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<task id="GUID-EFF8D1A1-00D5-5F96-8285-414DC0044AB8" xml:lang="en"><title>Setting
Use Policies</title><shortdesc>A use policy denotes the security check required to use the key.
The use policy associated with the key is of type <apiname>TSecurityPolicy</apiname>.
The policy can be set to check capabilities or the Secure ID associated with
the calling process. The calling process should have a <codeph>WriteUserData</codeph> capability. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
<context><p>The following steps explain the process of setting a use policy
for a key:</p></context>
<steps id="GUID-16DDA72F-9BC5-52FB-A3C6-874815ABF9FC-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-2">
<step id="GUID-89755D62-9A44-5F07-9035-6AA97F701C0C-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-2-1"><cmd>Create a file system
session using an <codeph>RFs</codeph> object. </cmd>
</step>
<step id="GUID-6A14EBD6-AF2D-5CE8-A232-F04B717CA0B3-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-2-2"><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-C8F104CE-E857-5615-B847-E3A33EAF7481-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-2-3"><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-B1DD3DB8-90D9-52F7-96B5-B2AD5AE3E1F8"><cmd/>
<info>List all keys in the keystore using the <xref href="GUID-818689D6-EB99-382E-A435-D9C6C5D464DE.dita#GUID-818689D6-EB99-382E-A435-D9C6C5D464DE/GUID-8B22E1BC-D779-32DC-9C0A-CA37E4C0A81B"><apiname>CUnifiedKeyStore::List()</apiname></xref> function.
Retrieve the handle of the key for which the use policy needs to be set. </info>
</step>
<step id="GUID-6CF7703F-8CAC-5DC6-9F43-7E2EE3F39895-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-2-5"><cmd/>
<info>Set the use policy for the key using the <xref href="GUID-818689D6-EB99-382E-A435-D9C6C5D464DE.dita#GUID-818689D6-EB99-382E-A435-D9C6C5D464DE/GUID-CC8814B6-569C-3426-A319-BFB631211B07"><apiname>CUnifiedKeyStore::SetUsePolicy()</apiname></xref> function. </info>
</step>
</steps>
<result><p>Use policy is set for the selected key. </p> </result>
<example id="GUID-C2150584-293D-50CE-8DDC-19B4D55D8B0B-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-4"><title>Example</title> <p>The
following code snippet shows how to set use policy for a key. </p> <codeblock id="GUID-FAD1C292-8E42-5348-B975-3CBA7E8D2820-GENID-1-6-1-22-1-1-8-1-5-1-5-1-5-1-4-1-12-1-3-4-3" xml:space="preserve">// Create a file system session object
RFs iFs;
CleanupClosePushL(&amp;iFs);


...


// Initialise the keystore and member functions
CUnifiedKeyStore* keyStore = CUnifiedKeyStore::NewL(fs);
keyStore-&gt;Initialize(iStatus); //iStatus is a TRequestStatus object


...



// Retrieve the handle of the key for which use policy has to be set
TCTKeyAttributeFilter  filter.iUsage = EPKCS15UsageAll;
RPointerArray&lt;CCTKeyInfo&gt; iKeys; // This variable will contain the result of the set use policy operation
keyStore-&gt;List(iKeys, filter, iStatus);


...



// Retrieve the key handle of the appropriate key
_LIT(KLabel,”keylabel”);

// Select the key with the label you are looking for
TInt keyIndex;
for (TInt j = 0; j &lt; iKeys.Count(); j++)
    {
    if (iKeys[j]-&gt;Label() == KLabel) 
        {
        keyIndex = j;
        break;
        }
    }


...



// Set the use policy

TSecurityPolicy usePolicy;
TUint secureId = 0x101FFFFF;
TCapability caps[3];
caps[0] = ECapabilityWriteUserData;
caps[1] = ECapabilityDRM;
caps[2] = ECapabilityReadUserData;

usePolicy = TSecurityPolicy(TSecureId(secureId), caps[0], caps[1], caps[2]);
keyStore-&gt;SetUsePolicy(*iKeys, usePolicy, iStatus);


// Clean up
CleanupStack::PopAndDestroy(); // iFs</codeblock> </example>
</taskbody><related-links>
<link href="GUID-60141F31-6061-5C65-809D-FE7A4F8414F7.dita"><linktext>Set Management
Policies</linktext></link>
</related-links></task>