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SymmetricKeyAlgorithmProvider Classe

Définition

Représente un fournisseur d’algorithmes de clé symétrique. Pour plus d’informations, consultez Clés de chiffrement.

public ref class SymmetricKeyAlgorithmProvider sealed
/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 65536)]
/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
/// [Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
class SymmetricKeyAlgorithmProvider final
[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 65536)]
[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
[Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
public sealed class SymmetricKeyAlgorithmProvider
Public NotInheritable Class SymmetricKeyAlgorithmProvider
Héritage
Object Platform::Object IInspectable SymmetricKeyAlgorithmProvider
Attributs

Configuration requise pour Windows

Famille d’appareils
Windows 10 (introduit dans 10.0.10240.0)
API contract
Windows.Foundation.UniversalApiContract (introduit dans v1.0)

Exemples

using Windows.Security.Cryptography;
using Windows.Security.Cryptography.Core;
using Windows.Storage.Streams;

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

            // Initialize the encryption process.
            String strMsg = "1234567812345678";     // Data to encrypt.
            String strAlgName = SymmetricAlgorithmNames.AesCbc;
            UInt32 keyLength = 32;                  // Length of the key, in bytes
            BinaryStringEncoding encoding;          // Binary encoding value
            IBuffer iv;                             // Initialization vector
            CryptographicKey key;                   // Symmetric key

            // Encrypt a message.
            IBuffer buffEncrypted = this.SampleCipherEncryption(
                strMsg,
                strAlgName,
                keyLength,
                out encoding,
                out iv,
                out key);

            // Decrypt a message.
            this.SampleCipherDecryption(
                strAlgName,
                buffEncrypted,
                iv,
                encoding,
                key);
        }

        public IBuffer SampleCipherEncryption(
            String strMsg,
            String strAlgName,
            UInt32 keyLength,
            out BinaryStringEncoding encoding,
            out IBuffer iv,
            out CryptographicKey key)
        {
            // Initialize the initialization vector.
            iv = null;

            // Initialize the binary encoding value.
            encoding = BinaryStringEncoding.Utf8;

            // Create a buffer that contains the encoded message to be encrypted. 
            IBuffer buffMsg = CryptographicBuffer.ConvertStringToBinary(strMsg, encoding);

            // Open a symmetric algorithm provider for the specified algorithm. 
            SymmetricKeyAlgorithmProvider objAlg = SymmetricKeyAlgorithmProvider.OpenAlgorithm(strAlgName);

            // Demonstrate how to retrieve the name of the algorithm used.
            String strAlgNameUsed = objAlg.AlgorithmName;

            // Determine whether the message length is a multiple of the block length.
            // This is not necessary for PKCS #7 algorithms which automatically pad the
            // message to an appropriate length.
            if (!strAlgName.Contains("PKCS7"))
            {
               if ((buffMsg.Length % objAlg.BlockLength) != 0)
                {
                    throw new Exception("Message buffer length must be multiple of block length.");
                }
            }

            // Create a symmetric key.
            IBuffer keyMaterial = CryptographicBuffer.GenerateRandom(keyLength);
            key = objAlg.CreateSymmetricKey(keyMaterial);

            // CBC algorithms require an initialization vector. Here, a random
            // number is used for the vector.
            if (strAlgName.Contains("CBC"))
            {
                iv = CryptographicBuffer.GenerateRandom(objAlg.BlockLength);
            }

            // Encrypt the data and return.
            IBuffer buffEncrypt = CryptographicEngine.Encrypt(key, buffMsg, iv);
            return buffEncrypt;
        }

        public void SampleCipherDecryption(
            String strAlgName,
            IBuffer buffEncrypt,
            IBuffer iv,
            BinaryStringEncoding encoding,
            CryptographicKey key)
        {
            // Declare a buffer to contain the decrypted data.
            IBuffer buffDecrypted;

            // Open an symmetric algorithm provider for the specified algorithm. 
            SymmetricKeyAlgorithmProvider objAlg = SymmetricKeyAlgorithmProvider.OpenAlgorithm(strAlgName);

            // The input key must be securely shared between the sender of the encrypted message
            // and the recipient. The initialization vector must also be shared but does not
            // need to be shared in a secure manner. If the sender encodes a message string 
            // to a buffer, the binary encoding method must also be shared with the recipient.
            buffDecrypted = CryptographicEngine.Decrypt(key, buffEncrypt, iv);

            // Convert the decrypted buffer to a string (for display). If the sender created the
            // original message buffer from a string, the sender must tell the recipient what 
            // BinaryStringEncoding value was used. Here, BinaryStringEncoding.Utf8 is used to
            // convert the message to a buffer before encryption and to convert the decrypted
            // buffer back to the original plaintext.
            String strDecrypted = CryptographicBuffer.ConvertBinaryToString(encoding, buffDecrypted);
        }
    }
}

Remarques

Vous créez un objet SymmetricKeyAlgorithmProvider en appelant la méthode OpenAlgorithm statique et en spécifiant l’un des noms d’algorithmes suivants.

  • Aucun remplissage :+ DES_CBC

  • DES_ECB

  • 3DES_CBC

  • 3DES_ECB

  • RC2_CBC

  • RC2_ECB

  • AES_CBC

  • AES_ECB

  • Modes de remplissage de blocs PKCS#7 :+ AES_CBC_PKCS7

  • AES_ECB_PKCS7

  • DES_CBC_PKCS7

  • DES_ECB_PKCS7

  • 3DES_CBC_PKCS7

  • 3DES_ECB_PKCS7

  • RC2_CBC_PKCS7

  • RC2_ECB_PKCS7

  • Modes authentifiés (voir la classe EncryptedAndAuthenticatedData ) :+ AES_GCM

  • AES_CCM

  • Chiffrement de flux :+ RC4

Propriétés

AlgorithmName

Obtient le nom de l’algorithme symétrique ouvert.

BlockLength

Obtient la taille, en octets, du bloc de chiffrement pour l’algorithme ouvert.

Méthodes

CreateSymmetricKey(IBuffer)

Crée une clé symétrique.

OpenAlgorithm(String)

Crée une instance de la classe SymmetricKeyAlgorithmProvider et ouvre l’algorithme spécifié à utiliser.

S’applique à

Voir aussi