Encode/Encrypt a single double (#212)

* feature: encode/encrypt a single double

* use new encrypt method

Co-authored-by: Bogdan Cebere <bogdan.cebere@gmail.com>

tenseal/cpp/tensors/ckkstensor.cpp

@@ -28,8 +28,8 @@ CKKSTensor::CKKSTensor(const shared_ptr<TenSEALContext>& ctx,
 
     } else {
         for (auto it = tensor.cbegin(); it != tensor.cend(); it++)
-            enc_data.push_back(CKKSTensor::encrypt(ctx, this->_init_scale,
-                                                   vector<double>({*it})));
+            enc_data.push_back(
+                CKKSTensor::encrypt(ctx, this->_init_scale, *it));
     }
 
     _data = TensorStorage<Ciphertext>(enc_data, enc_shape);
@@ -82,6 +82,16 @@ Ciphertext CKKSTensor::encrypt(const shared_ptr<TenSEALContext>& ctx,
     return ciphertext;
 }
 
+Ciphertext CKKSTensor::encrypt(const shared_ptr<TenSEALContext>& ctx,
+                               const double scale, const double data) {
+    Ciphertext ciphertext(*ctx->seal_context());
+    Plaintext plaintext;
+    ctx->encode<CKKSEncoder>(data, plaintext, scale);
+    ctx->encrypt(plaintext, ciphertext);
+
+    return ciphertext;
+}
+
 PlainTensor<double> CKKSTensor::decrypt(const shared_ptr<SecretKey>& sk) const {
     Plaintext plaintext;
     auto sz = this->_data.flat_size();