// ASP.NET Core 示例
[HttpGet("encrypted")]
public async Task<IActionResult> GetEncryptedData()
{
    // 1. 准备原始数据流
    var originalData = "这是要加密的敏感数据";
    var originalBytes = Encoding.UTF8.GetBytes(originalData);
    
    // 2. 创建AES加密器
    using var aes = Aes.Create();
    aes.Key = Convert.FromBase64String("你的256位密钥(base64编码)"); // 实际应用中应从安全存储获取
    aes.IV = new byte[16]; // 初始化向量
    
    // 3. 创建加密流
    using var memoryStream = new MemoryStream();
    using var cryptoStream = new CryptoStream(memoryStream, aes.CreateEncryptor(), CryptoStreamMode.Write);
    
    // 4. 写入数据并加密
    await cryptoStream.WriteAsync(originalBytes, 0, originalBytes.Length);
    await cryptoStream.FlushFinalBlockAsync();
    
    // 5. 返回加密后的流
    memoryStream.Position = 0;
    return File(memoryStream, "application/octet-stream", "encrypted.data");
}

[HttpGet("rsa-encrypted")]
public async Task<IActionResult> GetRsaEncryptedData()
{
    var originalData = "这是要加密的敏感数据";
    var originalBytes = Encoding.UTF8.GetBytes(originalData);
    
    using var rsa = RSA.Create();
    rsa.ImportFromPem("你的公钥PEM格式"); // 实际应用中应从安全存储获取
    
    var encryptedBytes = rsa.Encrypt(originalBytes, RSAEncryptionPadding.OaepSHA256);
    
    return File(new MemoryStream(encryptedBytes), "application/octet-stream", "rsa-encrypted.data");
}