Add serialization for inbound group session

- remove compiler warnings when logs are not enabled
- new getInstanceId() function to refactor code

16 files changed, 490 insertions, 292 deletions

diff --git a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmGroupSessionTest.java b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmGroupSessionTest.java
index d49ebd4..c2a266b 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmGroupSessionTest.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmGroupSessionTest.java
@@ -28,7 +28,8 @@ import static org.junit.Assert.assertTrue;
 @FixMethodOrder(MethodSorters.NAME_ASCENDING)
 public class OlmGroupSessionTest {
     private static final String LOG_TAG = "OlmSessionTest";
-    private final String FILE_NAME_SERIAL_SESSION = "SerialGroupSession";
+    private final String FILE_NAME_SERIAL_OUT_SESSION = "SerialOutGroupSession";
+    private final String FILE_NAME_SERIAL_IN_SESSION = "SerialInGroupSession";
 
     private static OlmManager mOlmManager;
     private static OlmOutboundGroupSession mAliceOutboundGroupSession;
@@ -158,27 +159,26 @@ public class OlmGroupSessionTest {
         OlmOutboundGroupSession outboundGroupSessionRef=null;
         OlmOutboundGroupSession outboundGroupSessionSerial=null;
 
-        // alice creates OUTBOUND GROUP SESSION
+        // create one OUTBOUND GROUP SESSION
         try {
             outboundGroupSessionRef = new OlmOutboundGroupSession();
         } catch (OlmException e) {
             assertTrue("Exception in OlmOutboundGroupSession, Exception code=" + e.getExceptionCode(), false);
         }
-
         assertNotNull(outboundGroupSessionRef);
 
 
         // serialize alice session
         Context context = getInstrumentation().getContext();
         try {
-            FileOutputStream fileOutput = context.openFileOutput(FILE_NAME_SERIAL_SESSION, Context.MODE_PRIVATE);
+            FileOutputStream fileOutput = context.openFileOutput(FILE_NAME_SERIAL_OUT_SESSION, Context.MODE_PRIVATE);
             ObjectOutputStream objectOutput = new ObjectOutputStream(fileOutput);
             objectOutput.writeObject(outboundGroupSessionRef);
             objectOutput.flush();
             objectOutput.close();
 
             // deserialize session
-            FileInputStream fileInput = context.openFileInput(FILE_NAME_SERIAL_SESSION);
+            FileInputStream fileInput = context.openFileInput(FILE_NAME_SERIAL_OUT_SESSION);
             ObjectInputStream objectInput = new ObjectInputStream(fileInput);
             outboundGroupSessionSerial = (OlmOutboundGroupSession) objectInput.readObject();
             objectInput.close();
@@ -204,6 +204,9 @@ public class OlmGroupSessionTest {
 
             // session IDs comparison
             assertTrue(sessionIdRef.equals(sessionIdSerial));
+
+            outboundGroupSessionRef.releaseSession();
+            outboundGroupSessionSerial.releaseSession();
         }
         catch (FileNotFoundException e) {
             Log.e(LOG_TAG, "## test03SessionSerialization(): Exception FileNotFoundException Msg=="+e.getMessage());
@@ -223,5 +226,78 @@ public class OlmGroupSessionTest {
 
     }
 
+    @Test
+    public void test15SerializeInboundSession() {
+        OlmOutboundGroupSession aliceOutboundGroupSession=null;
+        OlmInboundGroupSession bobInboundGroupSessionRef=null;
+        OlmInboundGroupSession bobInboundGroupSessionSerial=null;
+
+        // alice creates OUTBOUND GROUP SESSION
+        try {
+            aliceOutboundGroupSession = new OlmOutboundGroupSession();
+        } catch (OlmException e) {
+            assertTrue("Exception in OlmOutboundGroupSession, Exception code=" + e.getExceptionCode(), false);
+        }
+        assertNotNull(aliceOutboundGroupSession);
+
+        // get the session key from the outbound group session
+        String sessionKeyRef = aliceOutboundGroupSession.sessionKey();
+        assertNotNull(sessionKeyRef);
+
+        // bob creates INBOUND GROUP SESSION
+        try {
+            bobInboundGroupSessionRef = new OlmInboundGroupSession(sessionKeyRef);
+        } catch (OlmException e) {
+            assertTrue("Exception in OlmInboundGroupSession, Exception code=" + e.getExceptionCode(), false);
+        }
+        assertNotNull(bobInboundGroupSessionRef);
+
+
+        // serialize alice session
+        Context context = getInstrumentation().getContext();
+        try {
+            FileOutputStream fileOutput = context.openFileOutput(FILE_NAME_SERIAL_IN_SESSION, Context.MODE_PRIVATE);
+            ObjectOutputStream objectOutput = new ObjectOutputStream(fileOutput);
+            objectOutput.writeObject(bobInboundGroupSessionRef);
+            objectOutput.flush();
+            objectOutput.close();
+
+            // deserialize session
+            FileInputStream fileInput = context.openFileInput(FILE_NAME_SERIAL_OUT_SESSION);
+            ObjectInputStream objectInput = new ObjectInputStream(fileInput);
+            bobInboundGroupSessionSerial = (OlmInboundGroupSession)objectInput.readObject();
+            objectInput.close();
+
+            // get sessions IDs
+            String aliceSessionId = aliceOutboundGroupSession.sessionIdentifier();
+            String sessionIdRef = bobInboundGroupSessionRef.sessionIdentifier();
+            String sessionIdSerial = bobInboundGroupSessionSerial.sessionIdentifier();
+
+            // session ID sanity check
+            assertFalse(TextUtils.isEmpty(aliceSessionId));
+            assertFalse(TextUtils.isEmpty(sessionIdRef));
+            assertFalse(TextUtils.isEmpty(sessionIdSerial));
+
+            // session IDs comparison
+            assertTrue(aliceSessionId.equals(sessionIdSerial));
+            assertTrue(sessionIdRef.equals(sessionIdSerial));
+        }
+        catch (FileNotFoundException e) {
+            Log.e(LOG_TAG, "## test03SessionSerialization(): Exception FileNotFoundException Msg=="+e.getMessage());
+        }
+        catch (ClassNotFoundException e) {
+            Log.e(LOG_TAG, "## test03SessionSerialization(): Exception ClassNotFoundException Msg==" + e.getMessage());
+        }
+        catch (IOException e) {
+            Log.e(LOG_TAG, "## test03SessionSerialization(): Exception IOException Msg==" + e.getMessage());
+        }
+        /*catch (OlmException e) {
+            Log.e(LOG_TAG, "## test03SessionSerialization(): Exception OlmException Msg==" + e.getMessage());
+        }*/
+        catch (Exception e) {
+            Log.e(LOG_TAG, "## test03SessionSerialization(): Exception Msg==" + e.getMessage());
+        }
+
+    }
 
 }
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmAccount.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmAccount.java
index 8d19a0c..2381585 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmAccount.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmAccount.java
@@ -26,7 +26,6 @@ import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
-import java.util.Random;
 
 public class OlmAccount implements Serializable {
     private static final long serialVersionUID = 3497486121598434824L;
@@ -52,7 +51,7 @@ public class OlmAccount implements Serializable {
     /** account raw pointer value (OlmAccount*) returned by JNI.
      * this value identifies uniquely the native account instance.
      */
-    private transient long mNativeOlmAccountId;
+    private transient long mNativeId;
 
 
     public OlmAccount() throws OlmException {
@@ -179,7 +178,7 @@ public class OlmAccount implements Serializable {
      * @return native account ID
      */
     public long getOlmAccountId(){
-        return mNativeOlmAccountId;
+        return mNativeId;
     }
 
     /**
@@ -189,7 +188,7 @@ public class OlmAccount implements Serializable {
     public void releaseAccount(){
         releaseAccountJni();
 
-        mNativeOlmAccountId = 0;
+        mNativeId = 0;
     }
 
     /**
@@ -208,7 +207,7 @@ public class OlmAccount implements Serializable {
      */
     private boolean initNewAccount() {
         boolean retCode = false;
-        if(0 != (mNativeOlmAccountId = initNewAccountJni())){
+        if(0 != (mNativeId = initNewAccountJni())){
             retCode = true;
         }
         return retCode;
@@ -217,7 +216,7 @@ public class OlmAccount implements Serializable {
     /**
      * Create and initialize an OLM account in native side.<br>
      * Do not forget to call {@link #releaseAccount()} when JAVA side is done.
-     * @return native account instance identifier (see {@link #mNativeOlmAccountId})
+     * @return native account instance identifier (see {@link #mNativeId})
      */
     private native long initNewAccountJni();
 
@@ -230,7 +229,7 @@ public class OlmAccount implements Serializable {
      */
     private boolean createNewAccount() {
         boolean retCode = false;
-        if(0 != (mNativeOlmAccountId = createNewAccountJni())){
+        if(0 != (mNativeId = createNewAccountJni())){
             retCode = true;
         }
         return retCode;
@@ -239,7 +238,7 @@ public class OlmAccount implements Serializable {
     /**
      * Create an OLM account in native side.<br>
      * Do not forget to call {@link #releaseAccount()} when JAVA side is done.
-     * @return native account instance identifier (see {@link #mNativeOlmAccountId})
+     * @return native account instance identifier (see {@link #mNativeId})
      */
     private native long createNewAccountJni();
 
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmException.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmException.java
index d74f6e3..fe43f94 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmException.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmException.java
@@ -33,6 +33,8 @@ public class OlmException extends Exception {
     public static final int EXCEPTION_CODE_INIT_SESSION_CREATION = 9;
     public static final int EXCEPTION_CODE_OUTBOUND_GROUP_SESSION_SERIALIZATION = 10;
     public static final int EXCEPTION_CODE_OUTBOUND_GROUP_SESSION_DESERIALIZATION = 11;
+    public static final int EXCEPTION_CODE_INBOUND_GROUP_SESSION_SERIALIZATION = 12;
+    public static final int EXCEPTION_CODE_INBOUND_GROUP_SESSION_DESERIALIZATION = 13;
 
     // exception human readable messages
     public static final String EXCEPTION_MSG_NEW_OUTBOUND_GROUP_SESSION = "failed to create a new outbound group Session";
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmInboundGroupSession.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmInboundGroupSession.java
index e78e259..8d33b2c 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmInboundGroupSession.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmInboundGroupSession.java
@@ -23,6 +23,9 @@ package org.matrix.olm;
 import android.text.TextUtils;
 import android.util.Log;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.io.Serializable;
 
 public class OlmInboundGroupSession implements Serializable {
@@ -32,26 +35,18 @@ public class OlmInboundGroupSession implements Serializable {
     /** session raw pointer value returned by JNI.<br>
      * this value uniquely identifies the native inbound group session instance.
      */
-    private long mNativeOlmInboundGroupSessionId;
-
-    /**
-     * Getter on the native inbound group session ID.
-     * @return native inbound group session ID
-     */
-    public long getOlmInboundGroupSessionId() {
-        return mNativeOlmInboundGroupSessionId;
-    }
+    private transient long mNativeId;
 
     /**
      * Constructor.<br>
      * Create and save a new native session instance ID and start a new inbound group session.
      * The session key parameter is retrieved from an outbound group session
-     * See {@link #initNewSession()} and {@link #initInboundGroupSessionWithSessionKey(String)}
+     * See {@link #createNewSession()} and {@link #initInboundGroupSessionWithSessionKey(String)}
      * @param aSessionKey session key
      * @throws OlmException constructor failure
      */
     public OlmInboundGroupSession(String aSessionKey) throws OlmException {
-        if(initNewSession()) {
+        if(createNewSession()) {
             if( 0 != initInboundGroupSessionWithSessionKey(aSessionKey)) {
                 releaseSession();// prevent memory leak before throwing
                 throw new OlmException(OlmException.EXCEPTION_CODE_INIT_INBOUND_GROUP_SESSION,OlmException.EXCEPTION_MSG_INIT_INBOUND_GROUP_SESSION);
@@ -68,14 +63,14 @@ public class OlmInboundGroupSession implements Serializable {
     public void releaseSession(){
         releaseSessionJni();
 
-        mNativeOlmInboundGroupSessionId = 0;
+        mNativeId = 0;
     }
 
     /**
      * Destroy the corresponding OLM inbound group session native object.<br>
      * This method must ALWAYS be called when this JAVA instance
      * is destroyed (ie. garbage collected) to prevent memory leak in native side.
-     * See {@link #initNewSessionJni()}.
+     * See {@link #createNewSessionJni()}.
      */
     private native void releaseSessionJni();
 
@@ -84,9 +79,9 @@ public class OlmInboundGroupSession implements Serializable {
      * To be called before any other API call.
      * @return true if init succeed, false otherwise.
      */
-    private boolean initNewSession() {
+    private boolean createNewSession() {
         boolean retCode = false;
-        if(0 != (mNativeOlmInboundGroupSessionId = initNewSessionJni())){
+        if(0 != (mNativeId = createNewSessionJni())){
             retCode = true;
         }
         return retCode;
@@ -95,13 +90,13 @@ public class OlmInboundGroupSession implements Serializable {
     /**
      * Create the corresponding OLM inbound group session in native side.<br>
      * Do not forget to call {@link #releaseSession()} when JAVA side is done.
-     * @return native session instance identifier (see {@link #mNativeOlmInboundGroupSessionId})
+     * @return native session instance identifier (see {@link #mNativeId})
      */
-    private native long initNewSessionJni();
+    private native long createNewSessionJni();
 
     /**
      * Start a new inbound group session.<br>
-     * The session key parameter is retrieved from a outbound group session
+     * The session key parameter is retrieved from an outbound group session
      * see {@link OlmOutboundGroupSession#sessionKey()}
      * @param aSessionKey session key
      * @return 0 if operation succeed, -1 otherwise
@@ -132,8 +127,128 @@ public class OlmInboundGroupSession implements Serializable {
     private native String decryptMessageJni(String aEncryptedMsg);
 
 
-    // TODO missing API: initWithSerializedData
-    // TODO missing API: serializeDataWithKey
-    // TODO missing API: initWithCoder
-    // TODO missing API: encodeWithCoder
+    /**
+     * Kick off the serialization mechanism.
+     * @param aOutStream output stream for serializing
+     * @throws IOException
+     * @throws OlmException
+     */
+    private void writeObject(ObjectOutputStream aOutStream) throws IOException, OlmException {
+        aOutStream.defaultWriteObject();
+
+        // generate serialization key
+        String key = OlmUtility.getRandomKey();
+
+        // compute pickle string
+        StringBuffer errorMsg = new StringBuffer();
+        String pickledData = serializeDataWithKey(key, errorMsg);
+
+        if(null == pickledData) {
+            throw new OlmException(OlmException.EXCEPTION_CODE_INBOUND_GROUP_SESSION_SERIALIZATION, String.valueOf(errorMsg));
+        } else {
+            aOutStream.writeObject(key);
+            aOutStream.writeObject(pickledData);
+        }
+    }
+
+    /**
+     * Kick off the deserialization mechanism.
+     * @param aInStream
+     * @throws IOException
+     * @throws ClassNotFoundException
+     * @throws OlmException
+     */
+    private void readObject(ObjectInputStream aInStream) throws IOException, ClassNotFoundException, OlmException {
+        aInStream.defaultReadObject();
+        StringBuffer errorMsg = new StringBuffer();
+
+        String key = (String) aInStream.readObject();
+        String pickledData = (String) aInStream.readObject();
+
+        if(TextUtils.isEmpty(key)) {
+            throw new OlmException(OlmException.EXCEPTION_CODE_INBOUND_GROUP_SESSION_DESERIALIZATION, OlmException.EXCEPTION_MSG_INVALID_PARAMS_DESERIALIZATION+" key");
+
+        } else if(TextUtils.isEmpty(pickledData)) {
+            throw new OlmException(OlmException.EXCEPTION_CODE_INBOUND_GROUP_SESSION_DESERIALIZATION, OlmException.EXCEPTION_MSG_INVALID_PARAMS_DESERIALIZATION+" pickle");
+
+        } else if(!createNewSession()) {
+            throw new OlmException(OlmException.EXCEPTION_CODE_INBOUND_GROUP_SESSION_DESERIALIZATION, OlmException.EXCEPTION_MSG_INIT_NEW_ACCOUNT_DESERIALIZATION);
+
+        } else if(!initWithSerializedData(pickledData, key, errorMsg)) {
+            releaseSession(); // prevent memory leak
+            throw new OlmException(OlmException.EXCEPTION_CODE_INBOUND_GROUP_SESSION_DESERIALIZATION, String.valueOf(errorMsg));
+
+        } else {
+            Log.d(LOG_TAG,"## readObject(): success");
+        }
+    }
+
+    /**
+     * Return a session as a base64 string.<br>
+     * The account is serialized and encrypted with aKey.
+     * In case of failure, an error human readable
+     * description is provide in aErrorMsg.
+     * @param aKey encryption key
+     * @param aErrorMsg error message description
+     * @return pickled base64 string if operation succeed, null otherwise
+     */
+    private String serializeDataWithKey(String aKey, StringBuffer aErrorMsg) {
+        String pickleRetValue = null;
+
+        // sanity check
+        if(null == aErrorMsg) {
+            Log.e(LOG_TAG,"## serializeDataWithKey(): invalid parameter - aErrorMsg=null");
+        } else if(TextUtils.isEmpty(aKey)) {
+            aErrorMsg.append("Invalid input parameters in serializeDataWithKey()");
+        } else {
+            aErrorMsg.setLength(0);
+            pickleRetValue = serializeDataWithKeyJni(aKey, aErrorMsg);
+        }
+
+        return pickleRetValue;
+    }
+    /**
+     * JNI counter part of {@link #serializeDataWithKey(String, StringBuffer)}.
+     * @param aKey encryption key
+     * @param aErrorMsg error message description
+     * @return pickled base64 string if operation succeed, null otherwise
+     */
+    private native String serializeDataWithKeyJni(String aKey, StringBuffer aErrorMsg);
+
+
+    /**
+     * Loads an account from a pickled base64 string.<br>
+     * See {@link #serializeDataWithKey(String, StringBuffer)}
+     * @param aSerializedData pickled account in a base64 string format
+     * @param aKey key used to encrypted
+     * @param aErrorMsg error message description
+     * @return true if operation succeed, false otherwise
+     */
+    private boolean initWithSerializedData(String aSerializedData, String aKey, StringBuffer aErrorMsg) {
+        boolean retCode = false;
+        String jniError;
+
+        if(null == aErrorMsg) {
+            Log.e(LOG_TAG, "## initWithSerializedData(): invalid input error parameter");
+        } else {
+            aErrorMsg.setLength(0);
+
+            if (TextUtils.isEmpty(aSerializedData) || TextUtils.isEmpty(aKey)) {
+                Log.e(LOG_TAG, "## initWithSerializedData(): invalid input parameters");
+            } else if (null == (jniError = initWithSerializedDataJni(aSerializedData, aKey))) {
+                retCode = true;
+            } else {
+                aErrorMsg.append(jniError);
+            }
+        }
+
+        return retCode;
+    }
+    /**
+     * JNI counter part of {@link #initWithSerializedData(String, String, StringBuffer)}.
+     * @param aSerializedData pickled account in a base64 string format
+     * @param aKey key used to encrypted
+     * @return null if operation succeed, an error message if operation failed
+     */
+    private native String initWithSerializedDataJni(String aSerializedData, String aKey);
 }
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmOutboundGroupSession.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmOutboundGroupSession.java
index 7fdf405..94acbd0 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmOutboundGroupSession.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmOutboundGroupSession.java
@@ -32,25 +32,17 @@ public class OlmOutboundGroupSession implements Serializable {
     /** session raw pointer value returned by JNI.<br>
      * this value uniquely identifies the native inbound group session instance.
      */
-    private long mNativeOlmOutboundGroupSessionId;
-
-    /**
-     * Getter on the native outbound group session ID.
-     * @return native outbound group session ID
-     */
-    public long getOlmInboundGroupSessionId(){
-        return mNativeOlmOutboundGroupSessionId;
-    }
+    private transient long mNativeId;
 
     /**
      * Constructor.<br>
      * Create and save a new session native instance ID and
      * initialise a new outbound group session.<br>
-     * See {@link #initNewSession()} and {@link #initOutboundGroupSession()}
+     * See {@link #createNewSession()} and {@link #initOutboundGroupSession()}
      * @throws OlmException constructor failure
      */
     public OlmOutboundGroupSession() throws OlmException {
-        if(initNewSession()) {
+        if(createNewSession()) {
             if( 0 != initOutboundGroupSession()) {
                 releaseSession();// prevent memory leak before throwing
                 throw new OlmException(OlmException.EXCEPTION_CODE_INIT_OUTBOUND_GROUP_SESSION, OlmException.EXCEPTION_MSG_INIT_OUTBOUND_GROUP_SESSION);
@@ -104,7 +96,7 @@ public class OlmOutboundGroupSession implements Serializable {
         } else if(TextUtils.isEmpty(pickledData)) {
             throw new OlmException(OlmException.EXCEPTION_CODE_OUTBOUND_GROUP_SESSION_DESERIALIZATION, OlmException.EXCEPTION_MSG_INVALID_PARAMS_DESERIALIZATION+" pickle");
 
-        } else if(!initNewSession()) {
+        } else if(!createNewSession()) {
             throw new OlmException(OlmException.EXCEPTION_CODE_OUTBOUND_GROUP_SESSION_DESERIALIZATION, OlmException.EXCEPTION_MSG_INIT_NEW_ACCOUNT_DESERIALIZATION);
 
         } else if(!initWithSerializedData(pickledData, key, errorMsg)) {
@@ -180,26 +172,26 @@ public class OlmOutboundGroupSession implements Serializable {
      */
     public void releaseSession() {
         releaseSessionJni();        
-        mNativeOlmOutboundGroupSessionId = 0;
+        mNativeId = 0;
     }
 
     /**
      * Destroy the corresponding OLM outbound group session native object.<br>
      * This method must ALWAYS be called when this JAVA instance
      * is destroyed (ie. garbage collected) to prevent memory leak in native side.
-     * See {@link #initNewSessionJni()}.
+     * See {@link #createNewSessionJni()}.
      */
     private native void releaseSessionJni();
 
     /**
      * Create and save the session native instance ID.
-     * Wrapper for {@link #initNewSessionJni()}.<br>
+     * Wrapper for {@link #createNewSessionJni()}.<br>
      * To be called before any other API call.
      * @return true if init succeed, false otherwise.
      */
-    private boolean initNewSession() {
+    private boolean createNewSession() {
         boolean retCode = false;
-        if(0 != (mNativeOlmOutboundGroupSessionId = initNewSessionJni())){
+        if(0 != (mNativeId = createNewSessionJni())){
             retCode = true;
         }
         return retCode;
@@ -208,9 +200,9 @@ public class OlmOutboundGroupSession implements Serializable {
     /**
      * Create the corresponding OLM outbound group session in native side.<br>
      * Do not forget to call {@link #releaseSession()} when JAVA side is done.
-     * @return native session instance identifier (see {@link #mNativeOlmOutboundGroupSessionId})
+     * @return native session instance identifier (see {@link #mNativeId})
      */
-    private native long initNewSessionJni();
+    private native long createNewSessionJni();
 
     /**
      * Start a new outbound group session.<br>
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmSession.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmSession.java
index eaf6110..5877d24 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmSession.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmSession.java
@@ -31,7 +31,7 @@ public class OlmSession implements Serializable {
     /** session raw pointer value (OlmSession*) returned by JNI.
      * this value uniquely identifies the native session instance.
      **/
-    private transient long mNativeOlmSessionId;
+    private transient long mNativeId;
 
 
     public OlmSession() throws OlmException {
@@ -158,7 +158,7 @@ public class OlmSession implements Serializable {
      * @return native session ID
      */
     public long getOlmSessionId(){
-        return mNativeOlmSessionId;
+        return mNativeId;
     }
 
     /**
@@ -176,7 +176,7 @@ public class OlmSession implements Serializable {
     public void releaseSession(){
         releaseSessionJni();
 
-        mNativeOlmSessionId = 0;
+        mNativeId = 0;
     }
 
     /**
@@ -187,7 +187,7 @@ public class OlmSession implements Serializable {
      */
     private boolean initNewSession() {
         boolean retCode = false;
-        if(0 != (mNativeOlmSessionId = initNewSessionJni())){
+        if(0 != (mNativeId = initNewSessionJni())){
             retCode = true;
         }
         return retCode;
@@ -196,7 +196,7 @@ public class OlmSession implements Serializable {
     /**
      * Create the corresponding OLM session in native side.<br>
      * Do not forget to call {@link #releaseSession()} when JAVA side is done.
-     * @return native session instance identifier (see {@link #mNativeOlmSessionId})
+     * @return native session instance identifier (see {@link #mNativeId})
      */
     private native long initNewSessionJni();
 
@@ -210,7 +210,7 @@ public class OlmSession implements Serializable {
      */
     private boolean createNewSession() {
         boolean retCode = false;
-        if(0 != (mNativeOlmSessionId = createNewSessionJni())){
+        if(0 != (mNativeId = createNewSessionJni())){
             retCode = true;
         }
         return retCode;
@@ -219,7 +219,7 @@ public class OlmSession implements Serializable {
     /**
      * Create an OLM account in native side.<br>
      * Do not forget to call {@link #releaseSession()} when JAVA side is done.
-     * @return native account instance identifier (see {@link #mNativeOlmSessionId})
+     * @return native account instance identifier (see {@link #mNativeId})
      */
     private native long createNewSessionJni();
 
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmUtility.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmUtility.java
index 342d8eb..3bf65a8 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmUtility.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmUtility.java
@@ -19,7 +19,6 @@ package org.matrix.olm;
 import android.text.TextUtils;
 import android.util.Log;
 
-import java.io.Serializable;
 import java.util.Random;
 
 public class OlmUtility {
@@ -31,28 +30,20 @@ public class OlmUtility {
     /** raw pointer value returned by JNI.
      * this value uniquely identifies this utility instance.
      **/
-    private long mNativeOlmUtilityId;
+    private long mNativeId;
 
     public OlmUtility() {
         initUtility();
     }
 
     /**
-     * Getter on the session ID.
-     * @return native session ID
-     */
-    public long getOlmUtilityId(){
-        return mNativeOlmUtilityId;
-    }
-
-    /**
      * Create a native utility instance.
      * To be called before any other API call.
      * @return true if init succeed, false otherwise.
      */
     private boolean initUtility() {
         boolean retCode = false;
-        if(0 != (mNativeOlmUtilityId = initUtilityJni())){
+        if(0 != (mNativeId = initUtilityJni())){
             retCode = true;
         }
         return retCode;
@@ -65,7 +56,7 @@ public class OlmUtility {
      */
     public void releaseUtility(){
         releaseUtilityJni();
-        mNativeOlmUtilityId = 0;
+        mNativeId = 0;
     }
     private native void releaseUtilityJni();
 
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_account.cpp b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_account.cpp
index 1a1b360..baa7939 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_account.cpp
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_account.cpp
@@ -119,8 +119,7 @@ JNIEXPORT jlong OLM_ACCOUNT_FUNC_DEF(initNewAccountJni)(JNIEnv *env, jobject thi
             // create account
             accountRetCode = olm_create_account(accountPtr, (void*)randomBuffPtr, randomSize);
             if(accountRetCode == olm_error()) {
-                const char *errorMsgPtr = olm_account_last_error(accountPtr);
-                LOGE("## initNewAccount(): failure - account creation failed Msg=%s", errorMsgPtr);
+                LOGE("## initNewAccount(): failure - account creation failed Msg=%s", (const char *)olm_account_last_error(accountPtr));
              }
 
             LOGD("## initNewAccount(): success - OLM account created");
@@ -171,8 +170,7 @@ JNIEXPORT jbyteArray OLM_ACCOUNT_FUNC_DEF(identityKeysJni)(JNIEnv *env, jobject
         {   // retrieve key pairs in identityKeysBytesPtr
             keysResult = olm_account_identity_keys(accountPtr, identityKeysBytesPtr, identityKeysLength);
             if(keysResult == olm_error()) {
-                const char *errorMsgPtr = olm_account_last_error(accountPtr);
-                LOGE("## identityKeys(): failure - error getting identity keys Msg=%s",errorMsgPtr);
+                LOGE("## identityKeys(): failure - error getting identity keys Msg=%s",(const char *)olm_account_last_error(accountPtr));
             }
             else
             {   // allocate the byte array to be returned to java
@@ -253,8 +251,7 @@ JNIEXPORT jint OLM_ACCOUNT_FUNC_DEF(generateOneTimeKeys)(JNIEnv *env, jobject th
             // retrieve key pairs in keysBytesPtr
             result = olm_account_generate_one_time_keys(accountPtr, (size_t)aNumberOfKeys, (void*)randomBufferPtr, randomLength);
             if(result == olm_error()) {
-                const char *errorMsgPtr = olm_account_last_error(accountPtr);
-                LOGE("## generateOneTimeKeys(): failure - error generating one time keys Msg=%s",errorMsgPtr);
+                LOGE("## generateOneTimeKeys(): failure - error generating one time keys Msg=%s",(const char *)olm_account_last_error(accountPtr));
             }
             else
             {
@@ -302,8 +299,7 @@ JNIEXPORT jbyteArray OLM_ACCOUNT_FUNC_DEF(oneTimeKeysJni)(JNIEnv *env, jobject t
         {   // retrieve key pairs in keysBytesPtr
             keysResult = olm_account_one_time_keys(accountPtr, keysBytesPtr, keysLength);
             if(keysResult == olm_error()) {
-                const char *errorMsgPtr = olm_account_last_error(accountPtr);
-                LOGE("## oneTimeKeysJni(): failure - error getting one time keys Msg=%s",errorMsgPtr);
+                LOGE("## oneTimeKeysJni(): failure - error getting one time keys Msg=%s",(const char *)olm_account_last_error(accountPtr));
             }
             else
             {   // allocate the byte array to be returned to java
@@ -351,8 +347,7 @@ JNIEXPORT jint OLM_ACCOUNT_FUNC_DEF(removeOneTimeKeysForSessionJni)(JNIEnv *env,
         result = olm_remove_one_time_keys(accountPtr, sessionPtr);
         if(result == olm_error())
         {   // the account doesn't have any matching "one time keys"..
-            const char *errorMsgPtr = olm_account_last_error(accountPtr);
-            LOGW("## removeOneTimeKeysForSessionJni(): failure - removing one time keys Msg=%s",errorMsgPtr);
+            LOGW("## removeOneTimeKeysForSessionJni(): failure - removing one time keys Msg=%s",(const char *)olm_account_last_error(accountPtr));
 
             retCode = ERROR_CODE_NO_MATCHING_ONE_TIME_KEYS;
         }
@@ -386,8 +381,7 @@ JNIEXPORT jint OLM_ACCOUNT_FUNC_DEF(markOneTimeKeysAsPublishedJni)(JNIEnv *env,
         result = olm_account_mark_keys_as_published(accountPtr);
         if(result == olm_error())
         {
-            const char *errorMsgPtr = olm_account_last_error(accountPtr);
-            LOGW("## markOneTimeKeysAsPublishedJni(): failure - Msg=%s",errorMsgPtr);
+            LOGW("## markOneTimeKeysAsPublishedJni(): failure - Msg=%s",(const char *)olm_account_last_error(accountPtr));
             retCode = ERROR_CODE_KO;
         }
         else
@@ -448,8 +442,7 @@ JNIEXPORT jstring OLM_ACCOUNT_FUNC_DEF(signMessageJni)(JNIEnv *env, jobject thiz
                                              signatureLength);
                 if(resultSign == olm_error())
                 {
-                    const char *errorMsgPtr = olm_account_last_error(accountPtr);
-                    LOGE("## signMessageJni(): failure - error signing message Msg=%s",errorMsgPtr);
+                    LOGE("## signMessageJni(): failure - error signing message Msg=%s",(const char *)olm_account_last_error(accountPtr));
                 }
                 else
                 {
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.cpp b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.cpp
index d10a05b..810d62c 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.cpp
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.cpp
@@ -38,7 +38,7 @@ JNIEXPORT void OLM_INBOUND_GROUP_SESSION_FUNC_DEF(releaseSessionJni)(JNIEnv *env
     LOGD(" ## releaseSessionJni(): sessionPtr=%p",sessionPtr);
 
     size_t retCode = olm_clear_inbound_group_session(sessionPtr);
-    LOGD(" ## releaseSessionJni(): clear_inbound_group_session=%lu",retCode);
+    LOGI(" ## releaseSessionJni(): clear_inbound_group_session=%lu",retCode);
 
     LOGD(" ## releaseSessionJni(): free IN");
     free(sessionPtr);
@@ -52,26 +52,26 @@ JNIEXPORT void OLM_INBOUND_GROUP_SESSION_FUNC_DEF(releaseSessionJni)(JNIEnv *env
 * to make the cast (OlmInboundGroupSession* => jlong) platform independent.
 * @return the initialized OlmInboundGroupSession* instance if init succeed, NULL otherwise
 **/
-JNIEXPORT jlong OLM_INBOUND_GROUP_SESSION_FUNC_DEF(initNewSessionJni)(JNIEnv *env, jobject thiz)
+JNIEXPORT jlong OLM_INBOUND_GROUP_SESSION_FUNC_DEF(createNewSessionJni)(JNIEnv *env, jobject thiz)
 {
     OlmInboundGroupSession* sessionPtr = NULL;
     size_t sessionSize = 0;
 
-    LOGD("## initNewSessionJni(): inbound group session IN");
+    LOGD("## createNewSessionJni(): inbound group session IN");
     sessionSize = olm_inbound_group_session_size();
 
     if(0 == sessionSize)
     {
-        LOGE(" ## initNewSessionJni(): failure - inbound group session size = 0");
+        LOGE(" ## createNewSessionJni(): failure - inbound group session size = 0");
     }
     else if(NULL != (sessionPtr=(OlmInboundGroupSession*)malloc(sessionSize)))
     {
       sessionPtr = olm_inbound_group_session(sessionPtr);
-      LOGD(" ## initNewSessionJni(): success - inbound group session size=%lu",sessionSize);
+      LOGD(" ## createNewSessionJni(): success - inbound group session size=%lu",sessionSize);
     }
     else
     {
-      LOGE(" ## initNewSessionJni(): failure - inbound group session OOM");
+      LOGE(" ## createNewSessionJni(): failure - inbound group session OOM");
     }
 
     return (jlong)(intptr_t)sessionPtr;
@@ -160,8 +160,7 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIEn
             size_t result = olm_inbound_group_session_id(sessionPtr, sessionIdPtr, lengthSessionId);
             if (result == olm_error())
             {
-                const char *errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
-                LOGE(" ## sessionIdentifierJni(): failure - get inbound group session identifier failure Msg=%s",errorMsgPtr);
+                LOGE(" ## sessionIdentifierJni(): failure - get inbound group session identifier failure Msg=%s",(const char *)olm_inbound_group_session_last_error(sessionPtr));
             }
             else
             {
@@ -221,8 +220,7 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
                                                                                encryptedMsgLength);
             if(maxPlainTextLength == olm_error())
             {
-                const char *errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
-                LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt_max_plaintext_length Msg=%s",errorMsgPtr);
+                LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt_max_plaintext_length Msg=%s",(const char *)olm_inbound_group_session_last_error(sessionPtr));
             }
             else
             {
@@ -240,8 +238,7 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
                                                            maxPlainTextLength);
                 if(plaintextLength == olm_error())
                 {
-                    const char *errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
-                    LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt Msg=%s",errorMsgPtr);
+                    LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt Msg=%s",(const char *)olm_inbound_group_session_last_error(sessionPtr));
                 }
                 else
                 {
@@ -275,4 +272,165 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
 }
 
 
+/**
+* Serialize and encrypt session instance into a base64 string.<br>
+* @param aKey key used to encrypt the serialized session data
+* @param[out] aErrorMsg error message set if operation failed
+* @return a base64 string if operation succeed, null otherwise
+**/
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(serializeDataWithKeyJni)(JNIEnv *env, jobject thiz, jstring aKey, jobject aErrorMsg)
+{
+    jstring pickledDataRetValue = 0;
+    jclass errorMsgJClass = 0;
+    jmethodID errorMsgMethodId = 0;
+    jstring errorJstring = 0;
+    const char *keyPtr = NULL;
+    void *pickledPtr = NULL;
+    OlmInboundGroupSession* sessionPtr = NULL;
+
+    LOGD("## inbound group session serializeDataWithKeyJni(): IN");
+
+    if(NULL == (sessionPtr = (OlmInboundGroupSession*)getInboundGroupSessionInstanceId(env,thiz)))
+    {
+        LOGE(" ## serializeDataWithKeyJni(): failure - invalid session ptr");
+    }
+    else if(0 == aKey)
+    {
+        LOGE(" ## serializeDataWithKeyJni(): failure - invalid key");
+    }
+    else if(0 == aErrorMsg)
+    {
+        LOGE(" ## serializeDataWithKeyJni(): failure - invalid error object");
+    }
+    else if(0 == (errorMsgJClass = env->GetObjectClass(aErrorMsg)))
+    {
+        LOGE(" ## serializeDataWithKeyJni(): failure - unable to get error class");
+    }
+    else if(0 == (errorMsgMethodId = env->GetMethodID(errorMsgJClass, "append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;")))
+    {
+        LOGE(" ## serializeDataWithKeyJni(): failure - unable to get error method ID");
+    }
+    else if(NULL == (keyPtr = env->GetStringUTFChars(aKey, 0)))
+    {
+        LOGE(" ## serializeDataWithKeyJni(): failure - keyPtr JNI allocation OOM");
+    }
+    else
+    {
+        size_t pickledLength = olm_pickle_inbound_group_session_length(sessionPtr);
+        size_t keyLength = (size_t)env->GetStringUTFLength(aKey);
+        LOGD(" ## serializeDataWithKeyJni(): pickledLength=%lu keyLength=%lu",pickledLength, keyLength);
+        LOGD(" ## serializeDataWithKeyJni(): key=%s",(char const *)keyPtr);
+
+        if(NULL == (pickledPtr = (void*)malloc((pickledLength+1)*sizeof(uint8_t))))
+        {
+            LOGE(" ## serializeDataWithKeyJni(): failure - pickledPtr buffer OOM");
+        }
+        else
+        {
+            size_t result = olm_pickle_inbound_group_session(sessionPtr,
+                                                             (void const *)keyPtr,
+                                                              keyLength,
+                                                              (void*)pickledPtr,
+                                                              pickledLength);
+            if(result == olm_error())
+            {
+                const char *errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
+                LOGE(" ## serializeDataWithKeyJni(): failure - olm_pickle_outbound_group_session() Msg=%s",errorMsgPtr);
+
+                if(0 != (errorJstring = env->NewStringUTF(errorMsgPtr)))
+                {
+                    env->CallObjectMethod(aErrorMsg, errorMsgMethodId, errorJstring);
+                }
+            }
+            else
+            {
+                // build success output
+                (static_cast<char*>(pickledPtr))[pickledLength] = static_cast<char>('\0');
+                pickledDataRetValue = env->NewStringUTF((const char*)pickledPtr);
+                LOGD(" ## serializeDataWithKeyJni(): success - result=%lu pickled=%s", result, static_cast<char*>(pickledPtr));
+            }
+        }
+    }
+
+    // free alloc
+    if(NULL != keyPtr)
+    {
+     env->ReleaseStringUTFChars(aKey, keyPtr);
+    }
+
+    if(NULL != pickledPtr)
+    {
+        free(pickledPtr);
+    }
+
+    return pickledDataRetValue;
+}
+
+
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(initWithSerializedDataJni)(JNIEnv *env, jobject thiz, jstring aSerializedData, jstring aKey)
+{
+    OlmInboundGroupSession* sessionPtr = NULL;
+    jstring errorMessageRetValue = 0;
+    const char *keyPtr = NULL;
+    const char *pickledPtr = NULL;
 
+    LOGD("## initWithSerializedDataJni(): IN");
+
+    if(NULL == (sessionPtr = (OlmInboundGroupSession*)getInboundGroupSessionInstanceId(env,thiz)))
+    {
+        LOGE(" ## initWithSerializedDataJni(): failure - session failure OOM");
+    }
+    else if(0 == aKey)
+    {
+        LOGE(" ## initWithSerializedDataJni(): failure - invalid key");
+    }
+    else if(0 == aSerializedData)
+    {
+        LOGE(" ## initWithSerializedDataJni(): failure - serialized data");
+    }
+    else if(NULL == (keyPtr = env->GetStringUTFChars(aKey, 0)))
+    {
+        LOGE(" ## initWithSerializedDataJni(): failure - keyPtr JNI allocation OOM");
+    }
+    else if(NULL == (pickledPtr = env->GetStringUTFChars(aSerializedData, 0)))
+    {
+        LOGE(" ## initWithSerializedDataJni(): failure - pickledPtr JNI allocation OOM");
+    }
+    else
+    {
+        size_t pickledLength = (size_t)env->GetStringUTFLength(aSerializedData);
+        size_t keyLength = (size_t)env->GetStringUTFLength(aKey);
+        LOGD(" ## initWithSerializedDataJni(): pickledLength=%lu keyLength=%lu",pickledLength, keyLength);
+        LOGD(" ## initWithSerializedDataJni(): key=%s",(char const *)keyPtr);
+        LOGD(" ## initWithSerializedDataJni(): pickled=%s",(char const *)pickledPtr);
+
+        size_t result = olm_unpickle_inbound_group_session(sessionPtr,
+                                                           (void const *)keyPtr,
+                                                           keyLength,
+                                                           (void*)pickledPtr,
+                                                           pickledLength);
+        if(result == olm_error())
+        {
+            const char *errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
+            LOGE(" ## initWithSerializedDataJni(): failure - olm_unpickle_inbound_group_session() Msg=%s",errorMsgPtr);
+            errorMessageRetValue = env->NewStringUTF(errorMsgPtr);
+        }
+        else
+        {
+            LOGD(" ## initWithSerializedDataJni(): success - result=%lu ", result);
+        }
+    }
+
+    // free alloc
+    if(NULL != keyPtr)
+    {
+        env->ReleaseStringUTFChars(aKey, keyPtr);
+    }
+
+    if(NULL != pickledPtr)
+    {
+        env->ReleaseStringUTFChars(aSerializedData, pickledPtr);
+    }
+
+    return errorMessageRetValue;
+}
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.h b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.h
index 1eb8238..897ef46 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.h
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.h
@@ -29,12 +29,16 @@ extern "C" {
 
 // session creation/destruction
 JNIEXPORT void OLM_INBOUND_GROUP_SESSION_FUNC_DEF(releaseSessionJni)(JNIEnv *env, jobject thiz);
-JNIEXPORT jlong OLM_INBOUND_GROUP_SESSION_FUNC_DEF(initNewSessionJni)(JNIEnv *env, jobject thiz);
+JNIEXPORT jlong OLM_INBOUND_GROUP_SESSION_FUNC_DEF(createNewSessionJni)(JNIEnv *env, jobject thiz);
 
 JNIEXPORT jint OLM_INBOUND_GROUP_SESSION_FUNC_DEF(initInboundGroupSessionWithSessionKeyJni)(JNIEnv *env, jobject thiz, jstring aSessionKey);
 JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIEnv *env, jobject thiz);
 JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg);
 
+// serialization
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(serializeDataWithKeyJni)(JNIEnv *env, jobject thiz, jstring aKey, jobject aErrorMsg);
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(initWithSerializedDataJni)(JNIEnv *env, jobject thiz, jstring aSerializedData, jstring aKey);
+
 
 #ifdef __cplusplus
 }
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni.h b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni.h
index 2e31bff..bb718b6 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni.h
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni.h
@@ -30,16 +30,15 @@
 /* logging macros */
 #define ENABLE_LOGS
 
+#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__)
+#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
+
 #ifdef ENABLE_LOGS
-    #define LOGV(...) __android_log_print(ANDROID_LOG_VERBOSE, TAG, __VA_ARGS__)
     #define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)
     #define LOGW(...) __android_log_print(ANDROID_LOG_WARN, TAG, __VA_ARGS__)
-    #define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__)
 #else
-    #define LOGV(...)
     #define LOGD(...)
     #define LOGW(...)
-    #define LOGE(...)
 #endif
 
 #define FUNC_DEF(class_name,func_name) JNICALL Java_org_matrix_olm_##class_name##_##func_name
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni_helper.cpp b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni_helper.cpp
index 174739c..1f0c0df 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni_helper.cpp
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni_helper.cpp
@@ -63,12 +63,13 @@ bool setRandomInBuffer(uint8_t **aBuffer2Ptr, size_t aRandomSize)
 
 
 /**
-* Read the account instance ID of the calling object.
+* Read the instance ID of the calling object.
 * @param aJniEnv pointer pointing on the JNI function table
 * @param aJavaObject reference to the object on which the method is invoked
+* @param aCallingClass java calling clas name
 * @return the instance ID if operation succeed, -1 if instance ID was not found.
 **/
-jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
+jlong getInstanceId(JNIEnv* aJniEnv, jobject aJavaObject, const char *aCallingClass)
 {
   jlong instanceId = 0;
   jfieldID instanceIdField;
@@ -77,7 +78,7 @@ jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
   if(NULL!=aJniEnv)
   {
-    requiredClass = aJniEnv->FindClass(CLASS_OLM_ACCOUNT);
+    requiredClass = aJniEnv->FindClass(aCallingClass);
 
     if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
     {
@@ -85,78 +86,56 @@ jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
     }
     else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
     {
-      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmAccountId", "J")))
+      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeId", "J")))
       {
         instanceId = aJniEnv->GetLongField(aJavaObject, instanceIdField);
         aJniEnv->DeleteLocalRef(loaderClass);
-        LOGD("## getAccountInstanceId(): read from java instanceId=%lld",instanceId);
+        LOGD("## getInstanceId(): read from java instanceId=%lld",instanceId);
       }
       else
       {
-        LOGE("## getAccountInstanceId() ERROR! GetFieldID=null");
+        LOGE("## getInstanceId() ERROR! GetFieldID=null");
       }
     }
     else
     {
-      LOGE("## getAccountInstanceId() ERROR! GetObjectClass=null");
+      LOGE("## getInstanceId() ERROR! GetObjectClass=null");
     }
   }
   else
   {
-    LOGE("## getAccountInstanceId() ERROR! aJniEnv=NULL");
+    LOGE("## getInstanceId() ERROR! aJniEnv=NULL");
   }
-  LOGD("## getAccountInstanceId() success - instanceId=%p (jlong)(intptr_t)instanceId=%lld",(void*)instanceId, (jlong)(intptr_t)instanceId);
+  LOGD("## getInstanceId() success - instanceId=%p (jlong)(intptr_t)instanceId=%lld",(void*)instanceId, (jlong)(intptr_t)instanceId);
   return instanceId;
 }
 
 /**
-* Read the session instance ID of the calling object (aJavaObject).<br>
+* Read the account instance ID of the calling object.
 * @param aJniEnv pointer pointing on the JNI function table
 * @param aJavaObject reference to the object on which the method is invoked
-* @return the instance ID if read succeed, -1 otherwise.
+* @return the instance ID if operation succeed, -1 if instance ID was not found.
 **/
-jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
+jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId = 0;
-  jfieldID instanceIdField;
-  jclass loaderClass;
-  jclass requiredClass = 0;
+  jlong instanceId = getInstanceId(aJniEnv, aJavaObject, CLASS_OLM_ACCOUNT);
+  return instanceId;
+}
 
-  if(NULL!=aJniEnv)
-  {
-    requiredClass = aJniEnv->FindClass(CLASS_OLM_SESSION);
 
-    if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
-    {
-        LOGE("## getSessionInstanceId() failure - invalid instance of");
-    }
-    else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
-    {
-      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmSessionId", "J")))
-      {
-        instanceId = aJniEnv->GetLongField(aJavaObject, instanceIdField);
-        aJniEnv->DeleteLocalRef(loaderClass);
-      }
-      else
-      {
-        LOGE("## getSessionInstanceId() ERROR! GetFieldID=null");
-      }
-    }
-    else
-    {
-      LOGE("## getSessionInstanceId() ERROR! GetObjectClass=null");
-    }
-  }
-  else
-  {
-    LOGE("## getSessionInstanceId() ERROR! aJniEnv=NULL");
-  }
 
-  //LOGD("## getSessionInstanceId() success - instanceId=%lld",instanceId);
+/**
+* Read the session instance ID of the calling object (aJavaObject).<br>
+* @param aJniEnv pointer pointing on the JNI function table
+* @param aJavaObject reference to the object on which the method is invoked
+* @return the instance ID if read succeed, -1 otherwise.
+**/
+jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
+{
+  jlong instanceId = getInstanceId(aJniEnv, aJavaObject, CLASS_OLM_SESSION);
   return instanceId;
 }
 
-
 /**
 * Read the inbound group session instance ID of the calling object (aJavaObject).<br>
 * @param aJniEnv pointer pointing on the JNI function table
@@ -165,41 +144,7 @@ jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 **/
 jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId = 0;
-  jfieldID instanceIdField;
-  jclass loaderClass;
-  jclass requiredClass = 0;
-
-  if(NULL!=aJniEnv)
-  {
-    requiredClass = aJniEnv->FindClass(CLASS_OLM_INBOUND_GROUP_SESSION);
-
-    if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
-    {
-      LOGE("## getInboundGroupSessionInstanceId() failure - invalid instance of");
-    }
-    else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
-    {
-      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmInboundGroupSessionId", "J")))
-      {
-        instanceId = aJniEnv->GetLongField(aJavaObject, instanceIdField);
-        aJniEnv->DeleteLocalRef(loaderClass);
-      }
-      else
-      {
-        LOGE("## getInboundGroupSessionInstanceId() ERROR! GetFieldID=null");
-      }
-    }
-    else
-    {
-      LOGE("## getInboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
-    }
-  }
-  else
-  {
-    LOGE("## getInboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
-  }
-
+  jlong instanceId = getInstanceId(aJniEnv, aJavaObject, CLASS_OLM_INBOUND_GROUP_SESSION);
   return instanceId;
 }
 
@@ -212,84 +157,23 @@ jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 **/
 jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId = 0;
-  jfieldID instanceIdField;
-  jclass loaderClass;
-  jclass requiredClass = 0;
-
-  if(NULL!=aJniEnv)
-  {
-    requiredClass = aJniEnv->FindClass(CLASS_OLM_OUTBOUND_GROUP_SESSION);
-
-    if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
-    {
-        LOGE("## getOutboundGroupSessionInstanceId() failure - invalid instance of");
-    }
-    else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
-    {
-      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmOutboundGroupSessionId", "J")))
-      {
-        instanceId = aJniEnv->GetLongField(aJavaObject, instanceIdField);
-        aJniEnv->DeleteLocalRef(loaderClass);
-      }
-      else
-      {
-        LOGE("## getOutboundGroupSessionInstanceId() ERROR! GetFieldID=null");
-      }
-    }
-    else
-    {
-      LOGE("## getOutboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
-    }
-  }
-  else
-  {
-    LOGE("## getOutboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
-  }
-
+  jlong instanceId = getInstanceId(aJniEnv, aJavaObject, CLASS_OLM_OUTBOUND_GROUP_SESSION);
   return instanceId;
 }
 
+/**
+* Read the utility instance ID of the calling object (aJavaObject).<br>
+* @param aJniEnv pointer pointing on the JNI function table
+* @param aJavaObject reference to the object on which the method is invoked
+* @return the instance ID if read succeed, -1 otherwise.
+**/
 jlong getUtilityInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId = 0;
-  jfieldID instanceIdField;
-  jclass loaderClass;
-  jclass requiredClass = 0;
-
-  if(NULL!=aJniEnv)
-  {
-    requiredClass = aJniEnv->FindClass(CLASS_OLM_UTILITY);
-
-    if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
-    {
-        LOGE("## getUtilityInstanceId() failure - invalid instance of");
-    }
-    else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
-    {
-      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmUtilityId", "J")))
-      {
-        instanceId = aJniEnv->GetLongField(aJavaObject, instanceIdField);
-        aJniEnv->DeleteLocalRef(loaderClass);
-      }
-      else
-      {
-        LOGE("## getUtilityInstanceId() ERROR! GetFieldID=null");
-      }
-    }
-    else
-    {
-      LOGE("## getUtilityInstanceId() ERROR! GetObjectClass=null");
-    }
-  }
-  else
-  {
-    LOGE("## getUtilityInstanceId() ERROR! aJniEnv=NULL");
-  }
-
+  jlong instanceId = getInstanceId(aJniEnv, aJavaObject, CLASS_OLM_UTILITY);
   return instanceId;
 }
 
+
 template <typename T>
 jstring serializeDataWithKey(JNIEnv *env, jobject thiz,
                                 jstring aKey,
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.cpp b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.cpp
index 67bf8bd..8ccd78e 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.cpp
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.cpp
@@ -38,7 +38,7 @@ JNIEXPORT void OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(releaseSessionJni)(JNIEnv *en
     LOGD(" ## releaseSessionJni(): sessionPtr=%p",sessionPtr);
 
     size_t retCode = olm_clear_outbound_group_session(sessionPtr);
-    LOGD(" ## releaseSessionJni(): clear_outbound_group_session=%lu",retCode);
+    LOGI(" ## releaseSessionJni(): clear_outbound_group_session=%lu",retCode);
 
     LOGD(" ## releaseSessionJni(): free IN");
     free(sessionPtr);
@@ -52,26 +52,26 @@ JNIEXPORT void OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(releaseSessionJni)(JNIEnv *en
 * to make the cast (OlmOutboundGroupSession* => jlong) platform independent.
 * @return the initialized OlmOutboundGroupSession* instance if init succeed, NULL otherwise
 **/
-JNIEXPORT jlong OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(initNewSessionJni)(JNIEnv *env, jobject thiz)
+JNIEXPORT jlong OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(createNewSessionJni)(JNIEnv *env, jobject thiz)
 {
     OlmOutboundGroupSession* sessionPtr = NULL;
     size_t sessionSize = 0;
 
-    LOGD("## initNewSessionJni(): outbound group session IN");
+    LOGD("## createNewSessionJni(): outbound group session IN");
     sessionSize = olm_outbound_group_session_size();
 
     if(0 == sessionSize)
     {
-        LOGE(" ## initNewSessionJni(): failure - outbound group session size = 0");
+        LOGE(" ## createNewSessionJni(): failure - outbound group session size = 0");
     }
     else if(NULL != (sessionPtr=(OlmOutboundGroupSession*)malloc(sessionSize)))
     {
       sessionPtr = olm_outbound_group_session(sessionPtr);
-      LOGD(" ## initNewSessionJni(): success - outbound group session size=%lu",sessionSize);
+      LOGD(" ## createNewSessionJni(): success - outbound group session size=%lu",sessionSize);
     }
     else
     {
-      LOGE(" ## initNewSessionJni(): failure - outbound group session OOM");
+      LOGE(" ## createNewSessionJni(): failure - outbound group session OOM");
     }
 
     return (jlong)(intptr_t)sessionPtr;
@@ -111,8 +111,7 @@ JNIEXPORT jint OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(initOutboundGroupSessionJni)(
 
             size_t sessionResult = olm_init_outbound_group_session(sessionPtr, randomBuffPtr, randomLength);
             if(sessionResult == olm_error()) {
-                const char *errorMsgPtr = olm_outbound_group_session_last_error(sessionPtr);
-                LOGE(" ## initOutboundGroupSessionJni(): failure - init outbound session creation  Msg=%s",errorMsgPtr);
+                LOGE(" ## initOutboundGroupSessionJni(): failure - init outbound session creation  Msg=%s",(const char *)olm_outbound_group_session_last_error(sessionPtr));
             }
             else
             {
@@ -160,8 +159,7 @@ JNIEXPORT jstring OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIE
             size_t result = olm_outbound_group_session_id(sessionPtr, sessionIdPtr, lengthSessionId);
             if (result == olm_error())
             {
-                const char *errorMsgPtr = olm_outbound_group_session_last_error(sessionPtr);
-                LOGE(" ## sessionIdentifierJni(): failure - outbound group session identifier failure Msg=%s",errorMsgPtr);
+                LOGE(" ## sessionIdentifierJni(): failure - outbound group session identifier failure Msg=%s",(const char *)olm_outbound_group_session_last_error(sessionPtr));
             }
             else
             {
@@ -237,8 +235,7 @@ JNIEXPORT jstring OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(sessionKeyJni)(JNIEnv *env
             size_t result = olm_outbound_group_session_key(sessionPtr, sessionKeyPtr, sessionKeyLength);
             if (result == olm_error())
             {
-                const char *errorMsgPtr = olm_outbound_group_session_last_error(sessionPtr);
-                LOGE(" ## sessionKeyJni(): failure - session key failure Msg=%s",errorMsgPtr);
+                LOGE(" ## sessionKeyJni(): failure - session key failure Msg=%s",(const char *)olm_outbound_group_session_last_error(sessionPtr));
             }
             else
             {
@@ -301,8 +298,7 @@ JNIEXPORT jstring OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(encryptMessageJni)(JNIEnv
                                                        encryptedMsgLength);
             if(encryptedLength == olm_error())
             {
-                const char *errorMsgPtr = olm_outbound_group_session_last_error(sessionPtr);
-                LOGE(" ## encryptMessageJni(): failure - olm_group_encrypt Msg=%s",errorMsgPtr);
+                LOGE(" ## encryptMessageJni(): failure - olm_group_encrypt Msg=%s",(const char *)olm_outbound_group_session_last_error(sessionPtr));
             }
             else
             {
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.h b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.h
index 22c32a7..4b59b93 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.h
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.h
@@ -29,7 +29,7 @@ extern "C" {
 
 // session creation/destruction
 JNIEXPORT void OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(releaseSessionJni)(JNIEnv *env, jobject thiz);
-JNIEXPORT jlong OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(initNewSessionJni)(JNIEnv *env, jobject thiz);
+JNIEXPORT jlong OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(createNewSessionJni)(JNIEnv *env, jobject thiz);
 
 JNIEXPORT jint OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(initOutboundGroupSessionJni)(JNIEnv *env, jobject thiz);
 JNIEXPORT jstring OLM_OUTBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIEnv *env, jobject thiz);
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.cpp b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.cpp
index 9f64d2e..cfa132c 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.cpp
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.cpp
@@ -161,8 +161,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(initOutboundSessionJni)(JNIEnv *env, jobject
                                                             (void*)randomBuffPtr,
                                                             randomSize);
                 if(sessionResult == olm_error()) {
-                    const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-                    LOGE("## initOutboundSessionJni(): failure - session creation  Msg=%s",errorMsgPtr);
+                    LOGE("## initOutboundSessionJni(): failure - session creation  Msg=%s",(const char *)olm_session_last_error(sessionPtr));
                 }
                 else
                 {
@@ -236,8 +235,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(initInboundSessionJni)(JNIEnv *env, jobject
 
             sessionResult = olm_create_inbound_session(sessionPtr, accountPtr, (void*)messagePtr , messageLength);
             if(sessionResult == olm_error()) {
-                const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-                LOGE("## initInboundSessionJni(): failure - init inbound session creation  Msg=%s",errorMsgPtr);
+                LOGE("## initInboundSessionJni(): failure - init inbound session creation  Msg=%s",(const char *)olm_session_last_error(sessionPtr));
             }
             else
             {
@@ -302,8 +300,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(initInboundSessionFromIdKeyJni)(JNIEnv *env,
 
         sessionResult = olm_create_inbound_session_from(sessionPtr, accountPtr, theirIdentityKeyPtr, theirIdentityKeyLength, (void*)messagePtr , messageLength);
         if(sessionResult == olm_error()) {
-            const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-            LOGE("## initInboundSessionFromIdKeyJni(): failure - init inbound session creation  Msg=%s",errorMsgPtr);
+            LOGE("## initInboundSessionFromIdKeyJni(): failure - init inbound session creation  Msg=%s",(const char *)olm_session_last_error(sessionPtr));
         }
         else
         {
@@ -355,8 +352,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(matchesInboundSessionJni)(JNIEnv *env, jobje
 
         size_t matchResult = olm_matches_inbound_session(sessionPtr, (void*)messagePtr , messageLength);
         if(matchResult == olm_error()) {
-            const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-            LOGE("## matchesInboundSessionJni(): failure - no match  Msg=%s",errorMsgPtr);
+            LOGE("## matchesInboundSessionJni(): failure - no match  Msg=%s",(const char *)olm_session_last_error(sessionPtr));
         }
         else
         {
@@ -416,8 +412,7 @@ JNIEXPORT jint JNICALL OLM_SESSION_FUNC_DEF(matchesInboundSessionFromIdKeyJni)(J
 
         size_t matchResult = olm_matches_inbound_session_from(sessionPtr, (void const *)theirIdentityKeyPtr, identityKeyLength, (void*)messagePtr , messageLength);
         if(matchResult == olm_error()) {
-            const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-            LOGE("## matchesInboundSessionFromIdKeyJni(): failure - no match  Msg=%s",errorMsgPtr);
+            LOGE("## matchesInboundSessionFromIdKeyJni(): failure - no match  Msg=%s",(const char *)olm_session_last_error(sessionPtr));
         }
         else
         {
@@ -529,8 +524,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(encryptMessageJni)(JNIEnv *env, jobject thiz
                                             encryptedMsgLength);
                 if(result == olm_error())
                 {
-                    const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-                    LOGE("## encryptMessageJni(): failure - Msg=%s",errorMsgPtr);
+                    LOGE("## encryptMessageJni(): failure - Msg=%s",(const char *)olm_session_last_error(sessionPtr));
                 }
                 else
                 {
@@ -542,11 +536,10 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(encryptMessageJni)(JNIEnv *env, jobject thiz
 
                     // update message: encryptedMsgPtr => encryptedJstring
                     jstring encryptedJstring = env->NewStringUTF((const char*)encryptedMsgPtr);
-                    size_t encryptedUtfMsgLength = (size_t)env->GetStringUTFLength(encryptedJstring);
                     env->SetObjectField(aEncryptedMsg, encryptedMsgFieldId, (jobject)encryptedJstring);
 
                     retCode = ERROR_CODE_OK;
-                    LOGD("## encryptMessageJni(): success - result=%lu Type=%lu utfLength=%lu encryptedMsg=%s", result, messageType, encryptedUtfMsgLength, (const char*)encryptedMsgPtr);
+                    LOGD("## encryptMessageJni(): success - result=%lu Type=%lu utfLength=%lu encryptedMsg=%s", result, messageType, (size_t)env->GetStringUTFLength(encryptedJstring), (const char*)encryptedMsgPtr);
                 }
             }
         }
@@ -642,8 +635,7 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject t
 
         if(maxPlainTextLength == olm_error())
         {
-            const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-            LOGE("## decryptMessageJni(): failure - olm_decrypt_max_plaintext_length Msg=%s",errorMsgPtr);
+            LOGE("## decryptMessageJni(): failure - olm_decrypt_max_plaintext_length Msg=%s",(const char *)olm_session_last_error(sessionPtr));
         }
         else
         {
@@ -662,8 +654,7 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject t
                                                  maxPlainTextLength);
             if(plaintextLength == olm_error())
             {
-                const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-                LOGE("## decryptMessageJni(): failure - olm_decrypt Msg=%s",errorMsgPtr);
+                LOGE("## decryptMessageJni(): failure - olm_decrypt Msg=%s",(const char *)olm_session_last_error(sessionPtr));
             }
             else
             {
@@ -728,8 +719,7 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(getSessionIdentifierJni)(JNIEnv *env, job
 
             if (result == olm_error())
             {
-                const char *errorMsgPtr = olm_session_last_error(sessionPtr);
-                LOGE("## getSessionIdentifierJni(): failure - get session identifier failure Msg=%s",errorMsgPtr);
+                LOGE("## getSessionIdentifierJni(): failure - get session identifier failure Msg=%s",(const char *)olm_session_last_error(sessionPtr));
             }
             else
             {
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_utility.cpp b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_utility.cpp
index 6248d34..e11f7eb 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_utility.cpp
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_utility.cpp
@@ -203,8 +203,7 @@ JNIEXPORT jstring OLM_UTILITY_FUNC_DEF(sha256Jni)(JNIEnv *env, jobject thiz, jst
                                        hashLength);
             if(result == olm_error())
             {
-                const char *errorMsgPtr = olm_utility_last_error(utilityPtr);
-                LOGE("## sha256Jni(): failure - hash creation Msg=%s",errorMsgPtr);
+                LOGE("## sha256Jni(): failure - hash creation Msg=%s",(const char *)olm_utility_last_error(utilityPtr));
             }
             else
             {