fix: replaced md5 hashing algorithm by sha-256

Author: abhinav-from-contentstack

contentstack/src/main/java/com/contentstack/sdk/Asset.java

@@ -385,8 +385,8 @@ public void fetch(FetchResultCallback callback) {
                 urlQueries.put("environment", headers.get("environment"));
             }
             String mainStringForMD5 = urlEndpoint + new JSONObject().toString() + headers.toString();
-            String md5Value = new SDKUtil().getMD5FromString(mainStringForMD5.trim());
-            File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + md5Value);
+            String shaValue = new SDKUtil().getSHAFromString(mainStringForMD5.trim());
+            File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + shaValue);
 
             switch (cachePolicyForCall) {
                 case IGNORE_CACHE:

contentstack/src/main/java/com/contentstack/sdk/AssetLibrary.java

@@ -215,8 +215,8 @@ public void fetchAll(FetchAssetsCallback assetsCallback) {
                 urlQueries.put("environment", headers.get("environment"));
             }
             String mainStringForMD5 = URL + new JSONObject().toString() + headers.toString();
-            String md5Value = new SDKUtil().getMD5FromString(mainStringForMD5.trim());
-            File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + md5Value);
+            String shaValue = new SDKUtil().getSHAFromString(mainStringForMD5.trim());
+            File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + shaValue);
             switch (cachePolicyForCall) {
                 case IGNORE_CACHE:
                     fetchFromNetwork(URL, urlQueries, headers, cacheFile.getPath(), assetsCallback);

contentstack/src/main/java/com/contentstack/sdk/Entry.java

@@ -1087,9 +1087,9 @@ public void fetch(EntryResultCallBack callBack) {
                 }
 
                 String mainStringForMD5 = URL + new JSONObject().toString() + headerAll.toString();
-                String md5Value = new SDKUtil().getMD5FromString(mainStringForMD5.trim());
+                String shaValue = new SDKUtil().getSHAFromString(mainStringForMD5.trim());
 
-                File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + md5Value);
+                File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + shaValue);
 
 
                 switch (cachePolicyForCall) {

contentstack/src/main/java/com/contentstack/sdk/Query.java

@@ -1595,8 +1595,8 @@ protected void execQuery(SingleQueryResultCallback callBack, QueryResultsCallBac
                 mainJSON.put("query", urlQueries);
                 mainJSON.put("_method", SDKConstant.RequestMethod.GET.toString());
                 String mainStringForMD5 = URL + mainJSON.toString() + headers.toString();
-                String md5Value = new SDKUtil().getMD5FromString(mainStringForMD5.trim());
-                File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + md5Value);
+                String shaValue = new SDKUtil().getSHAFromString(mainStringForMD5.trim());
+                File cacheFile = new File(SDKConstant.cacheFolderName + File.separator + shaValue);
                 CachePolicy cachePolicy = CachePolicy.NETWORK_ONLY;//contentTypeInstance.stackInstance.globalCachePolicyForCall;
                 if (cachePolicyForCall != null) {
                     cachePolicy = cachePolicyForCall;

contentstack/src/main/java/com/contentstack/sdk/SDKUtil.java

@@ -134,15 +134,15 @@ public static JSONObject getJsonFromCacheFile(File file) {
      * To encrypt given value.
      *
      * @param value string
-     * @return MD5 value
+     * @return SHA-256 value
      */
-    public String getMD5FromString(String value) {
+    public String getSHAFromString(String value) {
         String output;
         output = value.toString().trim();
         if (value.length() > 0) {
             try {
                 // Create MD5 Hash
-                MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
+                MessageDigest digest = java.security.MessageDigest.getInstance("SHA-256");
                 digest.reset();
                 digest.update(output.getBytes());
                 byte messageDigest[] = digest.digest();