Ozan/persistent merkle tree

src/main/java/model/Entity.java

@@ -1,5 +1,7 @@
 package model;
 
+import java.io.Serializable;
+
 import crypto.Sha3256Hasher;
 import model.codec.EncodedEntity;
 import model.crypto.Hash;
@@ -10,7 +12,7 @@
  * Entity represents the unit of data model in LightChain. Everything meant to be sent over the network, stored
  * in memory, or a database must extend the Entity class.
  */
-public abstract class Entity {
+public abstract class Entity implements Serializable {
   /**
    * Computes the collision resistant hash value of entity.
    *

src/main/java/model/codec/EntityType.java

@@ -9,4 +9,5 @@ public class EntityType {
   public static final String TYPE_VALIDATED_TRANSACTION = "type-lightchain-validated-transaction";
   public static final String TYPE_VALIDATED_BLOCK = "type-lightchain-validated-block";
   public static final String TYPE_ECDSA_SIGNATURE = "type-lightchain-ecdsa-signature";
+  public static final String TYPE_ACCOUNT = "type-lightchain-account";
 }

src/main/java/model/crypto/Hash.java

@@ -1,11 +1,13 @@
 package model.crypto;
 
+import java.io.Serializable;
+
 import model.lightchain.Identifier;
 
 /**
  * Represents abstract data type for the cryptographic hash function used in LightChain.
  */
-public abstract class Hash {
+public abstract class Hash implements Serializable {
   /**
    * Actual value of hash in bytes.
    */

src/main/java/model/crypto/Sha3256Hash.java

@@ -1,5 +1,6 @@
 package model.crypto;
 
+import java.io.Serializable;
 import java.util.Arrays;
 
 import model.lightchain.Identifier;
@@ -8,7 +9,7 @@
  * Represents SHA3-256 data type which extends abstract Hash data type for
  * the cryptographic hash function used in LightChain.
  */
-public class Sha3256Hash extends Hash {
+public class Sha3256Hash extends Hash implements Serializable {
   public static final int Size = 32;
   private final byte[] hashBytes;
 

src/main/java/model/lightchain/Account.java

@@ -1,11 +1,13 @@
 package model.lightchain;
 
+import model.Entity;
+import model.codec.EntityType;
 import model.crypto.PublicKey;
 
 /**
  * Represents a LightChain account which is the constituent of the SnapShot.
  */
-public class Account {
+public class Account extends Entity {
   /**
    * Unique identifier of the account.
    */
@@ -72,4 +74,24 @@ public Identifier getLastBlockId() {
   public int getStake() {
     return this.stake;
   }
-}
+
+  /**
+   * Type of this entity.
+   *
+   * @return type of this entity.
+   */
+  @Override
+  public String type() {
+    return EntityType.TYPE_ACCOUNT;
+  }
+
+  /**
+   * Identifier of this account.
+   *
+   * @return identifier of this Account
+   */
+  @Override
+  public Identifier id() {
+    return this.identifier;
+  }
+}

src/main/java/model/lightchain/Identifier.java

@@ -1,13 +1,14 @@
 package model.lightchain;
 
+import java.io.Serializable;
 import java.util.Arrays;
 
 import io.ipfs.multibase.Multibase;
 
 /**
  * Represents a 32-byte unique identifier for an entity. Normally is computed as the hash value of the entity.
  */
-public class Identifier {
+public class Identifier implements Serializable {
   public static final int Size = 32;
   private final byte[] value;
 

src/main/java/modules/ads/AuthenticatedDataStructure.java

@@ -7,9 +7,23 @@
  * Models AuthenticatedDataStructure (ADS) and a key-value store of entities supported with membership proofs.
  */
 public interface AuthenticatedDataStructure {
+
+  /**
+   * Puts the given entity into the merkle tree and return AuthenticationEntity.
+   *
+   * @param e the entity to be put into the merkle tree
+   *
+   * @return AuthenticationEntity of the given entity
+   */
   AuthenticatedEntity put(Entity e);
 
+  /**
+   * Return the AuthenticationEntity of the given identifier.
+   *
+   * @param id the identifier whose AuthenticationEntity is to be returned
+   *
+   * @return the AuthenticationEntity of the given identifier
+   */
   AuthenticatedEntity get(Identifier id);
 
-  int size();
 }

src/main/java/modules/ads/AuthenticatedEntity.java

@@ -1,12 +1,14 @@
 package modules.ads;
 
+import java.io.Serializable;
+
 import model.Entity;
 
 /**
  * AuthenticatedEntity is a wrapper model around the Entity type that also contains a membership Merkle Proof for
  * that entity against a root identifier.
  */
-public abstract class AuthenticatedEntity extends Entity {
+public abstract class AuthenticatedEntity extends Entity implements Serializable {
   public abstract Entity getEntity();
 
   public abstract MembershipProof getMembershipProof();

src/main/java/modules/ads/MembershipProof.java

@@ -1,13 +1,14 @@
 package modules.ads;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 
 import model.crypto.Sha3256Hash;
 
 /**
  * Represents a Merkle Proof of membership against a certain root identifier.
  */
-public interface MembershipProof {
+public interface MembershipProof extends Serializable {
   /**
    * Root of the authenticated data structure that this proof belongs to.
    *

src/main/java/modules/ads/merkletree/MerkleNode.java

@@ -1,5 +1,10 @@
 package modules.ads.merkletree;
 
+import java.io.Serializable;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+
+import com.google.gson.Gson;
 import crypto.Sha3256Hasher;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import model.Entity;
@@ -8,7 +13,7 @@
 /**
  * A node in the Merkle tree.
  */
-public class MerkleNode {
+public class MerkleNode implements Serializable {
   private static final Sha3256Hasher hasher = new Sha3256Hasher();
   private MerkleNode left;
   private MerkleNode right;
@@ -70,34 +75,67 @@ public MerkleNode(Sha3256Hash hash, MerkleNode left, MerkleNode right) {
     this.hash = hash;
   }
 
+  /**
+   * Returns the left child of the node.
+   *
+   * @return the left child of the node
+   */
   @SuppressFBWarnings(value = "EI_EXPOSE_REP", justification = "internal representation is intentionally returned")
   public MerkleNode getLeft() {
     return left;
   }
 
+  /**
+   * Returns the right child of the node.
+   *
+   * @return the right child of the node
+   */
   @SuppressFBWarnings(value = "EI_EXPOSE_REP", justification = "internal representation is intentionally returned")
   public MerkleNode getRight() {
     return right;
   }
 
+  /**
+   * Returns the parent node of the node.
+   *
+   * @return the parent node of the node
+   */
   @SuppressFBWarnings(value = "EI_EXPOSE_REP", justification = "internal representation is intentionally returned")
   public MerkleNode getParent() {
     return parent;
   }
 
+  /**
+   * Sets the parent node of the node.
+   */
   @SuppressFBWarnings(value = "EI_EXPOSE_REP2", justification = "parent is intentionally mutable externally")
   public void setParent(MerkleNode parent) {
     this.parent = parent;
   }
 
+  /**
+   * Returns the hash of the node.
+   *
+   * @return the hash of the node
+   */
   public Sha3256Hash getHash() {
     return hash;
   }
 
+  /**
+   * Returns the isLeft boolean of the node.
+   *
+   * @return the isLeft boolean of the node
+   */
   public boolean isLeft() {
     return isLeft;
   }
 
+  /**
+   * Sets the isLeft of the node.
+   *
+   * @param isLeft isLeft boolean of the node
+   */
   public void setLeft(boolean isLeft) {
     this.isLeft = isLeft;
   }
@@ -114,4 +152,44 @@ public MerkleNode getSibling() {
       return parent.getLeft();
     }
   }
+
+  /**
+   * Returns if o is equal to this node.
+   *
+   * @param o object to compare
+   *
+   * @return true if o is equal to this node
+   */
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    MerkleNode that = (MerkleNode) o;
+    return hash.equals(that.hash);
+  }
+
+  /**
+   * Returns the hash code of the node.
+   *
+   * @return the hash code of the node
+   */
+  @Override
+  public int hashCode() {
+    return Objects.hash(left, right, parent, isLeft, hash);
+  }
+
+  /**
+   * Returns the byte array representation of the node.
+   *
+   * @return the byte array representation of the node
+   */
+  public byte[] getBytes() {
+    Gson gson = new Gson();
+    byte[] bytes = gson.toJson(this).getBytes(StandardCharsets.UTF_8);
+    return bytes;
+  }
 }

src/main/java/modules/ads/merkletree/MerkleProof.java

@@ -1,5 +1,6 @@
 package modules.ads.merkletree;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Objects;
@@ -11,7 +12,7 @@
 /**
  * A proof of membership in a Merkle tree.
  */
-public class MerkleProof implements MembershipProof {
+public class MerkleProof implements MembershipProof, Serializable {
   private ArrayList<Sha3256Hash> path;
   private final ArrayList<Boolean> isLeftNode;
   private final Sha3256Hash root;