Fix the decrypt issue (crash on V5.1.1) when the message to decrypt contains emojis:AndroidSdk_v0.2.0

- add an internal specific JNI function (javaCStringToUtf8()) to perform the UTF-8 conversion
- the SDK is configured to enable/disable the use of javaCStringToUtf8()

14 files changed, 168 insertions, 27 deletions

diff --git a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmAccountTest.java b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmAccountTest.java
index dc47d51..2c2711d 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmAccountTest.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmAccountTest.java
@@ -38,7 +38,6 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
-import java.util.Iterator;
 
 import static android.support.test.InstrumentationRegistry.getInstrumentation;
 import static org.junit.Assert.assertFalse;
@@ -59,8 +58,12 @@ public class OlmAccountTest {
 
     @BeforeClass
     public static void setUpClass(){
+        // enable UTF-8 specific conversion for pre Marshmallow(23) android versions,
+        // due to issue described here: https://github.com/eclipsesource/J2V8/issues/142
+        boolean isSpecificUtf8ConversionEnabled = android.os.Build.VERSION.SDK_INT < 23;
+
         // load native lib
-        mOlmManager = new OlmManager();
+        mOlmManager = new OlmManager(isSpecificUtf8ConversionEnabled);
 
         String olmLibVersion = mOlmManager.getOlmLibVersion();
         assertNotNull(olmLibVersion);
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 8fc0694..6e12463 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
@@ -60,8 +60,13 @@ public class OlmGroupSessionTest {
 
     @BeforeClass
     public static void setUpClass(){
+
+        // enable UTF-8 specific conversion for pre Marshmallow(23) android versions,
+        // due to issue described here: https://github.com/eclipsesource/J2V8/issues/142
+        boolean isSpecificUtf8ConversionEnabled = android.os.Build.VERSION.SDK_INT < 23;
+
         // load native lib
-        mOlmManager = new OlmManager();
+        mOlmManager = new OlmManager(isSpecificUtf8ConversionEnabled);
 
         String version = mOlmManager.getOlmLibVersion();
         assertNotNull(version);
@@ -408,4 +413,31 @@ public class OlmGroupSessionTest {
         }
     }
 
+    /**
+     * Specific test for the following run time error:
+     * "JNI DETECTED ERROR IN APPLICATION: input is not valid Modified UTF-8: illegal start byte 0xf0 in call to NewStringUTF".<br>
+     * When the msg to decrypt contain emojis, depending on the android platform, the NewStringUTF() behaves differently and
+     * can even crash.
+     * This issue is described in details here: https://github.com/eclipsesource/J2V8/issues/142
+     */
+    @Test
+    public void test18TestBadCharacterCrashInDecrypt() {
+        OlmInboundGroupSession bobInboundGroupSession=null;
+
+        // values taken from a "real life" crash case
+        String sessionKeyRef = "AgAAAAycZE6AekIctJWYxd2AWLOY15YmxZODm/WkgbpWkyycp6ytSp/R+wo84jRrzBNWmv6ySLTZ9R0EDOk9VI2eZyQ6Efdwyo1mAvrWvTkZl9yALPdkOIVHywyG65f1SNiLrnsln3hgsT1vUrISGyKtsljoUgQpr3JDPEhD0ilAi63QBjhnGCW252b+7nF+43rb6O6lwm93LaVwe2341Gdp6EkhTUvetALezEqDOtKN00wVqAbq0RQAnUJIowxHbMswg+FyoR1K1oCjnVEoF23O9xlAn5g1XtuBZP3moJlR2lwsBA";
+        String msgToDecryptWithEmoji = "AwgNEpABpjs+tYF+0y8bWtzAgYAC3N55p5cPJEEiGPU1kxIHSY7f2aG5Fj4wmcsXUkhDv0UePj922kgf+Q4dFsPHKq2aVA93n8DJAQ/FRfcM98B9E6sKCZ/PsCF78uBvF12Aaq9D3pUHBopdd7llUfVq29d5y6ZwX5VDoqV2utsATkKjXYV9CbfZuvvBMQ30ZLjEtyUUBJDY9K4FxEFcULytA/IkVnATTG9ERuLF/yB6ukSFR+iUWRYAmtuOuU0k9BvaqezbGqNoK5Grlkes+dYX6/0yUObumcw9/iAI";
+
+        // bob creates INBOUND GROUP SESSION
+        try {
+            bobInboundGroupSession = new OlmInboundGroupSession(sessionKeyRef);
+        } catch (OlmException e) {
+            assertTrue("Exception in test18TestBadCharacterCrashInDecrypt, Exception code=" + e.getExceptionCode(), false);
+        }
+
+        String decryptedMessage = bobInboundGroupSession.decryptMessage(msgToDecryptWithEmoji);
+        assertNotNull(decryptedMessage);
+    }
+
 }
+
diff --git a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmSessionTest.java b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmSessionTest.java
index 2494c80..1aeb3fb 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmSessionTest.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmSessionTest.java
@@ -51,8 +51,12 @@ public class OlmSessionTest {
 
     @BeforeClass
     public static void setUpClass(){
+        // enable UTF-8 specific conversion for pre Marshmallow(23) android versions,
+        // due to issue described here: https://github.com/eclipsesource/J2V8/issues/142
+        boolean isSpecificUtf8ConversionEnabled = android.os.Build.VERSION.SDK_INT < 23;
+
         // load native lib
-        mOlmManager = new OlmManager();
+        mOlmManager = new OlmManager(isSpecificUtf8ConversionEnabled);
 
         String version = mOlmManager.getOlmLibVersion();
         assertNotNull(version);
diff --git a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmUtilityTest.java b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmUtilityTest.java
index 9e03453..3006344 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmUtilityTest.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmUtilityTest.java
@@ -41,8 +41,12 @@ public class OlmUtilityTest {
 
     @BeforeClass
     public static void setUpClass(){
+        // enable UTF-8 specific conversion for pre Marshmallow(23) android versions,
+        // due to issue described here: https://github.com/eclipsesource/J2V8/issues/142
+        boolean isSpecificUtf8ConversionEnabled = android.os.Build.VERSION.SDK_INT < 23;
+
         // load native lib
-        mOlmManager = new OlmManager();
+        mOlmManager = new OlmManager(isSpecificUtf8ConversionEnabled);
 
         String version = mOlmManager.getOlmLibVersion();
         assertNotNull(version);
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 50e77f7..fa4ca1d 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
@@ -123,16 +123,26 @@ public class OlmInboundGroupSession extends CommonSerializeUtils implements Seri
     private native int initInboundGroupSessionWithSessionKeyJni(String aSessionKey);
 
 
+    /**
+     * Retrieve the base64-encoded identifier for this inbound group session.
+     * @return the session ID if operation succeed, null otherwise
+     */
     public String sessionIdentifier() {
         return sessionIdentifierJni();
     }
     private native String sessionIdentifierJni();
 
 
+    /**
+     * Decrypt the message passed in parameter.
+     * @param aEncryptedMsg the message to be decrypted
+     * @return the decrypted message if operation succeed, null otherwise.
+     */
     public String decryptMessage(String aEncryptedMsg) {
-        return decryptMessageJni(aEncryptedMsg);
+        String decryptedMessage = decryptMessageJni(aEncryptedMsg, OlmManager.ENABLE_STRING_UTF8_SPECIFIC_CONVERSION);
+        return decryptedMessage;
     }
-    private native String decryptMessageJni(String aEncryptedMsg);
+    private native String decryptMessageJni(String aEncryptedMsg, boolean aIsUtf8ConversionRequired);
 
 
     /**
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmManager.java b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmManager.java
index 92fbe2b..5170ee9 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmManager.java
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmManager.java
@@ -25,6 +25,18 @@ import android.util.Log;
 public class OlmManager {
     private static final String LOG_TAG = "OlmManager";
     private static final String SDK_OLM_VERSION = "V0.1.0_1";
+    /** specific flag to enable UTF-8 specific conversion for pre Marshmallow(23) android versions.<br>
+     * <a href="https://github.com/eclipsesource/J2V8/issues/142">NDK NewStringUTF() UTF8 issue</a>
+     **/
+    public static boolean ENABLE_STRING_UTF8_SPECIFIC_CONVERSION;
+
+    /**
+     * Constructor.
+     * @param aIsUtf8SpecificConversionEnabled true to enable JNI specific UTF-8 conversion, false otherwie
+     */
+    public OlmManager(boolean aIsUtf8SpecificConversionEnabled) {
+        ENABLE_STRING_UTF8_SPECIFIC_CONVERSION = aIsUtf8SpecificConversionEnabled;
+    }
 
     static {
         try {
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 6d570d1..dddc588 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
@@ -361,10 +361,10 @@ public class OlmSession extends CommonSerializeUtils implements Serializable {
      * @return the decrypted message if operation succeed, null otherwise
      */
     public String decryptMessage(OlmMessage aEncryptedMsg) {
-        return decryptMessageJni(aEncryptedMsg);
+        return decryptMessageJni(aEncryptedMsg, OlmManager.ENABLE_STRING_UTF8_SPECIFIC_CONVERSION);
     }
 
-    private native String decryptMessageJni(OlmMessage aEncryptedMsg);
+    private native String decryptMessageJni(OlmMessage aEncryptedMsg, boolean aIsUtf8ConversionRequired);
 
     /**
      * Return the number of unreleased OlmSession instances.<br>
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/Application.mk b/java/android/OlmLibSdk/olm-sdk/src/main/jni/Application.mk
index adff86a..6516f5e 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/Application.mk
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/Application.mk
@@ -1,3 +1,3 @@
 APP_PLATFORM := android-16
-APP_ABI := arm64-v8a armeabi-v7a x86 x86_64 armeabi
+APP_ABI := arm64-v8a armeabi-v7a armeabi x86_64  x86
 APP_STL := gnustl_static
\ No newline at end of file
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 05df22b..a78c2cf 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
@@ -180,7 +180,7 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIEn
 }
 
 
-JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg)
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg, jboolean aIsUtf8ConversionRequired)
 {
     jstring decryptedMsgRetValue = 0;
     OlmInboundGroupSession *sessionPtr = NULL;
@@ -245,11 +245,27 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
                 }
                 else
                 {
-                    // update decrypted buffer size
-                    plainTextMsgPtr[plaintextLength] = static_cast<char>('\0');
-
-                    LOGD(" ## decryptMessageJni(): decrypted returnedLg=%lu plainTextMsgPtr=%s",static_cast<long unsigned int>(plaintextLength), (char*)plainTextMsgPtr);
-                    decryptedMsgRetValue = env->NewStringUTF((const char*)plainTextMsgPtr);
+                    // UTF-8 conversion workaround for issue on Android versions older than Marshmallow (23)
+                    if(aIsUtf8ConversionRequired)
+                    {
+                        decryptedMsgRetValue = javaCStringToUtf8(env, plainTextMsgPtr, plaintextLength);
+                        if(0 == decryptedMsgRetValue)
+                        {
+                            LOGE(" ## decryptMessageJni(): UTF-8 Conversion failure - javaCStringToUtf8() returns null");
+                        }
+                        else
+                        {
+                            LOGD(" ## decryptMessageJni(): UTF-8 Conversion - decrypted returnedLg=%lu OK",static_cast<long unsigned int>(plaintextLength));
+                        }
+                    }
+                    else
+                    {
+                        // update decrypted buffer size
+                        plainTextMsgPtr[plaintextLength] = static_cast<char>('\0');
+
+                        LOGD(" ## decryptMessageJni(): decrypted returnedLg=%lu plainTextMsgPtr=%s",static_cast<long unsigned int>(plaintextLength), (char*)plainTextMsgPtr);
+                        decryptedMsgRetValue = env->NewStringUTF((const char*)plainTextMsgPtr);
+                    }
                 }
             }
         }
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 897ef46..ec402fd 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
@@ -33,7 +33,7 @@ JNIEXPORT jlong OLM_INBOUND_GROUP_SESSION_FUNC_DEF(createNewSessionJni)(JNIEnv *
 
 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);
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg, jboolean aIsUtf8ConversionRequired);
 
 // serialization
 JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(serializeDataWithKeyJni)(JNIEnv *env, jobject thiz, jstring aKey, jobject aErrorMsg);
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 29f0310..a5cae46 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
@@ -86,6 +86,7 @@ jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 jlong getUtilityInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
+jstring javaCStringToUtf8(JNIEnv *env, uint8_t *aCStringMsgPtr, size_t aMsgLength);
 
 #ifdef __cplusplus
 }
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 239fc68..561010d 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
@@ -270,4 +270,47 @@ jstring serializeDataWithKey(JNIEnv *env, jobject thiz,
     }
 
     return pickledDataRetValue;
-}
\ No newline at end of file
+}
+
+
+/**
+* Convert a C string into a UTF-8 format string.
+* The conversion is performed in JAVA side to workaround the issue in  NewStringUTF().
+* The problem is described here: https://github.com/eclipsesource/J2V8/issues/142
+*/
+jstring javaCStringToUtf8(JNIEnv *env, uint8_t *aCStringMsgPtr, size_t aMsgLength)
+{
+    jstring convertedRetValue = 0;
+    jbyteArray tempByteArray = NULL;
+
+    if((NULL == aCStringMsgPtr) || (NULL == env))
+    {
+        LOGE("## javaCStringToUtf8(): failure - invalid parameters (null)");
+    }
+    else if(NULL == (tempByteArray=env->NewByteArray(aMsgLength)))
+    {
+        LOGE("## javaCStringToUtf8(): failure - return byte array OOM");
+    }
+    else
+    {
+        env->SetByteArrayRegion(tempByteArray, 0, aMsgLength, (const jbyte*)aCStringMsgPtr);
+
+        // UTF-8 conversion from JAVA
+        jstring strEncode = (env)->NewStringUTF("UTF-8");
+        jclass jClass = env->FindClass("java/lang/String");
+        jmethodID cstor = env->GetMethodID(jClass, "<init>", "([BLjava/lang/String;)V");
+
+        if((0!=jClass) && (0!=jClass) && (0!=strEncode))
+        {
+            convertedRetValue = (jstring) env->NewObject(jClass, cstor, tempByteArray, strEncode);
+            LOGD(" ## javaCStringToUtf8(): succeed");
+            env->DeleteLocalRef(tempByteArray);
+        }
+        else
+        {
+            LOGE(" ## javaCStringToUtf8(): failure - invalid Java references");
+        }
+    }
+
+    return convertedRetValue;
+}
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 a31d48f..011ad44 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
@@ -574,7 +574,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(encryptMessageJni)(JNIEnv *env, jobject thiz
  * @param aEncryptedMsg message to decrypt
  * @return decrypted message if operation succeed, null otherwise
  */
-JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jobject aEncryptedMsg)
+JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jobject aEncryptedMsg, jboolean aIsUtf8ConversionRequired)
 {
     jstring decryptedMsgRetValue = 0;
     jclass encryptedMsgJClass = 0;
@@ -585,10 +585,10 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject t
     // ptrs
     OlmSession *sessionPtr = NULL;
     const char *encryptedMsgPtr = NULL; // <= obtained from encryptedMsgJstring
-    void *plainTextMsgPtr = NULL;
+    uint8_t *plainTextMsgPtr = NULL;
     char *tempEncryptedPtr = NULL;
 
-    LOGD("## decryptMessageJni(): IN ");
+    LOGD("## decryptMessageJni(): IN - OlmSession");
 
     if(NULL == (sessionPtr = (OlmSession*)getSessionInstanceId(env,thiz)))
     {
@@ -646,7 +646,7 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject t
             LOGD("## decryptMessageJni(): maxPlaintextLength=%lu",static_cast<long unsigned int>(maxPlainTextLength));
 
             // allocate output decrypted message
-            plainTextMsgPtr = static_cast<void*>(malloc((maxPlainTextLength+1)*sizeof(uint8_t)));
+            plainTextMsgPtr = static_cast<uint8_t*>(malloc((maxPlainTextLength+1)*sizeof(uint8_t)));
 
             // decrypt, but before reload encrypted buffer (previous one was destroyed)
             memcpy(tempEncryptedPtr, encryptedMsgPtr, encryptedMsgLength);
@@ -662,11 +662,27 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject t
             }
             else
             {
-                // update decrypted buffer size
-                (static_cast<char*>(plainTextMsgPtr))[plaintextLength] = static_cast<char>('\0');
+                // UTF-8 conversion workaround for issue on Android versions older than Marshmallow (23)
+                if(aIsUtf8ConversionRequired)
+                {
+                    decryptedMsgRetValue = javaCStringToUtf8(env, plainTextMsgPtr, plaintextLength);
+                    if(0 == decryptedMsgRetValue)
+                    {
+                        LOGE(" ## decryptMessageJni(): UTF-8 Conversion failure - javaCStringToUtf8() returns null");
+                    }
+                    else
+                    {
+                        LOGD(" ## decryptMessageJni(): UTF-8 Conversion - decrypted returnedLg=%lu OK",static_cast<long unsigned int>(plaintextLength));
+                    }
+                }
+                else
+                {
+                    // update decrypted buffer size
+                    plainTextMsgPtr[plaintextLength] = static_cast<char>('\0');
 
-                LOGD("## decryptMessageJni(): decrypted returnedLg=%lu plainTextMsgPtr=%s",static_cast<long unsigned int>(plaintextLength), static_cast<char*>(plainTextMsgPtr));
-                decryptedMsgRetValue = env->NewStringUTF(static_cast<const char*>(plainTextMsgPtr));
+                    LOGD("## decryptMessageJni(): decrypted returnedLg=%lu plainTextMsgPtr=%s",static_cast<long unsigned int>(plaintextLength), (char*)(plainTextMsgPtr));
+                    decryptedMsgRetValue = env->NewStringUTF((const char*)(plainTextMsgPtr));
+                }
             }
         }
     }
diff --git a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.h b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.h
index a08b775..e5bea92 100644
--- a/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.h
+++ b/java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.h
@@ -44,7 +44,7 @@ JNIEXPORT jint OLM_SESSION_FUNC_DEF(matchesInboundSessionFromIdKeyJni)(JNIEnv *e
 
 // encrypt/decrypt
 JNIEXPORT jint OLM_SESSION_FUNC_DEF(encryptMessageJni)(JNIEnv *env, jobject thiz, jstring aClearMsg, jobject aEncryptedMsg);
-JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jobject aEncryptedMsg);
+JNIEXPORT jstring OLM_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jobject aEncryptedMsg, jboolean aIsUtf8ConversionRequired);
 
 JNIEXPORT jstring OLM_SESSION_FUNC_DEF(getSessionIdentifierJni)(JNIEnv *env, jobject thiz);