Fixed memo

src/main/java/de/bitsharesmunich/graphenej/BrainKey.java

@@ -1,6 +1,7 @@
 package de.bitsharesmunich.graphenej;
 
 import de.bitsharesmunich.graphenej.crypto.AndroidRandomSource;
+import de.bitsharesmunich.graphenej.crypto.Random;
 import de.bitsharesmunich.graphenej.crypto.SecureRandomStrengthener;
 import org.bitcoinj.core.DumpedPrivateKey;
 import org.bitcoinj.core.ECKey;
@@ -43,9 +44,7 @@ public class BrainKey {
         String[] wordArray = words.split(",");
         ArrayList<String> suggestedBrainKey = new ArrayList<String>();
         assert (wordArray.length == DICT_WORD_COUNT);
-        SecureRandomStrengthener randomStrengthener = SecureRandomStrengthener.getInstance();
+        SecureRandom secureRandom = Random.getSecureRandom();
-        randomStrengthener.addEntropySource(new AndroidRandomSource());
-        SecureRandom secureRandom = randomStrengthener.generateAndSeedRandomNumberGenerator();
         int index;
         for (int i = 0; i < BRAINKEY_WORD_COUNT; i++) {
             index = secureRandom.nextInt(DICT_WORD_COUNT - 1);

src/main/java/de/bitsharesmunich/graphenej/Main.java

@@ -42,7 +42,7 @@ public class Main {
 //        test.testGetDynamicParams();
 //        test.testGetRequiredFeesSerialization();
 //        test.testRequiredFeesResponse();
-//        test.testTransactionBroadcastSequence();
+        test.testTransactionBroadcastSequence();
 //        test.testAccountLookupDeserialization();
 //        test.testPrivateKeyManipulations();
 //        test.testPublicKeyManipulations();
@@ -67,6 +67,7 @@ public class Main {
 //        test.testLookupAssetSymbols();
 //        test.testGetBlockHeader();
         //test.testGetLimitOrders();
-        test.testGetTradeHistory();
+//        test.testGetTradeHistory();
+//        test.testAssetSerialization();
     }
 }

src/main/java/de/bitsharesmunich/graphenej/Test.java

@@ -6,12 +6,10 @@ import com.google.common.primitives.UnsignedLong;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonArray;
-import com.google.gson.JsonElement;
 import com.google.gson.reflect.TypeToken;
 import de.bitsharesmunich.graphenej.errors.MalformedAddressException;
 import de.bitsharesmunich.graphenej.errors.MalformedTransactionException;
 import de.bitsharesmunich.graphenej.interfaces.WitnessResponseListener;
-import de.bitsharesmunich.graphenej.objects.MemoBuilder;
 import de.bitsharesmunich.graphenej.test.NaiveSSLContext;
 import com.neovisionaries.ws.client.*;
 import de.bitsharesmunich.graphenej.api.*;
@@ -300,15 +298,18 @@ public class Test {
         };
 
         try {
-            // Creating memo
             ECKey from = new BrainKey(Main.BILTHON_83_BRAIN_KEY, 0).getPrivateKey();
             PublicKey to = new PublicKey(ECKey.fromPublicOnly(new BrainKey(Main.BILTHON_5_BRAIN_KEY, 0).getPublicKey()));
-            Memo memo = new MemoBuilder().setFromKey(from).setToKey(to).setMessage("sample message").build();
+
+            // Creating memo
+            long nonce = 1;
+            byte[] encryptedMessage = Memo.encryptMessage(from, to, nonce, "another message");
+            Memo memo = new Memo(new Address(ECKey.fromPublicOnly(from.getPubKey())), new Address(to.getKey()), nonce, encryptedMessage);
 
             // Creating transaction
             Transaction transaction = new TransferTransactionBuilder()
-                    .setSource(new UserAccount("1.2.139270")) // bilthon-83
+                    .setSource(new UserAccount("1.2.138632")) // bilthon-83
-                    .setDestination(new UserAccount("1.2.142115")) // bilthon-5
+                    .setDestination(new UserAccount("1.2.139313")) // bilthon-5
                     .setAmount(new AssetAmount(UnsignedLong.valueOf(1), new Asset("1.3.0")))
                     .setFee(new AssetAmount(UnsignedLong.valueOf(264174), new Asset("1.3.0")))
                     .setPrivateKey(new BrainKey(Main.BILTHON_83_BRAIN_KEY, 0).getPrivateKey())
@@ -458,9 +459,9 @@ public class Test {
                 String suggestion = BrainKey.suggest(words);
                 brainKey = new BrainKey(suggestion, 0);
             } else {
-                System.out.println("Using brain key: " + Main.BILTHON_83_BRAIN_KEY);
+                System.out.println("Using brain key: " + Main.BILTHON_5_BRAIN_KEY);
-//                brainKey = new BrainKey(Main.BILTHON_83_BRAIN_KEY, 0);
+                brainKey = new BrainKey(Main.BILTHON_5_BRAIN_KEY, 0);
-                brainKey = new BrainKey("AMIDIC SKELIC CARLOAD CAPSULE FACY WONNED STICH BULBULE MESOLE SEMEED STRAVE PREBORN", 0);
+
             }
             ECKey key = brainKey.getPrivateKey();
             System.out.println("Private key..................: " + Util.bytesToHex(key.getSecretBytes()));
@@ -761,11 +762,11 @@ public class Test {
         ECKey from = new BrainKey(Main.BILTHON_83_BRAIN_KEY, 0).getPrivateKey();
         PublicKey to = new PublicKey(ECKey.fromPublicOnly(new BrainKey(Main.BILTHON_5_BRAIN_KEY, 0).getPublicKey()));
         
-        Memo sendMemo = new MemoBuilder().setFromKey(from).setToKey(to).setMessage("test message").build();
+//        Memo sendMemo = new MemoBuilder().setFromKey(from).setToKey(to).setMessage("test message").build();
         
-        JsonElement memoJson = sendMemo.toJsonObject();
+//        JsonElement memoJson = sendMemo.toJsonObject();
-        System.out.println("generated Json : " + memoJson.toString());
+//        System.out.println("generated Json : " + memoJson.toString());
-//        System.out.println("Decode Memo : " + Memo.decodeMessage(from, to, memoJson.getAsJsonObject().get("message").getAsString(), memoJson.getAsJsonObject().get("nonce").getAsString()));
+//        System.out.println("Decode Memo : " + Memo.decryptMessage(from, to, memoJson.getAsJsonObject().get("message").getAsString(), memoJson.getAsJsonObject().get("nonce").getAsString()));
     }
 
     public void testGetRelativeAccountHistory(){
@@ -974,4 +975,16 @@ public class Test {
             System.out.println("IOException. Msg: " + e.getMessage());
         }
     }
+
+    public void testAssetSerialization(){
+        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        DataOutput out = new DataOutputStream(byteArrayOutputStream);
+        try {
+            Varint.writeUnsignedVarLong(120, out);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        byte[] bytes = byteArrayOutputStream.toByteArray();
+        System.out.println("serialized: "+Util.bytesToHex(bytes));
+    }
 }

src/main/java/de/bitsharesmunich/graphenej/Util.java

@@ -33,6 +33,11 @@ public class Util {
     public static final int LZMA = 0;
     public static final int XZ = 1;
 
+    /**
+     * Converts an hexadecimal string to its corresponding byte[] value.
+     * @param s: String with hexadecimal numbers representing a byte array.
+     * @return: The actual byte array.
+     */
     public static byte[] hexToBytes(String s) {
         int len = s.length();
         byte[] data = new byte[len / 2];
@@ -43,6 +48,11 @@ public class Util {
         return data;
     }
 
+    /**
+     * Converts a byte array, into a user-friendly hexadecimal string.
+     * @param bytes: A byte array.
+     * @return: A string with the representation of the byte array.
+     */
     public static String bytesToHex(byte[] bytes) {
         char[] hexChars = new char[bytes.length * 2];
         for ( int j = 0; j < bytes.length; j++ ) {
@@ -53,6 +63,19 @@ public class Util {
         return new String(hexChars);
     }
 
+    /**
+     * Decodes an ascii string to a byte array.
+     * @param data: Arbitrary ascii-encoded string.
+     * @return: Array of bytes.
+     */
+    public static byte[] hexlify(String data){
+        ByteBuffer buffer = ByteBuffer.allocate(data.length());
+        for(char letter : data.toCharArray()){
+            buffer.put((byte) letter);
+        }
+        return buffer.array();
+    }
+
     /**
      * Utility function that compresses data using the LZMA algorithm.
      * @param inputBytes Input bytes of the data to be compressed.
@@ -168,6 +191,7 @@ public class Util {
             System.arraycopy(result, 32, ivBytes, 0, 16);
             byte[] sksBytes = new byte[32];
             System.arraycopy(result, 0, sksBytes, 0, 32);
+
             PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESFastEngine()));
             cipher.init(true, new ParametersWithIV(new KeyParameter(sksBytes), ivBytes));
             byte[] temp = new byte[input.length + (16 - (input.length % 16))];

src/main/java/de/bitsharesmunich/graphenej/crypto/Random.java

@@ -0,0 +1,15 @@
+package de.bitsharesmunich.graphenej.crypto;
+
+import java.security.SecureRandom;
+
+/**
+ * Created by nelson on 12/20/16.
+ */
+public class Random {
+
+    public static SecureRandom getSecureRandom(){
+        SecureRandomStrengthener randomStrengthener = SecureRandomStrengthener.getInstance();
+//        randomStrengthener.addEntropySource(new AndroidRandomSource());
+        return randomStrengthener.generateAndSeedRandomNumberGenerator();
+    }
+}

src/main/java/de/bitsharesmunich/graphenej/errors/ChecksumException.java

@@ -0,0 +1,10 @@
+package de.bitsharesmunich.graphenej.errors;
+
+/**
+ * Created by nelson on 12/20/16.
+ */
+public class ChecksumException extends Exception {
+    public ChecksumException(String message){
+        super(message);
+    }
+}

src/main/java/de/bitsharesmunich/graphenej/objects/Memo.java

@@ -3,17 +3,18 @@ package de.bitsharesmunich.graphenej.objects;
 import com.google.common.primitives.Bytes;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import de.bitsharesmunich.graphenej.Address;
 import de.bitsharesmunich.graphenej.PublicKey;
 import de.bitsharesmunich.graphenej.Util;
-import de.bitsharesmunich.graphenej.crypto.SecureRandomStrengthener;
+import de.bitsharesmunich.graphenej.errors.ChecksumException;
 import de.bitsharesmunich.graphenej.interfaces.ByteSerializable;
 import de.bitsharesmunich.graphenej.interfaces.JsonSerializable;
 import org.bitcoinj.core.ECKey;
+import org.spongycastle.math.ec.ECPoint;
 
-import java.math.BigInteger;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import java.security.SecureRandom;
+import java.util.Arrays;
 
 /**
  * Created by nelson on 11/9/16.
@@ -25,9 +26,9 @@ public class Memo implements ByteSerializable, JsonSerializable {
     public static final String KEY_NONCE = "nonce";
     public static final String KEY_MESSAGE = "message";
 
-    private ECKey from;
+    private Address from;
-    private PublicKey to;
+    private Address to;
-    private final byte[] nonce = new byte[8];
+    private long nonce;
     private byte[] message;
 
     /**
@@ -39,132 +40,175 @@ public class Memo implements ByteSerializable, JsonSerializable {
         this.message = null;
     }
 
+    /**
+     * Constructor used for private memos.
+     * @param from: Address of sender
+     * @param to: Address of recipient.
+     * @param nonce: Nonce used in the encryption.
+     * @param message: Message in ciphertext.
+     */
+    public Memo(Address from, Address to, long nonce, byte[] message){
+        this.from = from;
+        this.to = to;
+        this.nonce = nonce;
+        this.message = message;
+    }
+
+    /**
+     * Constructor intended to be used with public memos
+     * @param message: Message in plaintext.
+     */
+    public Memo(String message){
+        this.message = message.getBytes();
+    }
+
+    /**
+     * Method used to decrypt memo data.
+     * @param privateKey: Private key of the sender.
+     * @param publicKey: Public key of the recipient.
+     * @param nonce: The nonce.
+     * @param message: Plaintext message.
+     * @return: The encrypted version of the message.
+     */
+    public static byte[] encryptMessage(ECKey privateKey, PublicKey publicKey, long nonce, String message){
+        byte[] encrypted = null;
+        try {
+            MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
+            MessageDigest sha512 = MessageDigest.getInstance("SHA-512");
+
+            // Getting nonce bytes
+            String stringNonce = String.format("%d", nonce);
+            byte[] nonceBytes = Arrays.copyOfRange(Util.hexlify(stringNonce), 0, stringNonce.length());
+
+            // Getting shared secret
+            byte[] secret = publicKey.getKey().getPubKeyPoint().multiply(privateKey.getPrivKey()).normalize().getXCoord().getEncoded();
+
+            // SHA-512 of shared secret
+            byte[] ss = sha512.digest(secret);
+
+            byte[] seed = Bytes.concat(nonceBytes, Util.hexlify(Util.bytesToHex(ss)));
+
+            // Calculating checksum
+            byte[] sha256Msg = sha256.digest(message.getBytes());
+            byte[] checksum = Arrays.copyOfRange(sha256Msg, 0, 4);
+
+            // Concatenating checksum + message bytes
+            byte[] msgFinal = Bytes.concat(checksum, message.getBytes());
+
+            // Applying encryption
+            encrypted = Util.encryptAES(msgFinal, seed);
+        } catch (NoSuchAlgorithmException ex) {
+            System.out.println("NoSuchAlgotithmException. Msg:"+ ex.getMessage());
+        }
+        return encrypted;
+    }
+
+    /**
+     * Method used to encrypt memo data.
+     * @param privateKey: Private key of the sender.
+     * @param destinationAddress: Address of the recipient.
+     * @param nonce: The nonce.
+     * @param message: Plaintext message.
+     * @return: The encrypted version of the message.
+     */
+    public static byte[] encryptMessage(ECKey privateKey, Address destinationAddress, long nonce, String message){
+        return encryptMessage(privateKey, destinationAddress.getPublicKey(), nonce, message);
+    }
+
+
+    /**
+     * Method used to decrypt memo data.
+     * @param privateKey: The private key of the recipient.
+     * @param publicKey: The public key of the sender.
+     * @param nonce: The nonce.
+     * @param message: The encrypted message.
+     * @return: The plaintext version of the enrcrypted message.
+     * @throws ChecksumException
+     */
+    public static String decryptMessage(ECKey privateKey, PublicKey publicKey, long nonce, byte[] message) throws ChecksumException {
+        String plaintext = "";
+        try {
+            MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
+            MessageDigest sha512 = MessageDigest.getInstance("SHA-512");
+
+            // Getting nonce bytes
+            String stringNonce = String.format("%d", nonce);
+            byte[] nonceBytes = Arrays.copyOfRange(Util.hexlify(stringNonce), 0, stringNonce.length());
+
+            // Getting shared secret
+            byte[] secret = publicKey.getKey().getPubKeyPoint().multiply(privateKey.getPrivKey()).normalize().getXCoord().getEncoded();
+
+            // SHA-512 of shared secret
+            byte[] ss = sha512.digest(secret);
+
+            byte[] seed = Bytes.concat(nonceBytes, Util.hexlify(Util.bytesToHex(ss)));
+
+            // Calculating checksum
+            byte[] sha256Msg = sha256.digest(message);
+
+
+            // Applying decryption
+            byte[] temp = Util.decryptAES(message, seed);
+            byte[] checksum = Arrays.copyOfRange(temp, 0, 4);
+            byte[] decrypted = Arrays.copyOfRange(temp, 4, temp.length);
+            plaintext = new String(decrypted);
+            byte[] checksumConfirmation = Arrays.copyOfRange(sha256.digest(decrypted), 0, 4);
+            boolean checksumVerification = Arrays.equals(checksum, checksumConfirmation);
+            if(!checksumVerification){
+                throw new ChecksumException("Invalid checksum found while performing decryption");
+            }
+        } catch (NoSuchAlgorithmException e) {
+            System.out.println("NoSuchAlgotithmException. Msg:"+ e.getMessage());
+        }
+
+        return plaintext;
+    }
+
+    /**
+     * Method used to decrypt memo data.
+     * @param privateKey: The private key of the recipient.
+     * @param sourceAddress: The public address key of the sender.
+     * @param nonce: The nonce.
+     * @param message: The encrypted message.
+     * @return: The plaintext version of the enrcrypted message.
+     * @throws ChecksumException
+     */
+    public static String decryptMessage(ECKey privateKey, Address sourceAddress, long nonce, byte[] message) throws ChecksumException {
+        return decryptMessage(privateKey, sourceAddress.getPublicKey(), nonce, message);
+    }
+
+
     /**
      * Implement metod, serialized this Object
      * @return the byte array of this object serialized
      */
     @Override
     public byte[] toBytes() {
-        if ((this.from == null) || (this.to == null) || (this.message == null)) {
+        if ((this.from == null) && (this.to == null) && (this.message == null)) {
             return new byte[]{(byte) 0};
+        } else if(this.from == null && this.to == null & this.message != null){
+            return Bytes.concat(new byte[]{1},
+                    new byte[]{(byte)0},
+                    new byte[]{(byte)0},
+                    new byte[]{(byte)0},
+                    new byte[]{(byte) this.message.length},
+                    this.message);
         } else {
-            byte[] nonceformat = new byte[nonce.length];
+            byte[] nonceBytes = Util.revertLong(nonce);
-            for (int i = 0; i < nonceformat.length; i++) {
+
-                nonceformat[i] = nonce[nonce.length - i - 1];
+            ECPoint senderPoint = ECKey.compressPoint(from.getPublicKey().getKey().getPubKeyPoint());
+            PublicKey senderPublicKey = new PublicKey(ECKey.fromPublicOnly(senderPoint));
+
+            ECPoint recipientPoint = ECKey.compressPoint(to.getPublicKey().getKey().getPubKeyPoint());
+            PublicKey recipientPublicKey = new PublicKey(ECKey.fromPublicOnly(recipientPoint));
+
+            return Bytes.concat(new byte[]{1},
+                    senderPublicKey.toBytes(),
+                    recipientPublicKey.toBytes(),
+                    nonceBytes,
+                    new byte[]{(byte) this.message.length},
+                    this.message);
         }
-            org.spongycastle.math.ec.ECPoint point = ECKey.compressPoint(from.getPubKeyPoint());
-            PublicKey senderPublicKey = new PublicKey(ECKey.fromPublicOnly(point));
-
-            return Bytes.concat(new byte[]{1}, senderPublicKey.toBytes(), this.to.toBytes(), nonceformat, new byte[]{(byte) this.message.length}, this.message);
-        }
-    }
-
-    /**
-     * Encode a memo message using the input source key and destination key
-     * @param fromKey The source destination, need to have a private key accesss
-     * @param toKey The destination, needs only the public key access
-     * @param msg The message in bytes
-     * @return a Memo corresponding with the message encoding
-     */
-    public static Memo encodeMessage(ECKey fromKey, PublicKey toKey, byte[] msg) {
-        return encodeMessage(fromKey, toKey, msg, 0);
-    }
-
-    /**
-     * Encode a message a return a memo with that message encoded
-     *
-     * @param fromKey The source destination, need to have a private key accesss
-     * @param toKey The destination, needs only the public key access
-     * @param msg The message in bytes
-     * @param custom_nonce the custom nonce to be use or 0 to create a new one
-     * @return a Memo corresponding with the message encoding
-     */
-    public static Memo encodeMessage(ECKey fromKey, PublicKey toKey, byte[] msg, long custom_nonce) {
-        Memo memo = new Memo();
-        try {
-            MessageDigest md = MessageDigest.getInstance("SHA-256");
-
-            memo.from = fromKey;
-            memo.to = toKey;
-
-            if (custom_nonce == 0) {
-                SecureRandomStrengthener randomStrengthener = SecureRandomStrengthener.getInstance();
-//                randomStrengthener.addEntropySource(new AndroidRandomSource());
-                SecureRandom secureRandom = randomStrengthener.generateAndSeedRandomNumberGenerator();
-                secureRandom.nextBytes(memo.nonce);
-
-                long time = System.currentTimeMillis();
-
-                for (int i = 7; i >= 1; i--) {
-                    memo.nonce[i] = (byte) (time & 0xff);
-                    time = time / 0x100;
-                }
-            } else {
-                for (int i = 7; i >= 0; i--) {
-                    memo.nonce[i] = (byte) (custom_nonce & 0xff);
-                    custom_nonce = custom_nonce / 0x100;
-                }
-            }
-            byte[] secret = toKey.getKey().getPubKeyPoint().multiply(fromKey.getPrivKey()).normalize().getXCoord().getEncoded();
-            byte[] finalKey = new byte[secret.length + memo.nonce.length];
-            System.arraycopy(secret, 0, finalKey, 0, secret.length);
-            System.arraycopy(memo.nonce, 0, finalKey, secret.length, memo.nonce.length);
-
-            byte[] sha256Msg = md.digest(msg);
-            byte[] serialChecksum = new byte[4];
-            System.arraycopy(sha256Msg, 0, serialChecksum, 0, 4);
-            byte[] msgFinal = new byte[serialChecksum.length + msg.length];
-            System.arraycopy(serialChecksum, 0, msgFinal, 0, serialChecksum.length);
-            System.arraycopy(msg, 0, msgFinal, serialChecksum.length, msg.length);
-            memo.message = Util.encryptAES(msgFinal, finalKey);
-        } catch (NoSuchAlgorithmException ex) {
-        }
-        return memo;
-    }
-
-    /**
-     * returns the string coreesponding a encode memo
-     *
-     * @param fromKey The soruce key, need to have public key only
-     * @param toKey The destination key, need to have private key access
-     * @param msg The message to be decoded
-     * @param nonce The nonce used in the decoded message
-     * @return The message
-     */
-    public static String decodeMessage(PublicKey fromKey, ECKey toKey, byte[] msg, byte[] nonce) {
-
-        byte[] secret = fromKey.getKey().getPubKeyPoint().multiply(toKey.getPrivKey()).normalize().getXCoord().getEncoded();
-        byte[] finalKey = new byte[secret.length + nonce.length];
-        System.arraycopy(secret, 0, finalKey, 0, secret.length);
-        System.arraycopy(nonce, 0, finalKey, secret.length, nonce.length);
-
-        byte[] msgFinal = Util.decryptAES(msg, finalKey);
-        byte[] decodedMsg = new byte[msgFinal.length - 4];
-        //TODO verify checksum for integrity
-        System.arraycopy(msgFinal, 4, decodedMsg, 0, decodedMsg.length);
-        return new String(decodedMsg);
-    }
-
-    /**
-     * returns the string corresponding a encode memo
-     *
-     * @param fromKey The source key, need to have public key only
-     * @param toKey The destination key, need to have private key access
-     * @param message The message to be decoded
-     * @param nonce The nonce used in the decoded message
-     * @return The message
-     */
-    public static String decodeMessage(PublicKey fromKey, ECKey toKey, String message, String nonce) {
-        byte[] msg = new BigInteger(message, 16).toByteArray();
-        if (msg[0] == 0) {
-            byte[] temp = new byte[msg.length - 1];
-            System.arraycopy(msg, 1, temp, 0, temp.length);
-            msg = temp;
-        }
-        byte[] firstNonce = new BigInteger(nonce, 10).toByteArray();
-        byte[] nonceByte = new byte[8];
-        System.arraycopy(firstNonce, firstNonce.length - 8, nonceByte, 0, nonceByte.length);
-        return decodeMessage(fromKey, toKey, msg, nonceByte);
     }
 
     @Override
@@ -174,17 +218,19 @@ public class Memo implements ByteSerializable, JsonSerializable {
 
     @Override
     public JsonElement toJsonObject() {
-        if ((this.from == null) || (this.to == null) || (this.nonce == null) || (this.message == null)) {
-            return null;
-        }
-        org.spongycastle.math.ec.ECPoint point = ECKey.compressPoint(from.getPubKeyPoint());
-        PublicKey publicKey = new PublicKey(ECKey.fromPublicOnly(point));
-
         JsonObject memoObject = new JsonObject();
-        memoObject.addProperty(KEY_FROM, publicKey.getAddress());
+        if ((this.from == null) && (this.to == null)) {
-        memoObject.addProperty(KEY_TO, this.to.getAddress());
+            // Public memo
-        memoObject.addProperty(KEY_NONCE, new BigInteger(1, this.nonce).toString(10));
+            memoObject.addProperty(KEY_FROM, "");
-        memoObject.addProperty(KEY_MESSAGE, new BigInteger(1, this.message).toString(16));
+            memoObject.addProperty(KEY_TO, "");
+            memoObject.addProperty(KEY_NONCE, "");
+            memoObject.addProperty(KEY_MESSAGE, Util.bytesToHex(this.message));
+        }else{
+            memoObject.addProperty(KEY_FROM, this.from.toString());
+            memoObject.addProperty(KEY_TO, this.to.toString());
+            memoObject.addProperty(KEY_NONCE, String.format("%d", this.nonce));
+            memoObject.addProperty(KEY_MESSAGE, Util.bytesToHex(this.message));
+        }
         return memoObject;
     }
 }

src/main/java/de/bitsharesmunich/graphenej/objects/MemoBuilder.java

@@ -1,74 +0,0 @@
-package de.bitsharesmunich.graphenej.objects;
-
-import de.bitsharesmunich.graphenej.PublicKey;
-import org.bitcoinj.core.ECKey;
-
-/**
- * Class to build a Memo Object
- * @author henry 10/12/2016
- */
-public class MemoBuilder {
-
-    private ECKey fromKey;
-    private PublicKey toKey;
-    private String message;
-    private long nonce = 0;
-
-    /**
-     * Empty Constructor
-     */
-    public MemoBuilder() {
-    }
-
-    /**
-     * Set the key of the Source, needs to have a private Key access
-     * @param fromKey The Public Key of the sender
-     * @return The MemoBuilder
-     */
-    public MemoBuilder setFromKey(ECKey fromKey) {
-        this.fromKey = fromKey;
-        return this;
-    }
-
-    /**
-     * Set the key of the destination, only need the public key.
-     * @param toKey The Public Key of the receiver
-     * @return  The MemoBuilder
-     */
-    public MemoBuilder setToKey(PublicKey toKey) {
-        this.toKey = toKey;
-        return this;
-    }
-
-    /**
-     * Set the message to be send
-     * @param message The message as a String
-     * @return  The MemoBuilder
-     */
-    public MemoBuilder setMessage(String message) {
-        this.message = message;
-        return this;
-    }
-
-    /**
-     * (Optional) Sets a custom nonce
-     * @param nonce The custom nonce
-     * @return The MemoBuilder
-     */
-    public MemoBuilder setNone(Long nonce) {
-        this.nonce = nonce;
-        return this;
-    }
-
-    /**
-     * Biulds the memo object
-     * @return The Memo object
-     */
-    public Memo build() {
-        //Todo unencode key
-        if (nonce == 0) {
-            return Memo.encodeMessage(fromKey, toKey, message.getBytes());
-        }
-        return Memo.encodeMessage(fromKey, toKey, message.getBytes(), nonce);
-    }
-}

src/test/java/de/bitsharesmunich/graphenej/objects/MemoTest.java

@@ -0,0 +1,105 @@
+package de.bitsharesmunich.graphenej.objects;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import de.bitsharesmunich.graphenej.Address;
+import de.bitsharesmunich.graphenej.Util;
+import de.bitsharesmunich.graphenej.errors.ChecksumException;
+import org.bitcoinj.core.DumpedPrivateKey;
+import org.bitcoinj.core.ECKey;
+import org.junit.*;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Created by nelson on 12/19/16.
+ */
+public class MemoTest {
+
+    private ECKey sourcePrivate;
+    private Address sourceAddress;
+
+    private ECKey destinationPrivate;
+    private Address destinationAddress;
+
+    private long nonce;
+    private String shortMessage = "test";
+    private String longerMessage = "testing now longer string!!";
+
+    private byte[] shortEncryptedMessage = Util.hexToBytes("4c81c2db6ebc61e3f9e0ead65c0559dd");
+    private byte[] longerEncryptedMessage = Util.hexToBytes("1f8a08f1ff53dcefd48eeb052d26fba425f2a917f508ce61fc3d5696b10efa17");
+
+    private String decodedMessage;
+
+    @Before
+    public void setUp() throws Exception {
+        sourcePrivate = DumpedPrivateKey.fromBase58(null, "5J96pne45qWM1WpektoeazN6k9Mt93jQ7LyueRxFfEMTiy6yxjM").getKey();
+        destinationPrivate = DumpedPrivateKey.fromBase58(null, "5HuGQT8qwHScBgD4XsGbQUmXQF18MrbzxaQDiGGXFNRrCtqgT5Q").getKey();
+
+        sourceAddress = new Address("BTS8RiFgs8HkcVPVobHLKEv6yL3iXcC9SWjbPVS15dDAXLG9GYhnY");
+        destinationAddress = new Address("BTS8ADjGaswhfFoxMGxqCdBtzhTBJsrGadCLoc9Ey5AGc8eoVZ5bV");
+
+        nonce = 5;
+    }
+
+    @Test
+    public void shouldMatchPredefinedChiphertext(){
+        byte[] encrypted = Memo.encryptMessage(sourcePrivate, destinationAddress, 1, shortMessage);
+        assertArrayEquals("Testing with short message and nonce 1", encrypted, shortEncryptedMessage);
+
+        byte[] encryptedLong = Memo.encryptMessage(sourcePrivate, destinationAddress, 1, longerMessage);
+        assertArrayEquals("Testing with longer message and nonce 1", encryptedLong, longerEncryptedMessage);
+    }
+
+    @Test
+    public void shouldEncryptAndDecryptShortMessage(){
+        try {
+            byte[] encrypted = Memo.encryptMessage(sourcePrivate, destinationAddress, nonce, shortMessage);
+            String decrypted = decrypted = Memo.decryptMessage(destinationPrivate, sourceAddress, nonce, encrypted);
+            assertEquals("Decrypted message must be equal to original", decrypted, shortMessage);
+        } catch (ChecksumException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Test
+    public void shouldEncryptAndDecryptLongerMessage(){
+        try{
+            byte[] longEncrypted = Memo.encryptMessage(sourcePrivate, destinationAddress, nonce, longerMessage);
+            String longDecrypted = Memo.decryptMessage(destinationPrivate, sourceAddress, nonce, longEncrypted);
+            assertEquals("The longer message must be equal to the original", longerMessage, longDecrypted);
+        } catch (ChecksumException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Test(expected = ChecksumException.class)
+    public void shouldThrowException() throws ChecksumException {
+        byte[] corrupted = Memo.encryptMessage(sourcePrivate, destinationAddress, nonce, longerMessage);
+        corrupted[0] = 0;
+        String longDecrypted = Memo.decryptMessage(destinationPrivate, sourceAddress, nonce, corrupted);
+    }
+
+    @Test
+    public void shouldBeJsonObjectSerializable(){
+        byte[] encrypted = Memo.encryptMessage(sourcePrivate, destinationAddress, 1, shortMessage);
+        Memo memo = new Memo(sourceAddress, destinationAddress, 1, encrypted);
+        JsonElement jsonObject = memo.toJsonObject();
+        JsonObject reference = new JsonObject();
+        reference.addProperty("from", "BTS8RiFgs8HkcVPVobHLKEv6yL3iXcC9SWjbPVS15dDAXLG9GYhnY");
+        reference.addProperty("to", "BTS8ADjGaswhfFoxMGxqCdBtzhTBJsrGadCLoc9Ey5AGc8eoVZ5bV");
+        reference.addProperty("nonce", "1");
+        reference.addProperty("message", "4c81c2db6ebc61e3f9e0ead65c0559dd");
+        assertEquals("Memo instance should generate a valid JsonObject",jsonObject, reference);
+    }
+
+    @Test
+    public void shouldBeByteSerializable(){
+        String byteReference = "0103d1fb8c7421db64d46fba7e36f428854ca06eff65698b293f37c7ffaa54e2c2b203aece7c31616c02fcc96b50d3397c0e8d33d6384655d477c300d9196c728a5ee20100000000000000104c81c2db6ebc61e3f9e0ead65c0559dd";
+        byte[] encrypted = Memo.encryptMessage(sourcePrivate, destinationAddress, 1, shortMessage);
+        Memo memo = new Memo(sourceAddress, destinationAddress, 1, encrypted);
+        byte[] memoBytes = memo.toBytes();
+        assertEquals("Memo instance should generate a valid byte array", byteReference, Util.bytesToHex(memoBytes));
+    }
+}