MacAlgorithmProvider MacAlgorithmProvider MacAlgorithmProvider MacAlgorithmProvider Class

Definition

public : sealed class MacAlgorithmProvider : IMacAlgorithmProvider, IMacAlgorithmProvider2public sealed class MacAlgorithmProvider : IMacAlgorithmProvider, IMacAlgorithmProvider2Public NotInheritable Class MacAlgorithmProvider Implements IMacAlgorithmProvider, IMacAlgorithmProvider2// You can use this class in JavaScript.

Attributes

ContractVersionAttribute DualApiPartitionAttribute MarshalingBehaviorAttribute StaticAttribute ThreadingAttribute

Examples

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

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

            // Initialize the hashing process.
            String strMsg = "This is a message to be authenticated";
            String strAlgName = MacAlgorithmNames.HmacSha384;
            IBuffer buffMsg;
            CryptographicKey hmacKey;
            IBuffer buffHMAC;

            // Create a hashed message authentication code (HMAC)
            this.CreateHMAC(
                strMsg,
                strAlgName,
                out buffMsg,
                out hmacKey,
                out buffHMAC);

            // Verify the HMAC.
            this.VerifyHMAC(
                buffMsg,
                hmacKey,
                buffHMAC);
        }

        void CreateHMAC(
            String strMsg,
            String strAlgName,
            out IBuffer buffMsg,
            out CryptographicKey hmacKey,
            out IBuffer buffHMAC)
        {
            // Create a MacAlgorithmProvider object for the specified algorithm.
            MacAlgorithmProvider objMacProv = MacAlgorithmProvider.OpenAlgorithm(strAlgName);

            // Demonstrate how to retrieve the name of the algorithm used.
            String strNameUsed = objMacProv.AlgorithmName;

            // Create a buffer that contains the message to be signed.
            BinaryStringEncoding encoding = BinaryStringEncoding.Utf8;
            buffMsg = CryptographicBuffer.ConvertStringToBinary(strMsg, encoding);

            // Create a key to be signed with the message.
            IBuffer buffKeyMaterial = CryptographicBuffer.GenerateRandom(objMacProv.MacLength);
            hmacKey = objMacProv.CreateKey(buffKeyMaterial);

            // Sign the key and message together.
            buffHMAC = CryptographicEngine.Sign(hmacKey, buffMsg);

            // Verify that the HMAC length is correct for the selected algorithm
            if (buffHMAC.Length != objMacProv.MacLength)
            {
                throw new Exception("Error computing digest");
            }
         }

        public void VerifyHMAC(
            IBuffer buffMsg,
            CryptographicKey hmacKey,
            IBuffer buffHMAC)
        {
            // The input key must be securely shared between the sender of the HMAC and 
            // the recipient. The recipient uses the CryptographicEngine.VerifySignature() 
            // method as follows to verify that the message has not been altered in transit.
            Boolean IsAuthenticated = CryptographicEngine.VerifySignature(hmacKey, buffMsg, buffHMAC);
            if (!IsAuthenticated)
            {
                throw new Exception("The message cannot be verified.");
            }
        }
    }
}

Remarks

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

• HMAC_MD5
• HMAC_SHA1
• HMAC_SHA256
• HMAC_SHA384
• HMAC_SHA512
• AES_CMAC

public : PlatForm::String AlgorithmName { get; }public string AlgorithmName { get; }Public ReadOnly Property AlgorithmName As string// You can use this property in JavaScript.

public : unsigned int MacLength { get; }public uint MacLength { get; }Public ReadOnly Property MacLength As uint// You can use this property in JavaScript.

public : CryptographicHash CreateHash(IBuffer keyMaterial)public CryptographicHash CreateHash(IBuffer keyMaterial)Public Function CreateHash(keyMaterial As IBuffer) As CryptographicHash// You can use this method in JavaScript.

public : CryptographicKey CreateKey(IBuffer keyMaterial)public CryptographicKey CreateKey(IBuffer keyMaterial)Public Function CreateKey(keyMaterial As IBuffer) As CryptographicKey// You can use this method in JavaScript.

public : static MacAlgorithmProvider OpenAlgorithm(PlatForm::String algorithm)public static MacAlgorithmProvider OpenAlgorithm(String algorithm)Public Static Function OpenAlgorithm(algorithm As String) As MacAlgorithmProvider// You can use this method in JavaScript.