KeyDerivationParameters.BuildForSP800108(IBuffer, IBuffer) Method

Reference

Definition

Namespace:: Windows.Security.Cryptography.Core

Important

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Edit

Creates a KeyDerivationParameters object for use in a counter mode, hash-based message authentication code (HMAC) key derivation function.

public:
 static KeyDerivationParameters ^ BuildForSP800108(IBuffer ^ label, IBuffer ^ context);

 static KeyDerivationParameters BuildForSP800108(IBuffer const& label, IBuffer const& context);

public static KeyDerivationParameters BuildForSP800108(IBuffer label, IBuffer context);

function buildForSP800108(label, context)

Public Shared Function BuildForSP800108 (label As IBuffer, context As IBuffer) As KeyDerivationParameters

Parameters

label: IBuffer

Buffer that specifies the purpose for the derived keying material.

context: IBuffer

Buffer that specifies information related to the derived keying material. For example, the context can identify the parties who are deriving the keying material and, optionally, a nonce known by the parties.

Returns

KeyDerivationParameters

Refers to the parameters used during key derivation.

Examples

public void SampleDeriveFromSP800108()
{
    // Create a string that contains the algorithm name.
    String strAlgName = KeyDerivationAlgorithmNames.Sp800108CtrHmacSha256;

    // Open the specified algorithm.
    KeyDerivationAlgorithmProvider objKdfProv = KeyDerivationAlgorithmProvider.OpenAlgorithm(strAlgName);

    // Specify the requested size, in bytes, of the derived key. 
    UInt32 targetSize = 32;

    // Create a buffer that contains the label value.
    String strPurpose = "Purpose";
    IBuffer buffLabel = CryptographicBuffer.ConvertStringToBinary(strPurpose, BinaryStringEncoding.Utf8);

    // Create a buffer that contains the context value.
    byte[] Nonce = { 1, 1, 0, 0, 0, 0, 0, 0};
    IBuffer buffContext = CryptographicBuffer.CreateFromByteArray(Nonce);

    // Create the derivation parameters.
    KeyDerivationParameters kdf800108Params = KeyDerivationParameters.BuildForSP800108(buffLabel, buffContext);

    // Create a secret value.
    IBuffer buffSecret = CryptographicBuffer.GenerateRandom(32);

    // Create a key from the secret value.
    CryptographicKey keyOriginal = objKdfProv.CreateKey(buffSecret);

    // Derive a key based on the original key and the derivation parameters.
    IBuffer keyDerived = CryptographicEngine.DeriveKeyMaterial(
        keyOriginal,
        kdf800108Params,
        targetSize);

    // Encode the key to a hexadecimal value (for display)
    String strKeyHex = CryptographicBuffer.EncodeToHexString(keyDerived);
}

Remarks

You can use the following algorithm names with the OpenAlgorithm function to open a SP800108 KDF algorithm provider:

Applies to

Jaa