- Add new API for OlmUtility

- Introducing namespace AndroidOlmSdk
- Fix logs (function names mixed up)
- Add new check based on the calling java object instance type (IsInstanceOf())
- Fix return value for getXXXInstanceId() in case of failure. Now 0 is returned.

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_account.cpp

@@ -16,6 +16,8 @@
 
 #include "olm_account.h"
 
+using namespace AndroidOlmSdk;
+
 /**
 * Init memory allocation for account creation.
 * @return valid memory allocation, NULL otherwise
@@ -264,36 +266,36 @@ JNIEXPORT jbyteArray OLM_ACCOUNT_FUNC_DEF(oneTimeKeysJni)(JNIEnv *env, jobject t
     size_t keysResult;
     jbyteArray byteArrayRetValue = NULL;
 
-    LOGD("## oneTimeKeys(): accountPtr =%p",accountPtr);
+    LOGD("## oneTimeKeysJni(): IN");
 
     if(NULL == (accountPtr = (OlmAccount*)getAccountInstanceId(env,thiz)))
     {
-        LOGE("## oneTimeKeys(): failure - invalid Account ptr");
+        LOGE("## oneTimeKeysJni(): failure - invalid Account ptr");
     }
     else
     {   // keys memory allocation
         keysLength = olm_account_one_time_keys_length(accountPtr);
         if(NULL == (keysBytesPtr=(uint8_t *)malloc(keysLength*sizeof(uint8_t))))
         {
-            LOGE("## oneTimeKeys(): failure - one time keys array OOM");
+            LOGE("## oneTimeKeysJni(): failure - one time keys array OOM");
         }
         else
         {   // 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("## oneTimeKeys(): failure - error getting one time keys Msg=%s",errorMsgPtr);
+                LOGE("## oneTimeKeysJni(): failure - error getting one time keys Msg=%s",errorMsgPtr);
             }
             else
             {   // allocate the byte array to be returned to java
                 if(NULL == (byteArrayRetValue=env->NewByteArray(keysLength)))
                 {
-                    LOGE("## oneTimeKeys(): failure - return byte array OOM");
+                    LOGE("## oneTimeKeysJni(): failure - return byte array OOM");
                 }
                 else
                 {
                     env->SetByteArrayRegion(byteArrayRetValue, 0/*offset*/, keysLength, (const jbyte*)keysBytesPtr);
-                    LOGD("## oneTimeKeys(): success");
+                    LOGD("## oneTimeKeysJni(): success");
                 }
             }
 

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.cpp

@@ -16,6 +16,7 @@
 
 #include "olm_inbound_group_session.h"
 
+using namespace AndroidOlmSdk;
 
 /**
  * Release the session allocation made by initializeInboundGroupSessionMemory().<br>

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni.h

@@ -44,6 +44,8 @@
 
 #define FUNC_DEF(class_name,func_name) JNICALL Java_org_matrix_olm_##class_name##_##func_name
 
+namespace AndroidOlmSdk
+{
     // Error codes definition
     static const int ERROR_CODE_OK = 0;
     static const int ERROR_CODE_NO_MATCHING_ONE_TIME_KEYS = ERROR_CODE_OK+1;
@@ -51,14 +53,7 @@ static const int ERROR_CODE_KO = -1;
 
     // constants
     static const int ACCOUNT_CREATION_RANDOM_MODULO = 256;
-
+}
-
-// strings
-static const char *CLASS_OLM_OUTBOUND_GROUP_SESSION = "org/matrix/olm/OlmOutboundGroupSession";
-static const char *CLASS_OLM_INBOUND_GROUP_SESSION = "org/matrix/olm/OlmInboundGroupSession";
-static const char *CLASS_OLM_SESSION = "org/matrix/olm/OlmSession";
-static const char *CLASS_OLM_ACCOUNT = "org/matrix/olm/OlmAccount";
-static const char *CLASS_OLM_UTILITY = "org/matrix/olm/OlmUtility";
 
 #ifdef __cplusplus
 extern "C" {
@@ -70,7 +65,7 @@ jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
-
+jlong getUtilityInstanceId(JNIEnv* aJniEnv, jobject aJavaObject);
 
 #ifdef __cplusplus
 }

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni_helper.cpp

@@ -17,7 +17,9 @@
  * limitations under the License.
  */
 
-#include "olm_jni.h"
+#include "olm_jni_helper.h"
+
+using namespace AndroidOlmSdk;
 
 /**
 * Init a buffer with a given number of random values.
@@ -30,15 +32,15 @@ bool setRandomInBuffer(uint8_t **aBuffer2Ptr, size_t aRandomSize)
     bool retCode = false;
     if(NULL == aBuffer2Ptr)
     {
-        LOGD("## setRandomInBuffer(): failure - aBuffer=NULL");
+        LOGE("## setRandomInBuffer(): failure - aBuffer=NULL");
     }
     else if(0 == aRandomSize)
     {
-        LOGD("## setRandomInBuffer(): failure - random size=0");
+        LOGE("## setRandomInBuffer(): failure - random size=0");
     }
     else if(NULL == (*aBuffer2Ptr = (uint8_t*)malloc(aRandomSize*sizeof(uint8_t))))
     {
-        LOGD("## setRandomInBuffer(): failure - alloc mem OOM");
+        LOGE("## setRandomInBuffer(): failure - alloc mem OOM");
     }
     else
     {
@@ -67,7 +69,7 @@ bool setRandomInBuffer(uint8_t **aBuffer2Ptr, size_t aRandomSize)
 **/
 jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId=-1;
+  jlong instanceId = 0;
   jfieldID instanceIdField;
   jclass loaderClass;
   jclass requiredClass = 0;
@@ -78,7 +80,7 @@ jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
     if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
     {
-        LOGD("## getAccountInstanceId() failure - invalid instance of");
+        LOGE("## getAccountInstanceId() failure - invalid instance of");
     }
     else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
     {
@@ -90,17 +92,17 @@ jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
       }
       else
       {
-        LOGD("## getAccountInstanceId() ERROR! GetFieldID=null");
+        LOGE("## getAccountInstanceId() ERROR! GetFieldID=null");
       }
     }
     else
     {
-      LOGD("## getAccountInstanceId() ERROR! GetObjectClass=null");
+      LOGE("## getAccountInstanceId() ERROR! GetObjectClass=null");
     }
   }
   else
   {
-    LOGD("## getAccountInstanceId() ERROR! aJniEnv=NULL");
+    LOGE("## getAccountInstanceId() ERROR! aJniEnv=NULL");
   }
   LOGD("## getAccountInstanceId() success - instanceId=%lld",instanceId);
   return instanceId;
@@ -114,7 +116,7 @@ jlong getAccountInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 **/
 jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId=-1;
+  jlong instanceId = 0;
   jfieldID instanceIdField;
   jclass loaderClass;
   jclass requiredClass = 0;
@@ -125,7 +127,7 @@ jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
     if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
     {
-        LOGD("## getSessionInstanceId() failure - invalid instance of");
+        LOGE("## getSessionInstanceId() failure - invalid instance of");
     }
     else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
     {
@@ -136,17 +138,17 @@ jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
       }
       else
       {
-        LOGD("## getSessionInstanceId() ERROR! GetFieldID=null");
+        LOGE("## getSessionInstanceId() ERROR! GetFieldID=null");
       }
     }
     else
     {
-      LOGD("## getSessionInstanceId() ERROR! GetObjectClass=null");
+      LOGE("## getSessionInstanceId() ERROR! GetObjectClass=null");
     }
   }
   else
   {
-    LOGD("## getSessionInstanceId() ERROR! aJniEnv=NULL");
+    LOGE("## getSessionInstanceId() ERROR! aJniEnv=NULL");
   }
 
   //LOGD("## getSessionInstanceId() success - instanceId=%lld",instanceId);
@@ -162,7 +164,7 @@ jlong getSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 **/
 jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId=-1;
+  jlong instanceId = 0;
   jfieldID instanceIdField;
   jclass loaderClass;
   jclass requiredClass = 0;
@@ -173,7 +175,7 @@ jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
     if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
     {
-      LOGD("## getInboundGroupSessionInstanceId() failure - invalid instance of");
+      LOGE("## getInboundGroupSessionInstanceId() failure - invalid instance of");
     }
     else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
     {
@@ -184,17 +186,17 @@ jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
       }
       else
       {
-        LOGD("## getInboundGroupSessionInstanceId() ERROR! GetFieldID=null");
+        LOGE("## getInboundGroupSessionInstanceId() ERROR! GetFieldID=null");
       }
     }
     else
     {
-      LOGD("## getInboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
+      LOGE("## getInboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
     }
   }
   else
   {
-    LOGD("## getInboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
+    LOGE("## getInboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
   }
 
   return instanceId;
@@ -209,7 +211,7 @@ jlong getInboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 **/
 jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId=-1;
+  jlong instanceId = 0;
   jfieldID instanceIdField;
   jclass loaderClass;
   jclass requiredClass = 0;
@@ -220,7 +222,7 @@ jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
     if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
     {
-        LOGD("## getOutboundGroupSessionInstanceId() failure - invalid instance of");
+        LOGE("## getOutboundGroupSessionInstanceId() failure - invalid instance of");
     }
     else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
     {
@@ -231,17 +233,17 @@ jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
       }
       else
       {
-        LOGD("## getOutboundGroupSessionInstanceId() ERROR! GetFieldID=null");
+        LOGE("## getOutboundGroupSessionInstanceId() ERROR! GetFieldID=null");
       }
     }
     else
     {
-      LOGD("## getOutboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
+      LOGE("## getOutboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
     }
   }
   else
   {
-    LOGD("## getOutboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
+    LOGE("## getOutboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
   }
 
   return instanceId;
@@ -249,7 +251,7 @@ jlong getOutboundGroupSessionInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
 jlong getUtilityInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 {
-  jlong instanceId=-1;
+  jlong instanceId = 0;
   jfieldID instanceIdField;
   jclass loaderClass;
   jclass requiredClass = 0;
@@ -260,28 +262,28 @@ jlong getUtilityInstanceId(JNIEnv* aJniEnv, jobject aJavaObject)
 
     if((0 != requiredClass) && (JNI_TRUE != aJniEnv->IsInstanceOf(aJavaObject, requiredClass)))
     {
-        LOGD("## getOutboundGroupSessionInstanceId() failure - invalid instance of");
+        LOGE("## getUtilityInstanceId() failure - invalid instance of");
     }
     else if(0 != (loaderClass=aJniEnv->GetObjectClass(aJavaObject)))
     {
-      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmOutboundGroupSessionId", "J")))
+      if(0 != (instanceIdField=aJniEnv->GetFieldID(loaderClass, "mNativeOlmUtilityId", "J")))
       {
         instanceId = aJniEnv->GetLongField(aJavaObject, instanceIdField);
         aJniEnv->DeleteLocalRef(loaderClass);
       }
       else
       {
-        LOGD("## getOutboundGroupSessionInstanceId() ERROR! GetFieldID=null");
+        LOGE("## getUtilityInstanceId() ERROR! GetFieldID=null");
       }
     }
     else
     {
-      LOGD("## getOutboundGroupSessionInstanceId() ERROR! GetObjectClass=null");
+      LOGE("## getUtilityInstanceId() ERROR! GetObjectClass=null");
     }
   }
   else
   {
-    LOGD("## getOutboundGroupSessionInstanceId() ERROR! aJniEnv=NULL");
+    LOGE("## getUtilityInstanceId() ERROR! aJniEnv=NULL");
   }
 
   return instanceId;

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_jni_helper.h

@@ -0,0 +1,30 @@
+/**
+ * Created by pedrocon on 06/10/2016.
+ */
+/*
+ * Copyright 2016 OpenMarket Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "olm_jni.h"
+
+// constant strings
+namespace AndroidOlmSdk
+{
+    static const char *CLASS_OLM_INBOUND_GROUP_SESSION = "org/matrix/olm/OlmInboundGroupSession";
+    static const char *CLASS_OLM_OUTBOUND_GROUP_SESSION = "org/matrix/olm/OlmOutboundGroupSession";
+    static const char *CLASS_OLM_SESSION = "org/matrix/olm/OlmSession";
+    static const char *CLASS_OLM_ACCOUNT = "org/matrix/olm/OlmAccount";
+    static const char *CLASS_OLM_UTILITY = "org/matrix/olm/OlmUtility";
+}

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_outbound_group_session.cpp

@@ -16,6 +16,7 @@
 
 #include "olm_outbound_group_session.h"
 
+using namespace AndroidOlmSdk;
 
 /**
  * Release the session allocation made by initializeOutboundGroupSessionMemory().<br>

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_session.cpp

@@ -16,6 +16,7 @@
 
 #include "olm_session.h"
 
+using namespace AndroidOlmSdk;
 
 /**
 * Init memory allocation for a session creation.<br>
@@ -698,20 +699,26 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(getSessionIdentifierJni)(JNIEnv *env, job
     void *sessionIdPtr = NULL;
     jstring returnValueStr=0;
 
-    // get the size to alloc to contain the id
+    LOGD("## getSessionIdentifierJni(): IN ");
-    size_t lengthSessionId = olm_session_id_length(sessionPtr);
 
     if(NULL == (sessionPtr = (OlmSession*)getSessionInstanceId(env,thiz)))
     {
         LOGE("## getSessionIdentifierJni(): failure - invalid Session ptr=NULL");
     }
-    else if(NULL == (sessionIdPtr = (void*)malloc((lengthSessionId+1)*sizeof(uint8_t))))
+    else
+    {
+        // get the size to alloc to contain the id
+        size_t lengthSessionId = olm_session_id_length(sessionPtr);
+        LOGD("## getSessionIdentifierJni(): lengthSessionId=%lu",lengthSessionId);
+
+        if(NULL == (sessionIdPtr = (void*)malloc((lengthSessionId+1)*sizeof(uint8_t))))
         {
            LOGE("## getSessionIdentifierJni(): failure - identifier allocation OOM");
         }
         else
         {
             size_t result = olm_session_id(sessionPtr, sessionIdPtr, lengthSessionId);
+
             if (result == olm_error())
             {
                 const char *errorMsgPtr = olm_session_last_error(sessionPtr);
@@ -727,6 +734,7 @@ JNIEXPORT jstring OLM_SESSION_FUNC_DEF(getSessionIdentifierJni)(JNIEnv *env, job
             }
             free(sessionIdPtr);
         }
+    }
 
     return returnValueStr;
 }

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_utility.cpp

@@ -14,24 +14,220 @@
  * limitations under the License.
  */
 
-#include "olm_jni.h"
 #include "olm_utility.h"
 
+using namespace AndroidOlmSdk;
+
+OlmUtility* initializeUtilityMemory()
+{
+    OlmUtility* utilityPtr = NULL;
+    size_t utilitySize = olm_utility_size();
+
+    if(NULL != (utilityPtr=(OlmUtility*)malloc(utilitySize)))
+    {
+      utilityPtr = olm_utility(utilityPtr);
+      LOGD("## initializeUtilityMemory(): success - OLM utility size=%lu",utilitySize);
+    }
+    else
+    {
+      LOGE("## initializeUtilityMemory(): failure - OOM");
+    }
+
+    return utilityPtr;
+}
+
+
+JNIEXPORT jlong OLM_UTILITY_FUNC_DEF(initUtilityJni)(JNIEnv *env, jobject thiz)
+{
+    OlmUtility* utilityPtr = NULL;
+
+    LOGD("## initUtilityJni(): IN");
+
+    // init account memory allocation
+    if(NULL == (utilityPtr = initializeUtilityMemory()))
+    {
+        LOGE(" ## initUtilityJni(): failure - init OOM");
+    }
+    else
+    {
+       LOGD(" ## initUtilityJni(): success");
+    }
+
+    return (jlong)(intptr_t)utilityPtr;
+}
+
+
+JNIEXPORT void OLM_UTILITY_FUNC_DEF(releaseUtilityJni)(JNIEnv *env, jobject thiz)
+{
+  OlmUtility* utilityPtr = NULL;
+
+  if(NULL == (utilityPtr = (OlmUtility*)getUtilityInstanceId(env,thiz)))
+  {
+      LOGE("## releaseUtilityJni(): failure - utility ptr=NULL");
+  }
+  else
+  {
+    olm_clear_utility(utilityPtr);
+    free(utilityPtr);
+  }
+}
+
+
 /**
  * Verify an ed25519 signature.
  * If the key was too small then the message will be "OLM.INVALID_BASE64".
  * If the signature was invalid then the message will be "OLM.BAD_MESSAGE_MAC".
- * @param aKey the ed25519 key.
+ *
- * @param aMessage the message which was signed.
+ * @param aSignature the base64-encoded message signature to be checked.
- * @param aSignature the base64-encoded signature to be checked.
+ * @param aKey the ed25519 key (fingerprint key)
+ * @param aMessage the message which was signed
  * @param the result error if there is a problem with the verification.
  * @return true if validation succeed, false otherwise
  */
-JNIEXPORT bool OLM_UTILITY_FUNC_DEF(ed25519VerifyJni)(JNIEnv *env, jobject thiz, jstring aKey, jstring aMessage, jstring aSignature, jobject aErrorMessage)
+JNIEXPORT jstring OLM_UTILITY_FUNC_DEF(verifyEd25519SignatureJni)(JNIEnv *env, jobject thiz, jstring aSignature, jstring aKey, jstring aMessage)
 {
-    bool retCode = false;
+    jstring errorMessageRetValue = 0;
+    OlmUtility* utilityPtr = NULL;
+    const char* signaturePtr = NULL;
+    const char* keyPtr = NULL;
+    const char* messagePtr = NULL;
 
+    LOGD("## verifyEd25519SignatureJni(): IN");
 
-
+    if(NULL == (utilityPtr = (OlmUtility*)getUtilityInstanceId(env,thiz)))
-    return retCode;
+    {
+        LOGE(" ## verifyEd25519SignatureJni(): failure - invalid utility ptr=NULL");
+    }
+    else if((0 == aSignature) || (0 == aKey) || (0 == aMessage))
+    {
+        LOGE(" ## verifyEd25519SignatureJni(): failure - invalid input parameters ");
+    }
+    else if(0 == (signaturePtr = env->GetStringUTFChars(aSignature, 0)))
+    {
+        LOGE(" ## verifyEd25519SignatureJni(): failure - signature JNI allocation OOM");
+    }
+    else if(0 == (keyPtr = env->GetStringUTFChars(aKey, 0)))
+    {
+        LOGE(" ## verifyEd25519SignatureJni(): failure - key JNI allocation OOM");
+    }
+    else if(0 == (messagePtr = env->GetStringUTFChars(aMessage, 0)))
+    {
+        LOGE(" ## verifyEd25519SignatureJni(): failure - message JNI allocation OOM");
+    }
+    else
+    {
+        size_t signatureLength = (size_t)env->GetStringUTFLength(aSignature);
+        size_t keyLength = (size_t)env->GetStringUTFLength(aKey);
+        size_t messageLength = (size_t)env->GetStringUTFLength(aMessage);
+        LOGD(" ## verifyEd25519SignatureJni(): signatureLength=%lu keyLength=%lu messageLength=%lu",signatureLength,keyLength,messageLength);
+
+        size_t result = olm_ed25519_verify(utilityPtr,
+                                           (void const *)keyPtr,
+                                           keyLength,
+                                           (void const *)messagePtr,
+                                           messageLength,
+                                           (void*)signaturePtr,
+                                           signatureLength);
+        if(result == olm_error()) {
+            const char *errorMsgPtr = olm_utility_last_error(utilityPtr);
+            errorMessageRetValue = env->NewStringUTF(errorMsgPtr);
+            LOGE("## verifyEd25519SignatureJni(): failure - session creation  Msg=%s",errorMsgPtr);
+        }
+        else
+        {
+            LOGD("## verifyEd25519SignatureJni(): success - result=%ld", result);
+        }
+    }
+
+    // free alloc
+    if(NULL != signaturePtr)
+    {
+     env->ReleaseStringUTFChars(aSignature, signaturePtr);
+    }
+
+    if(NULL != keyPtr)
+    {
+     env->ReleaseStringUTFChars(aKey, keyPtr);
+    }
+
+    if(NULL != messagePtr)
+    {
+     env->ReleaseStringUTFChars(aMessage, messagePtr);
+    }
+
+    return errorMessageRetValue;
+}
+
+/**
+* Compute the digest (SHA 256) for the message passed in parameter.<br>
+* The digest value is the function return value.
+* @param aMessage
+* @return digest of the message if operation succeed, null otherwise
+**/
+JNIEXPORT jstring OLM_UTILITY_FUNC_DEF(sha256Jni)(JNIEnv *env, jobject thiz, jstring aMessageToHash)
+{
+    jstring sha256RetValue = 0;
+    OlmUtility* utilityPtr = NULL;
+    const char* messagePtr = NULL;
+    void *hashValuePtr = NULL;
+
+    LOGD("## sha256Jni(): IN");
+
+    if(NULL == (utilityPtr = (OlmUtility*)getUtilityInstanceId(env,thiz)))
+    {
+        LOGE(" ## sha256Jni(): failure - invalid utility ptr=NULL");
+    }
+    else if(0 == aMessageToHash)
+    {
+        LOGE(" ## sha256Jni(): failure - invalid message parameters ");
+    }
+    else if(0 == (messagePtr = env->GetStringUTFChars(aMessageToHash, 0)))
+    {
+        LOGE(" ## sha256Jni(): failure - message JNI allocation OOM");
+    }
+    else
+    {
+        // get lengths
+        size_t messageLength = (size_t)env->GetStringUTFLength(aMessageToHash);
+        size_t hashLength = olm_sha256_length(utilityPtr);
+
+        if(NULL == (hashValuePtr = static_cast<void*>(malloc((hashLength+1)*sizeof(uint8_t)))))
+        {
+            LOGE("## sha256Jni(): failure - hash value allocation OOM");
+        }
+        else
+        {
+            size_t result = olm_sha256(utilityPtr,
+                                       (void const *)messagePtr,
+                                       messageLength,
+                                       (void *)hashValuePtr,
+                                       hashLength);
+            if(result == olm_error())
+            {
+                const char *errorMsgPtr = olm_utility_last_error(utilityPtr);
+                LOGE("## sha256Jni(): failure - hash creation Msg=%s",errorMsgPtr);
+            }
+            else
+            {
+                // update length
+                (static_cast<char*>(hashValuePtr))[result] = static_cast<char>('\0');
+
+                LOGD("## sha256Jni(): success - result=%lu hashValue=%s",result, (char*)hashValuePtr);
+                sha256RetValue = env->NewStringUTF((const char*)hashValuePtr);
+            }
+        }
+
+    }
+
+    if(NULL != hashValuePtr)
+    {
+        free(hashValuePtr);
+    }
+
+    if(NULL != messagePtr)
+    {
+        env->ReleaseStringUTFChars(aMessageToHash, messagePtr);
+    }
+
+    return sha256RetValue;
 }

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_utility.h

@@ -17,13 +17,20 @@
 #ifndef _OMLUTILITY_H
 #define _OMLUTILITY_H
 
+#include "olm_jni.h"
+#include "olm/olm.h"
+
 #define OLM_UTILITY_FUNC_DEF(func_name) FUNC_DEF(OlmUtility,func_name)
 
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-JNIEXPORT bool OLM_UTILITY_FUNC_DEF(ed25519VerifyJni)(JNIEnv *env, jobject thiz, jstring aKey, jstring aMessage, jstring aSignature, jobject aErrorMessage);
+JNIEXPORT jlong   OLM_UTILITY_FUNC_DEF(initUtilityJni)(JNIEnv *env, jobject thiz);
+JNIEXPORT void    OLM_UTILITY_FUNC_DEF(releaseUtilityJni)(JNIEnv *env, jobject thiz);
+JNIEXPORT jstring OLM_UTILITY_FUNC_DEF(verifyEd25519SignatureJni)(JNIEnv *env, jobject thiz, jstring aSignature, jstring aKey, jstring aMessage);
+JNIEXPORT jstring OLM_UTILITY_FUNC_DEF(sha256Jni)(JNIEnv *env, jobject thiz, jstring aMessageToHash);
 
 #ifdef __cplusplus
 }