SymmetricKeyAlgorithmProvider 類別

定義

命名空間:

Windows.Security.Cryptography.Core

表示對稱金鑰演算法的提供者。 如需詳細資訊，請參閱 密碼編譯金鑰。

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

繼承

Object Platform::Object IInspectable SymmetricKeyAlgorithmProvider

屬性

ContractVersionAttribute MarshalingBehaviorAttribute ThreadingAttribute

Windows 需求

裝置系列	Windows 10 (已於 10.0.10240.0 引進)
API contract	Windows.Foundation.UniversalApiContract (已於 v1.0 引進)

範例

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);
        }
    }
}

備註

您可以呼叫靜態 OpenAlgorithm 方法來建立 SymmetricKeyAlgorithmProvider 物件，並指定下列其中一個演算法名稱。

• 沒有填補：+ DES_CBC

• DES_ECB

• 3DES_CBC

• 3DES_ECB

• RC2_CBC

• RC2_ECB

• AES_CBC

• AES_ECB

• PKCS#7 區塊填補模式：+ AES_CBC_PKCS7

• AES_ECB_PKCS7

• DES_CBC_PKCS7

• DES_ECB_PKCS7

• 3DES_CBC_PKCS7

• 3DES_ECB_PKCS7

• RC2_CBC_PKCS7

• RC2_ECB_PKCS7

• 驗證模式 (請參閱 EncryptedAndAuthenticatedData 類別) ：+ AES_GCM

• AES_CCM

• 資料流程加密：+ RC4

屬性

AlgorithmName	取得開放式對稱演算法的名稱。
BlockLength	取得開啟演算法之加密區塊的大小，以位元組為單位。

方法

CreateSymmetricKey(IBuffer)	建立對稱金鑰。
OpenAlgorithm(String)	建立 SymmetricKeyAlgorithmProvider 類別的實例，並開啟要使用的指定演算法。

另請參閱

• AsymmetricKeyAlgorithmProvider
• CryptographicEngine
• CryptographicKey