KeyDerivationParameters.BuildForSP80056a Method

Reference

Definition

Namespace:: Windows.Security.Cryptography.Core

Important

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Creates a KeyDerivationParameters object for use in the SP800-56A key derivation function.

public:
 static KeyDerivationParameters ^ BuildForSP80056a(IBuffer ^ algorithmId, IBuffer ^ partyUInfo, IBuffer ^ partyVInfo, IBuffer ^ suppPubInfo, IBuffer ^ suppPrivInfo);

 static KeyDerivationParameters BuildForSP80056a(IBuffer const& algorithmId, IBuffer const& partyUInfo, IBuffer const& partyVInfo, IBuffer const& suppPubInfo, IBuffer const& suppPrivInfo);

public static KeyDerivationParameters BuildForSP80056a(IBuffer algorithmId, IBuffer partyUInfo, IBuffer partyVInfo, IBuffer suppPubInfo, IBuffer suppPrivInfo);

function buildForSP80056a(algorithmId, partyUInfo, partyVInfo, suppPubInfo, suppPrivInfo)

Public Shared Function BuildForSP80056a (algorithmId As IBuffer, partyUInfo As IBuffer, partyVInfo As IBuffer, suppPubInfo As IBuffer, suppPrivInfo As IBuffer) As KeyDerivationParameters

Parameters

algorithmId: IBuffer

Specifies the intended purpose of the derived key.

partyUInfo: IBuffer

Contains public information contributed by the initiator.

partyVInfo: IBuffer

Contains public information contributed by the responder.

suppPubInfo: IBuffer

Contains public information known to both initiator and responder.

suppPrivInfo: IBuffer

Contains private information known to both initiator and responder, such as a shared secret.

Returns

KeyDerivationParameters

Refers to the parameters used during key derivation.

Examples

public void SampleDeriveFromSP80056a()
{
    // Create a string that contains the algorithm name.
    String strAlgName = KeyDerivationAlgorithmNames.Sp80056aConcatSha512;

    // 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 secret to be used during derivation.
    IBuffer buffSecret = CryptographicBuffer.GenerateRandom(32);

    // Create a buffer that contains the intended purpose of the derived key.
    String strAlgId = "Purpose";
    IBuffer buffAlgId = CryptographicBuffer.ConvertStringToBinary(strAlgId, BinaryStringEncoding.Utf8);

    // Create a buffer that contains public information contributed by the initiator.
    String strPartyUInfo = "Initiator public info";
    IBuffer buffPartyUInfo = CryptographicBuffer.ConvertStringToBinary(strPartyUInfo, BinaryStringEncoding.Utf8);

    // Create a buffer that contains public information contributed by the responder.
    String strPartyVInfo = "Responder public info";
    IBuffer buffPartyVInfo = CryptographicBuffer.ConvertStringToBinary(strPartyVInfo, BinaryStringEncoding.Utf8);

    // Create a buffer that contains public information known to both parties.
    String strSuppPubInfo = "Two party public info";
    IBuffer buffSuppPubInfo = CryptographicBuffer.ConvertStringToBinary(strSuppPubInfo, BinaryStringEncoding.Utf8);

    // Create a buffer that contains a shared private secret.
    IBuffer buffSuppPrivInfo = CryptographicBuffer.GenerateRandom(32);

    // Create the derivation parameters.
    KeyDerivationParameters kdf80056AParamsEx = KeyDerivationParameters.BuildForSP80056a(
        buffAlgId,
        buffPartyUInfo,
        buffPartyVInfo,
        buffSuppPubInfo,
        buffSuppPrivInfo);

    // 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,
        kdf80056AParamsEx,
        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 SP80056a KDF algorithm provider:

Applies to

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