SymmetricKeyAlgorithmProvider SymmetricKeyAlgorithmProvider SymmetricKeyAlgorithmProvider SymmetricKeyAlgorithmProvider SymmetricKeyAlgorithmProvider Class


Represents a provider of symmetric key algorithms. For more information, see Cryptographic keys.

public : sealed class SymmetricKeyAlgorithmProvider
struct winrt::Windows::Security::Cryptography::Core::SymmetricKeyAlgorithmProvider
public sealed class SymmetricKeyAlgorithmProvider
Public NotInheritable Class SymmetricKeyAlgorithmProvider
// This class does not provide a public constructor.

Windows 10 requirements

Device family
Windows 10 (introduced v10.0.10240.0)
API contract
Windows.Foundation.UniversalApiContract (introduced v1)


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.

            // 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(
                out encoding,
                out iv,
                out key);

            // Decrypt a message.

        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);


You create a SymmetricKeyAlgorithmProvider object by calling the static OpenAlgorithm method and specifying one of the following algorithm names.

  • No padding:+ DES_CBC


  • 3DES_CBC

  • 3DES_ECB

  • RC2_CBC

  • RC2_ECB



  • PKCS#7 block padding modes:+ AES_CBC_PKCS7








  • Authenticated modes (see the EncryptedAndAuthenticatedData class):+ AES_GCM


  • Stream Cipher:+ RC4


AlgorithmName AlgorithmName AlgorithmName AlgorithmName AlgorithmName

Gets the name of the open symmetric algorithm.

BlockLength BlockLength BlockLength BlockLength BlockLength

Gets the size, in bytes, of the cipher block for the open algorithm.


CreateSymmetricKey(IBuffer) CreateSymmetricKey(IBuffer) CreateSymmetricKey(IBuffer) CreateSymmetricKey(IBuffer) CreateSymmetricKey(IBuffer)

Creates a symmetric key.

OpenAlgorithm(String) OpenAlgorithm(String) OpenAlgorithm(String) OpenAlgorithm(String) OpenAlgorithm(String)

Creates an instance of the SymmetricKeyAlgorithmProvider class and opens the specified algorithm for use.

See also