mcdiscordbot/MinecraftDiscordBot/AesCipher.cs

using System.Security.Cryptography;

namespace MinecraftDiscordBot;

public class AesCipher : ICipher {
    private readonly byte[] key;
    private readonly byte[] iv;

    public AesCipher() {
        using var aes = Aes.Create();
        aes.GenerateKey();
        aes.GenerateIV();
        key = aes.Key;
        iv = aes.IV;
    }

    public byte[] Encrypt(byte[] plain) {
        using var aes = Aes.Create();
        aes.Key = key;
        aes.IV = iv;
        var transformer = aes.CreateEncryptor();
        using var ms = new MemoryStream();
        using (var cs = new CryptoStream(ms, transformer, CryptoStreamMode.Write))
            cs.Write(plain);
        return ms.ToArray();
    }

    public byte[] Decrypt(byte[] cipher) {
        using Aes aes = Aes.Create();
        aes.Key = key;
        aes.IV = iv;
        var transformer = aes.CreateDecryptor();
        using MemoryStream ms = new MemoryStream(cipher);
        using CryptoStream cs = new CryptoStream(ms, transformer, CryptoStreamMode.Read);
        using MemoryStream os = new MemoryStream();
        cs.CopyTo(os);
        return os.ToArray();
    }
}

public interface ICipher {
    byte[] Decrypt(byte[] cipher);
    byte[] Encrypt(byte[] plain);
}