c# How to encrypt file using x509 certificate

public static void EncryptFile(string encrDumpFilePath, string dumpFilePath, RSACryptoServiceProvider rsaKey)
        {
            using (AesManaged aesManaged = new AesManaged())
            {
                aesManaged.KeySize = 256;
                aesManaged.BlockSize = 128;
                aesManaged.Mode = CipherMode.CBC;
                using (ICryptoTransform transform = aesManaged.CreateEncryptor())
                {
                    RSAPKCS1KeyExchangeFormatter keyFormatter = new RSAPKCS1KeyExchangeFormatter(rsaKey);
                    byte[] keyEncrypted = keyFormatter.CreateKeyExchange(aesManaged.Key, aesManaged.GetType());
                    byte[] LenK = new byte[4];
                    byte[] LenIV = new byte[4];
                    int lKey = keyEncrypted.Length;
                    LenK = BitConverter.GetBytes(lKey);
                    int lIV = aesManaged.IV.Length;
                    LenIV = BitConverter.GetBytes(lIV);
                    int startFileName = dumpFilePath.LastIndexOf("\\") + 1;

                    string outFile = encrDumpFilePath;
                    Directory.CreateDirectory(Path.GetDirectoryName(encrDumpFilePath));
                    using (FileStream outFs = new FileStream(outFile, FileMode.Create))
                    {
                        outFs.Write(LenK, 0, 4);
                        outFs.Write(LenIV, 0, 4);
                        outFs.Write(keyEncrypted, 0, lKey);
                        outFs.Write(aesManaged.IV, 0, lIV);
                        using (CryptoStream outStreamEncrypted = new CryptoStream(outFs, transform, CryptoStreamMode.Write))
                        {
                            int count = 0;
                            int offset = 0;
                            int blockSizeBytes = aesManaged.BlockSize / 8;
                            byte[] data = new byte[blockSizeBytes];
                            int bytesRead = 0;

                            using (FileStream inFs = new FileStream(dumpFilePath, FileMode.Open))
                            {
                                do
                                {
                                    count = inFs.Read(data, 0, blockSizeBytes);
                                    offset += count;
                                    outStreamEncrypted.Write(data, 0, count);
                                    bytesRead += blockSizeBytes;
                                }
                                while (count > 0);
                                inFs.Close();
                            }
                            outStreamEncrypted.FlushFinalBlock();
                            outStreamEncrypted.Close();
                        }
                        outFs.Close();
                    }
                }
            }
        }