesisExtraDataString(final List<PrivateKey> privKeys) {
+    final List<Address> validators = convertPrivKeysToAddresses(privKeys);
+    final CliqueExtraData cliqueExtraData =
+        new CliqueExtraData(BytesValue.wrap(new byte[32]), null, validators);
+    final BytesValue output = cliqueExtraData.encode();
+    return output.toString();
+  }
+
+  private static List<Address> convertPrivKeysToAddresses(final List<PrivateKey> privKeys) {
+    final List<Address> validators = Lists.newArrayList();
+    for (PrivateKey privKey : privKeys) {
+      final PublicKey pubKey = PublicKey.create(privKey);
+      validators.add(Util.publicKeyToAddress(pubKey));
+    }
+    return validators;
+  }
 }

consensus/clique/src/test/java/tech/pegasys/pantheon/consensus/clique/CliqueExtraDataTest.java

@@ -15,15 +15,20 @@ package tech.pegasys.pantheon.consensus.clique;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
+import tech.pegasys.pantheon.crypto.SECP256K1.KeyPair;
+import tech.pegasys.pantheon.crypto.SECP256K1.PrivateKey;
 import tech.pegasys.pantheon.crypto.SECP256K1.Signature;
 import tech.pegasys.pantheon.ethereum.core.Address;
 import tech.pegasys.pantheon.ethereum.core.AddressHelpers;
+import tech.pegasys.pantheon.ethereum.core.Util;
 import tech.pegasys.pantheon.util.bytes.BytesValue;
 
 import java.math.BigInteger;
 import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Collectors;
 
+import com.google.common.collect.Lists;
 import org.bouncycastle.util.encoders.Hex;
 import org.junit.Test;
 
@@ -88,4 +93,28 @@ public class CliqueExtraDataTest {
         .isInstanceOf(IllegalArgumentException.class)
         .hasMessage("BytesValue is of invalid size - i.e. contains unused bytes.");
   }
+
+  @Test
+  public void privKeysToExtraDataString() {
+    List<KeyPair> nodeKeys = Lists.newArrayList();
+    for (int i = 0; i < 4; i++) {
+      nodeKeys.add(KeyPair.generate());
+    }
+
+    final List<PrivateKey> privKeys =
+        nodeKeys.stream().map(k -> k.getPrivateKey()).collect(Collectors.toList());
+
+    final String hexOutput = CliqueExtraData.createGenesisExtraDataString(privKeys);
+
+    final CliqueExtraData extraData = CliqueExtraData.decode(BytesValue.fromHexString(hexOutput));
+
+    final List<Address> expectedAddresses =
+        nodeKeys
+            .stream()
+            .map(k -> Util.publicKeyToAddress(k.getPublicKey()))
+            .collect(Collectors.toList());
+
+    assertThat(extraData.getValidators())
+        .containsExactly(expectedAddresses.toArray(new Address[expectedAddresses.size()]));
+  }
 }