Protection des données
Cet article explique comment utiliser la classe DataProtectionProvider dans l’espace de noms Windows.Security.Cryptography.DataProtection pour chiffrer et déchiffrer des données numériques dans une application UWP.
Vous pouvez utiliser les API de protection des données de plusieurs façons :
- Pour protéger les données vers un principal de sécurité Active Directory (AD) comme un groupe AD. Tout membre du groupe peut déchiffrer les données.
- Pour protéger les données sur la clé publique contenue dans un certificat X.509. Le propriétaire de la clé privée peut déchiffrer les données.
- Pour protéger les données à l’aide d’une clé symétrique. Cela fonctionne, par exemple, pour protéger les données sur un principal non AD tel que Live ID.
- Pour protéger les données des informations d’identification (mot de passe) utilisées lors de l’ouverture de session sur un site web.
Pour protéger les données, lorsque vous créez un objet DataProtectionProvider, vous devez spécifier un descripteur de protection avant d’appeler ProtectAsync ou ProtectStreamAsync. L’exemple suivant montre des exemples de descripteurs de protection possibles.
Protection des données statiques
L’exemple suivant montre comment utiliser les méthodes ProtectAsync et UnprotectAsync pour protéger de manière asynchrone les données statiques sur le SID de l’utilisateur actuel.
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;
}
}
}
Protection des données de flux
L’exemple suivant montre comment utiliser les méthodes ProtectStreamAsync et UnprotectStreamAsync pour protéger de manière asynchrone les données de flux vers le SID de l’utilisateur actuel.
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;
}
}
}