Proteção de dadosData protection

Este artigo explica como usar a classe DataProtectionProvider no namespace Windows.Security.Cryptography.DataProtection para criptografar e descriptografar dados digitais em um aplicativo UWP.This article explains how to use the DataProtectionProvider class in the Windows.Security.Cryptography.DataProtection namespace to encrypt and decrypt digital data in a UWP app.

Você pode usar as APIs de proteção de dados de várias formas:You can use the data protection APIs in multiple ways:

  • Para proteger dados de uma entidade de segurança do Active Directory (AD), como um grupo do AD.To protect data to an Active Directory (AD) security principal like an AD group. Qualquer membro do grupo pode descriptografar os dados.Any member of the group can decrypt the data.
  • Para proteger dados na chave pública contida em um certificado X.509.To protect data to the public key contained in an X.509 certificate. O proprietário da chave privada pode descriptografar os dados.The owner of the private key can decrypt the data.
  • Para proteger dados usando uma chave simétrica.To protect data by using a symmetric key. Isso funciona, por exemplo, para proteger dados em uma entidade não AD como o Live ID.This works, for example, to protect data to a non-AD principal such as Live ID.
  • Para proteger dados nas credenciais (senha) usadas durante o logon em um site.To protect data to the credentials (password) used during logon to a website.

Para proteger dados, ao criar um objeto DataProtectionProvider, você deve especificar um descritor de proteção antes de chamar ProtectAsync ou ProtectStreamAsync.To protect data, when you create a DataProtectionProvider object you must specify a protection descriptor before calling ProtectAsync or ProtectStreamAsync. O exemplo a seguir mostra possíveis descritores de proteção de amostra.The following example shows possible sample protection descriptors.

Protegendo dados estáticosProtecting static data

O exemplo seguinte mostra como usar os métodos ProtectAsync e UnprotectAsync para proteger dados estáticos assíncronos para o SID do usuário atual.The following example shows how to use the ProtectAsync and UnprotectAsync methods to asynchronously protect static data to the current user's SID.

using Windows.Security.Cryptography;
using Windows.Security.Cryptography.DataProtection;
using Windows.Storage.Streams;
using System.Threading.Tasks;

namespace SampleProtectAsync
{
    sealed partial class StaticDataProtectionApp : Application
    {
        public StaticDataProtectionApp()
        {
            // Initialize the application.
            this.InitializeComponent();

            // Protect data asynchronously.
            this.Protect();
        }

        public async void Protect()
        {
            // Initialize function arguments.
            String strMsg = "This is a message to be protected.";
            String strDescriptor = "LOCAL=user";
            BinaryStringEncoding encoding = BinaryStringEncoding.Utf8;

            // Protect a message to the local user.
            IBuffer buffProtected = await this.SampleProtectAsync(
                strMsg,
                strDescriptor,
                encoding);

            // Decrypt the previously protected message.
            String strDecrypted = await this.SampleUnprotectData(
                buffProtected,
                encoding);
        }

        public async Task<IBuffer> SampleProtectAsync(
            String strMsg,
            String strDescriptor,
            BinaryStringEncoding encoding)
        {
            // Create a DataProtectionProvider object for the specified descriptor.
            DataProtectionProvider Provider = new DataProtectionProvider(strDescriptor);

            // Encode the plaintext input message to a buffer.
            encoding = BinaryStringEncoding.Utf8;
            IBuffer buffMsg = CryptographicBuffer.ConvertStringToBinary(strMsg, encoding);

            // Encrypt the message.
            IBuffer buffProtected = await Provider.ProtectAsync(buffMsg);

            // Execution of the SampleProtectAsync function resumes here
            // after the awaited task (Provider.ProtectAsync) completes.
            return buffProtected;
        }

        public async Task<String> SampleUnprotectData(
            IBuffer buffProtected,
            BinaryStringEncoding encoding)
        {
            // Create a DataProtectionProvider object.
            DataProtectionProvider Provider = new DataProtectionProvider();

            // Decrypt the protected message specified on input.
            IBuffer buffUnprotected = await Provider.UnprotectAsync(buffProtected);

            // Execution of the SampleUnprotectData method resumes here
            // after the awaited task (Provider.UnprotectAsync) completes
            // Convert the unprotected message from an IBuffer object to a string.
            String strClearText = CryptographicBuffer.ConvertBinaryToString(encoding, buffUnprotected);

            // Return the plaintext string.
            return strClearText;
        }
    }
}

Protegendo dados de fluxoProtecting stream data

O exemplo a seguir mostra como usar os métodos ProtectStreamAsync e UnprotectStreamAsync para proteger de forma assíncrona os dados de fluxo para o SID do usuário atual.The following example shows how to use the ProtectStreamAsync and UnprotectStreamAsync methods to asynchronously protect stream data to the current user's SID.

using Windows.Security.Cryptography;
using Windows.Security.Cryptography.DataProtection;
using Windows.Storage.Streams;
using System.Threading.Tasks;

namespace SampleProtectStreamAsync
{

    sealed partial class StreamDataProtectionApp : Application
    {
        public StreamDataProtectionApp()
        {
            // Initialize the application.
            this.InitializeComponent();

            // Protect a stream synchronously
            this.ProtectData();
         }

        public async void ProtectData()
        {
            // Initialize function arguments.
            String strDescriptor = "LOCAL=user";
            String strLoremIpsum = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse elementum "
                + "ullamcorper eros, vitae gravida nunc consequat sollicitudin. Vivamus lacinia, "
                + "diam a molestie porttitor, sapien neque volutpat est, non suscipit leo dolor "
                + "sit amet nisl. Praesent tincidunt tincidunt quam ut pharetra. Sed tincidunt "
                + "sit amet nisl. Praesent tincidunt tincidunt quam ut pharetra. Sed tincidunt "
                + "porttitor massa, at convallis dolor dictum suscipit. Nullam vitae lectus in "
                + "lorem scelerisque convallis sed scelerisque orci. Praesent sed ligula vel erat "
                + "eleifend tempus. Nullam dignissim aliquet mauris a aliquet. Nulla augue justo, "
                + "posuere a consectetur ut, suscipit et sem. Proin eu libero ut felis tincidunt "
                + "interdum. Curabitur vulputate eros nec sapien elementum ut dapibus eros "
                + "dapibus. Suspendisse quis dui dolor, non imperdiet leo. In consequat, odio nec "
                + "aliquam tincidunt, magna enim ultrices massa, ac pharetra est urna at arcu. "
                + "Nunc suscipit, velit non interdum suscipit, lectus lectus auctor tortor, quis "
                + "ultrices orci felis in dolor. Etiam congue pretium libero eu vestibulum. "
                + "Mauris bibendum erat eleifend nibh consequat eu pharetra metus convallis. "
                + "Morbi sem eros, venenatis vel vestibulum consequat, hendrerit rhoncus purus.";
            BinaryStringEncoding encoding = BinaryStringEncoding.Utf16BE;

            // Encrypt the data as a stream.
            IBuffer buffProtected = await this.SampleDataProtectionStream(
                strDescriptor,
                strLoremIpsum,
                encoding);

            // Decrypt a data stream.
            String strUnprotected = await this.SampleDataUnprotectStream(
                buffProtected,
                encoding);
        }

        public async Task<IBuffer> SampleDataProtectionStream(
            String descriptor,
            String strMsg,
            BinaryStringEncoding encoding)
        {
            // Create a DataProtectionProvider object for the specified descriptor.
            DataProtectionProvider Provider = new DataProtectionProvider(descriptor);

            // Convert the input string to a buffer.
            IBuffer buffMsg = CryptographicBuffer.ConvertStringToBinary(strMsg, encoding);

            // Create a random access stream to contain the plaintext message.
            InMemoryRandomAccessStream inputData = new InMemoryRandomAccessStream();

            // Create a random access stream to contain the encrypted message.
            InMemoryRandomAccessStream protectedData = new InMemoryRandomAccessStream();

            // Retrieve an IOutputStream object and fill it with the input (plaintext) data.
            IOutputStream outputStream = inputData.GetOutputStreamAt(0);
            DataWriter writer = new DataWriter(outputStream);
            writer.WriteBuffer(buffMsg);
            await writer.StoreAsync();
            await outputStream.FlushAsync();

            // Retrieve an IInputStream object from which you can read the input data.
            IInputStream source = inputData.GetInputStreamAt(0);

            // Retrieve an IOutputStream object and fill it with encrypted data.
            IOutputStream dest = protectedData.GetOutputStreamAt(0);
            await Provider.ProtectStreamAsync(source, dest);
            await dest.FlushAsync();

            //Verify that the protected data does not match the original
            DataReader reader1 = new DataReader(inputData.GetInputStreamAt(0));
            DataReader reader2 = new DataReader(protectedData.GetInputStreamAt(0));
            await reader1.LoadAsync((uint)inputData.Size);
            await reader2.LoadAsync((uint)protectedData.Size);
            IBuffer buffOriginalData = reader1.ReadBuffer((uint)inputData.Size);
            IBuffer buffProtectedData = reader2.ReadBuffer((uint)protectedData.Size);

            if (CryptographicBuffer.Compare(buffOriginalData, buffProtectedData))
            {
                throw new Exception("ProtectStreamAsync returned unprotected data");
            }

            // Return the encrypted data.
            return buffProtectedData;
        }

        public async Task<String> SampleDataUnprotectStream(
            IBuffer buffProtected,
            BinaryStringEncoding encoding)
        {
            // Create a DataProtectionProvider object.
            DataProtectionProvider Provider = new DataProtectionProvider();

            // Create a random access stream to contain the encrypted message.
            InMemoryRandomAccessStream inputData = new InMemoryRandomAccessStream();

            // Create a random access stream to contain the decrypted data.
            InMemoryRandomAccessStream unprotectedData = new InMemoryRandomAccessStream();

            // Retrieve an IOutputStream object and fill it with the input (encrypted) data.
            IOutputStream outputStream = inputData.GetOutputStreamAt(0);
            DataWriter writer = new DataWriter(outputStream);
            writer.WriteBuffer(buffProtected);
            await writer.StoreAsync();
            await outputStream.FlushAsync();

            // Retrieve an IInputStream object from which you can read the input (encrypted) data.
            IInputStream source = inputData.GetInputStreamAt(0);

            // Retrieve an IOutputStream object and fill it with decrypted data.
            IOutputStream dest = unprotectedData.GetOutputStreamAt(0);
            await Provider.UnprotectStreamAsync(source, dest);
            await dest.FlushAsync();

            // Write the decrypted data to an IBuffer object.
            DataReader reader2 = new DataReader(unprotectedData.GetInputStreamAt(0));
            await reader2.LoadAsync((uint)unprotectedData.Size);
            IBuffer buffUnprotectedData = reader2.ReadBuffer((uint)unprotectedData.Size);

            // Convert the IBuffer object to a string using the same encoding that was
            // used previously to conver the plaintext string (before encryption) to an
            // IBuffer object.
            String strUnprotected = CryptographicBuffer.ConvertBinaryToString(encoding, buffUnprotectedData);

            // Return the decrypted data.
            return strUnprotected;
        }
    }
}