encrypt string with secret in csharp

main.cs
using System;
using System.Security.Cryptography;
using System.Text;

class Program
{
    static byte[] EncryptStringToBytes(string plainText, byte[] key, byte[] iv)
    {
        byte[] encrypted;

        using (Aes aesAlg = Aes.Create())
        {
            aesAlg.Key = key;
            aesAlg.IV = iv;

            ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            using (var msEncrypt = new System.IO.MemoryStream())
            using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
            using (var swEncrypt = new System.IO.StreamWriter(csEncrypt))
            {
                swEncrypt.Write(plainText);
                csEncrypt.FlushFinalBlock();
                encrypted = msEncrypt.ToArray();
            }
        }

        return encrypted;
    }

    static void Main(string[] args)
    {
        string plaintext = "Secret message to encrypt";
        byte[] key = Encoding.UTF8.GetBytes("mySecretKey12345");
        byte[] iv = Encoding.UTF8.GetBytes("mySecretIV1234567");

        byte[] encryptedBytes = EncryptStringToBytes(plaintext, key, iv);

        string encryptedString = Convert.ToBase64String(encryptedBytes);

        Console.WriteLine("Encrypted string: " + encryptedString);
    }
}
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