hash single tag from data

example/integration_test/plugin_integration_test.dart

@@ -180,4 +180,16 @@ void main() {
       );
     });
   });
+
+  test('hash tag from x and y', () async {
+    const x =
+        '805f27cb4b6b8958587772011606a1fe264eb5cab0140dfc79d53f041d179647';
+    const y =
+        '52e22e74a5b57de0bb661a8116b06de8c3e70dc15a3865dea9a56a0288771c0d';
+
+    expect(
+      LibSpark.hashTag(x, y),
+      '875a3d3fe398ba1084ef68679baa81980ba3448c145afad725a9588c2f7fcfcf',
+    );
+  });
 }

lib/flutter_libsparkmobile.dart

@@ -746,6 +746,20 @@ abstract final class LibSpark {
     return hashes;
   }
 
+  static String hashTag(String x, String y) {
+    final xPtr = x.toNativeUtf8().cast<Char>();
+    final yPtr = y.toNativeUtf8().cast<Char>();
+
+    final result = _bindings.hashTag(xPtr, yPtr);
+    final hash = result.cast<Utf8>().toDartString();
+
+    malloc.free(xPtr);
+    malloc.free(yPtr);
+    malloc.free(result);
+
+    return hash;
+  }
+
   static int estimateSparkFee({
     required String privateKeyHex,
     int index = 1,

lib/src/flutter_libsparkmobile_bindings_generated.dart

@@ -295,6 +295,24 @@ class FlutterLibsparkmobileBindings {
   late final _hashTags = _hashTagsPtr.asFunction<
       ffi.Pointer<ffi.Char> Function(ffi.Pointer<ffi.UnsignedChar>, int)>();
 
+  ffi.Pointer<ffi.Char> hashTag(
+    ffi.Pointer<ffi.Char> x,
+    ffi.Pointer<ffi.Char> y,
+  ) {
+    return _hashTag(
+      x,
+      y,
+    );
+  }
+
+  late final _hashTagPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Pointer<ffi.Char> Function(
+              ffi.Pointer<ffi.Char>, ffi.Pointer<ffi.Char>)>>('hashTag');
+  late final _hashTag = _hashTagPtr.asFunction<
+      ffi.Pointer<ffi.Char> Function(
+          ffi.Pointer<ffi.Char>, ffi.Pointer<ffi.Char>)>();
+
   ffi.Pointer<SparkFeeResult> estimateSparkFee(
     ffi.Pointer<ffi.UnsignedChar> keyData,
     int index,

src/flutter_libsparkmobile.cpp

@@ -529,7 +529,6 @@ ValidateAddressResult* isValidSparkAddress(
     }
 }
 
-
 FFI_PLUGIN_EXPORT
 const char* hashTags(unsigned char* tags, int tagCount) {
     char* result = (char*) malloc(sizeof(char) * 64 * tagCount);
@@ -543,6 +542,16 @@ const char* hashTags(unsigned char* tags, int tagCount) {
     return result;
 }
 
+FFI_PLUGIN_EXPORT
+const char* hashTag(const char* x, const char* y) {
+    secp_primitives::GroupElement tag = secp_primitives::GroupElement(x, y, 16);
+    uint256 hash = primitives::GetLTagHash(tag);
+    std::string hex = hash.GetHex();
+    char* result = (char*) malloc(sizeof(char) * hex.length());
+    strcpy(result, hex.c_str());
+    return result;
+}
+
 FFI_PLUGIN_EXPORT
 SparkFeeResult* estimateSparkFee(
         unsigned char* keyData,

src/flutter_libsparkmobile.h

@@ -103,6 +103,9 @@ struct ValidateAddressResult* isValidSparkAddress(
 FFI_PLUGIN_EXPORT
 const char* hashTags(unsigned char* tags, int tagCount);
 
+FFI_PLUGIN_EXPORT
+const char* hashTag(const char* x, const char* y);
+
 FFI_PLUGIN_EXPORT
 struct SparkFeeResult* estimateSparkFee(
         unsigned char* keyData,