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<task id="GUID-F446E658-B717-5257-9C5C-442B07B19565" xml:lang="en"><title> Performing

Cryptographic Operations with Keys</title><abstract><p>You can use various types of algorithms (for example RSA sign,

DSA sign, Decrypt, DH key agreement, and so on) to perform cryptographic operations

with keys in the unified keystore. This section provides information on the

signing process. </p><p> The following steps explain the process of signing

keys by considering the example of an RSA signing operation:</p></abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>

<steps id="GUID-E7265950-3F94-51A6-BD6E-E99A25152E0B">

<step id="GUID-98896CA9-D5F6-5FCD-92B8-627D701DD080"><cmd/>

<info>Create an object of type CUnifiedKeyStore using <xref href="GUID-818689D6-EB99-382E-A435-D9C6C5D464DE.dita#GUID-818689D6-EB99-382E-A435-D9C6C5D464DE/GUID-C7A96153-4179-3B3F-878D-1EAA64A98D39"><apiname>CUnifiedKeyStore::NewL()</apiname></xref> or <xref href="GUID-818689D6-EB99-382E-A435-D9C6C5D464DE.dita#GUID-818689D6-EB99-382E-A435-D9C6C5D464DE/GUID-217FBB3B-CEF5-36F2-A612-EDDA0982053C"><apiname>CUnifiedKeyStore::NewLC()</apiname></xref>. </info>

</step>

<step id="GUID-3CFD0F4D-5467-5FE5-9003-F16FDF6750B1"><cmd/>

<info>Initialise the member functions and keystore using the asynchronous

function <xref href="GUID-818689D6-EB99-382E-A435-D9C6C5D464DE.dita#GUID-818689D6-EB99-382E-A435-D9C6C5D464DE/GUID-6C5D732C-1FD1-3EF0-AC90-87690F891B8D"><apiname>CUnifiedKeyStore::Initialize()</apiname></xref>. </info>

</step>

<step id="GUID-73A277E5-45B8-5F87-B114-2004AE4DD4C5"><cmd/>

<info>List all the keys in the keystore and then retrieve the key to be signed

based on filter criteria. </info>

</step>

<step id="GUID-036E7985-FB51-52C5-BC27-4ADAD38E0923"><cmd>Invoke the <codeph>MKeyStore::Open()</codeph> function

for opening the key. This also enables the creation of an object capable of

performing the required signing operation. In the case of an RSA signing process,

the key is opened to create a <codeph>MRSASigner</codeph> object. </cmd>

<info> Note: The following table lists the objects created for different cryptographic

operations: </info>

<stepxmp><table id="GUID-0DE1BD27-AF6F-5CC1-8A9E-9D36380D4EBE">

<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

<tbody>

<row>

<entry><p> <b>Operation</b>  </p> </entry>

<entry><p> <b>Object</b>  </p> </entry>

</row>

<row>

<entry><p>DSA Sign </p> </entry>

<entry><p> <codeph>MDSASigner</codeph>  </p> </entry>

</row>

<row>

<entry><p>Decrypt </p> </entry>

<entry><p> <codeph>MCTDecryptor</codeph>  </p> </entry>

</row>

<row>

<entry><p>DH Key Agreement </p> </entry>

<entry><p> <codeph>MCTDH</codeph>  </p> </entry>

</row>

</tbody>

</tgroup>

</table> </stepxmp>

</step>

<step id="GUID-D3E1854A-D798-5CB5-B528-AB5F672C2AC7"><cmd/>

<info>Use <codeph>MCTSigner::SignMessage()</codeph> or <codeph>MCTSigner::Sign()</codeph> to

perform the signing operation. </info>

</step>

</steps>

<result><p>The <codeph>CRSASignature</codeph> object contains the value of

the signing operation. </p> </result>

<example><p>The following code snippet shows RSA signing operation: </p><codeblock id="GUID-B7FA7CF8-38D6-5088-B51E-73AB04139997" xml:space="preserve">

//Create a file system session object

RFs iFs;

CleanupClosePushL(&iFs);

//Initialise the keystore and member functions

CUnifiedKeyStore* keyStore = CUnifiedKeyStore::NewL(fs);

keyStore->Initialize(iStatus); //iStatus is a TRequestStatus object

...

// Create a filter to retrieve all keys from the store

TCTKeyAttributeFilter filter;

filter.iPolicyFilter = TCTKeyAttributeFilter:EAllKeys;

// Retrieve a list of all the keys from the key store

RPointerArray<CCTKeyInfo> iKeys; // This variable will contain the key to be signed

iKeyStore->List(iKeys,filter,iStatus);

...

// Retrieve the key based on the label you are looking for 

_LIT(Klabel,”keylabel”);

TInt keyCount = iKeys.Count();

for (i = 0; i < keyCount; i++)

{

    CCTKeyInfo* keyInfo = iKeys[i];

    if (keyInfo->Label() == Klabel)

        {

            // Create a signer object for the key

            MRSASigner* iRSASigner

            // The signer object will be returned after the key has been opened for signing

            keyStore->Open(*keyInfo, iRSASigner, iStatus);

            break;

        }

}

// Perform the signing operation

// Define the data for signing

HBufC* dataToSign; 

dataToSign = HBufC::NewL(20);

_LIT(KTxtSign,"Data to be signed");

*dataToSign = KTxtSign; 

CRSASignature* iRSASignature;

// iRSASignature will contain the result after the completion

// of the following request

iRSASigner->SignMessage(*dataToSign, iRSASignature, iStatus);

...

// Retrieve the RSA signature value through the CRSASignature object 

TInt signature = iRSASignature->S();

</codeblock></example>

</taskbody><related-links>

<link href="GUID-C4389D60-2A8D-532D-9D92-E57B0CCD14CF.dita"><linktext>Unified Keystore</linktext>

</link>