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HMACSHA256 Hash key generated by C++/CLI is different from Java Generated Hash Key

C++/CLI Function

I am generating Hash key using C++/CLI and Sending Data and Hashkey Over the network to Other Application which is coded in Java.

But Java Application generates a different HashKey.

Is it due to different applications on different servers that the hashkeys are different ?

Any Idea where am i going wrong ?

Thanking in Advance.

char* EncodeData(char* ap_key, char* ap_sourceData)

char* lp_data_to_send = NULL;
int key_len = strlen(ap_key);

String^ lv_data = gcnew String(ap_sourceData);//Getting Data in System String
array<Byte>^ lv_main_data = Encoding::UTF8->GetBytes(lv_data);//Encoding to UTF-8

array<Byte>^key = gcnew array< Byte >(key_len + 2);
Marshal::Copy((IntPtr)ap_key, key, 0, key_len); //Copy key in System Array Byte

// Initialize the keyed hash object.
HMACSHA256^ myhmacsha256 = gcnew HMACSHA256(key);

// Compute the hash of the input file.
array<Byte>^hashValue = myhmacsha256->ComputeHash(lv_main_data);

String^ lv_hex_convert = BitConverter::ToString(hashValue)->Replace("-",""); //Converted to Hexadecimal and replacing '-' with ""
Console::WriteLine(lv_hex_convert);//Converted Hexadecimal Hashkey

//Converting to Char*
lp_data_to_send = (char*)(void*)System::Runtime::InteropServices::Marshal::StringToHGlobalAnsi(lv_hex_convert);//Converting again to char* to be send to Calling Function

myhmacsha256->Clear(); //myhmacsha256 clear Instance
return lp_data_to_send;//Return Char*



int main()

//Secret Key shared by C++/CLi application and Java Application
String ^ lv_key_g = " My Secret Key";
char lv_sourceData = "My data" ;
char lv_destinationData[512] = "" ;
char* lp_ret = NULL;

array<Byte>^secretkey = gcnew array<Byte>(65); //Declaring Array
//Converting to UTF-8
secretkey = Encoding::UTF8->GetBytes(lv_key_g);

/*Converting to char* */

pin_ptr<System::Byte> p = &secretkey[0];
unsigned char* pby = p;
//Converting to Char* to send
char* lp_key = reinterpret_cast<char*>(pby);//Converting data to char*

/*End converting to Byte Array*/

lp_ret = EncodeData(lp_key, lv_sourceData);//calling Function



JAVA-FUNCTION

String key = "My Key"; //Hash Key Shared by Both Application
String hashKey = "My Data"; //Data Shared by both Application
Mac sha256_HMAC = null;
try
//Creating Instance
sha256_HMAC = Mac.getInstance("HmacSHA256");
catch (NoSuchAlgorithmException e)
e.printStackTrace();

SecretKeySpec secret_key = null;
try

secret_key = new SecretKeySpec(key.getBytes("UTF-8"), "HmacSHA256");//UTF-8 Secret Key
catch (UnsupportedEncodingException e)
e.printStackTrace();

try
sha256_HMAC.init(secret_key); //Init Secret Key
catch (InvalidKeyException e)
e.printStackTrace();

final byte mac_data = sha256_HMAC.doFinal(hashKey.getBytes()); //Get Data in Bytes

String result = "";
for (final byte element : mac_data)
//Using Radix 16 to convert to String
result += Integer.toString((element & 0xff) + 0x100, 16).substring(1); //Converting to Hexadecimal

System.out.print(result);//Hashkey Print


1 Answer
1

return lp_data_to_send;//Return Char* will return a dangling pointer, you should probably return a reference-counted string lv_hex_convert instead. Another suspicious thing is that key is 2 bytes longer than required.

return lp_data_to_send;//Return Char*

lv_hex_convert

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