<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept xml:lang="en" id="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636"><title>Secure store encryption example code</title><prolog><metadata><keywords/></metadata></prolog><conbody><p>This example covers: </p> <ul><li id="GUID-C08CC80E-FDF5-54FB-A289-2D1C4B4AD982"><p> <xref href="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636.dita#GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636/GUID-3CE75F7F-B812-5010-99E6-50416C207B41">Creating and opening a new secure store protected by the supplied password</xref>  </p> </li> <li id="GUID-67FA0BEE-6BC5-5F49-9CD8-9B81CD25894C"><p> <xref href="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636.dita#GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636/GUID-58FD2C9E-80E8-5F88-AF83-DC0022FE92E7">Opening an existing secure store</xref>  </p> </li> <li id="GUID-F3D2DF1D-A547-594C-BCB8-8BADD69D980D"><p> <xref href="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636.dita#GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636/GUID-6C8BF1E2-E824-539D-A57F-DED436C24C88">Writing some data to a new stream in the currently opened store, and returning the ID of the stream</xref>  </p> </li> <li id="GUID-1B9A3CB6-6ADB-508F-8563-03E17BD7BB02"><p> <xref href="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636.dita#GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636/GUID-A6AF8D9B-6A03-5CA4-BC0E-0296FBC10EDD">Reading the data in a given stream from the currently opened store</xref>  </p> </li> <li id="GUID-51A035CA-16CD-5547-828A-049E3FD20D5B"><p> <xref href="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636.dita#GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636/GUID-2C2E3C02-8F9D-5FA6-8ACA-1CDBA8EA11A9">Closing the currently opened store</xref>  </p> </li> <li id="GUID-1E71B260-5C38-51C7-B535-4A3C6EE210AF"><p> <xref href="GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636.dita#GUID-36BCDD1F-3713-5DF0-8D8A-CF093694B636/GUID-4ABE3513-0B3D-5F17-8F1B-CDA12C5DE370">Changing the password for the currently opened store.</xref>  </p> </li> </ul> <p>Also, see: </p> <ul><li id="GUID-96A01360-DFA8-5FC3-97CD-6B2013756CBC"><p> <xref href="GUID-3385079E-84F4-534F-B937-BD3A568D71BC.dita">PBE example code</xref>  </p> </li> <li id="GUID-2E08A91C-C02C-5DF6-8051-7209E48FDA02"><p> <xref href="GUID-598B6698-3518-50CA-98DE-D85CB255BA2D.dita">Secure stream example code</xref>  </p> </li> </ul> <section id="GUID-3CE75F7F-B812-5010-99E6-50416C207B41"><title>Creating and opening a new secure store protected by the supplied password</title> <ul><li id="GUID-913C5F07-E786-546A-90F6-D26019A52C96"><p> <xref href="GUID-7D53E323-CF8D-5C4D-ABCD-4D95C7A4A5B5.dita">Supporting code for this example</xref>  </p> </li> </ul> <codeblock id="GUID-0BBC7516-B37F-5A01-9853-DFD7B490C931" xml:space="preserve">

void CSecureStoreExample::CreateNewStoreL(const TDesC& aPassword)

         {

         // Check store is not already open

         ASSERT(!iEncryptSet && !iSecureStore && !iFileStore);

         // Create a standard file store

         iFileStore = CPermanentFileStore::ReplaceL(iFs, iFilename, EFileRead | EFileWrite | EFileShareExclusive);

         iFileStore->SetTypeL(KPermanentFileStoreLayoutUid);

         // Create a CPBEncryptSet object (because a store is comprised of multiple

         // independent objects)

         TPBPassword password(aPassword);

         iEncryptSet = CPBEncryptSet::NewL(password, ECipherDES_CBC);

         // Write encryption data and encrypted master key to the root stream of the

         // store.  We need to store both of these pieces of information to be able

         // to access the secure store at a later time.

         RStoreWriteStream writeStream;

         TStreamId rootId = writeStream.CreateLC(*iFileStore);

         writeStream << iEncryptSet->EncryptionData();

         writeStream << iEncryptSet->EncryptedMasterKey();

         writeStream.CommitL();

         CleanupStack::PopAndDestroy(&writeStream);

         iFileStore->SetRootL(rootId);

         iFileStore->CommitL();

         // Create the secure store - this wraps the file store providing transparent

         // encryption/decryption of streams.

         iSecureStore = CSecureStore::NewL(*iFileStore, *iEncryptSet);

         }

            </codeblock> </section> <section id="GUID-58FD2C9E-80E8-5F88-AF83-DC0022FE92E7"><title>Opening an existing secure store</title> <ul><li id="GUID-9B07EB34-D2C1-53FF-8338-3F18A235ADC5"><p> <xref href="GUID-7D53E323-CF8D-5C4D-ABCD-4D95C7A4A5B5.dita">Supporting code for this example</xref>  </p> </li> </ul> <codeblock id="GUID-6EDC3451-A2DF-537F-BF71-1A4925462790" xml:space="preserve">

// Leaves with KErrBadPassphrase if the password is 

// not the same as the one used when creating the store.

void CSecureStoreExample::OpenExistingStoreL(const TDesC& aPassword)

         {

         // Check store is not already open

         ASSERT(!iEncryptSet && !iSecureStore && !iFileStore);

         // Open a standard file store

         iFileStore = CPermanentFileStore::OpenL(iFs, iFilename, EFileRead | EFileWrite | EFileShareExclusive);

         // Read the encryption data and encrypted master key from the root stream

         TStreamId rootId = iFileStore->Root();

         RStoreReadStream readStream;

         readStream.OpenLC(*iFileStore, rootId);

         CPBEncryptionData* encryptionData = CPBEncryptionData::NewLC(readStream);

         HBufC8* encryptedMasterKey = HBufC8::NewLC(readStream, KMaxTInt);

         // Use these to recreate the CPBEncryptSet object (this leaves if

         // aPassword is wrong)

         iEncryptSet = CPBEncryptSet::NewL(*encryptionData, *encryptedMasterKey, aPassword);

         // Create the secure store

         iSecureStore = CSecureStore::NewL(*iFileStore, *iEncryptSet);

         // Free memory

         CleanupStack::PopAndDestroy(3, &readStream);

         }

            </codeblock> </section> <section id="GUID-6C8BF1E2-E824-539D-A57F-DED436C24C88"><title>Writing some data to a new stream in the currently opened store, and returning the ID of the stream</title> <ul><li id="GUID-1FF9BA5F-296F-5AF7-9737-A95B9059061E"><p> <xref href="GUID-7D53E323-CF8D-5C4D-ABCD-4D95C7A4A5B5.dita">Supporting code for this example</xref>  </p> </li> </ul> <codeblock id="GUID-F8539B5E-197A-5FAF-B908-4EAD26BA2A6A" xml:space="preserve">

TStreamId CSecureStoreExample::WriteEncryptedDataL(const TDesC8& aInput)

         {

         // Check store is open

         ASSERT(iEncryptSet && iSecureStore && iFileStore);

         // Create a new stream in the store 

         RStoreWriteStream writeStream;

         TStreamId newStreamId = writeStream.CreateLC(*iSecureStore);

         // Write data - this is automatically encrypted

         writeStream << aInput;

         writeStream.CommitL();

         iSecureStore->CommitL();

         CleanupStack::PopAndDestroy(&writeStream);

         return newStreamId;

         }

            </codeblock> </section> <section id="GUID-A6AF8D9B-6A03-5CA4-BC0E-0296FBC10EDD"><title>Reading the data in a given stream from the currently opened store</title> <ul><li id="GUID-8F696865-A038-5649-ACCF-030A482C5C3A"><p> <xref href="GUID-7D53E323-CF8D-5C4D-ABCD-4D95C7A4A5B5.dita">Supporting code for this example</xref>  </p> </li> </ul> <codeblock id="GUID-DC1CABBD-2D1A-5A94-B28E-73C9F94A579E" xml:space="preserve">

HBufC8* CSecureStoreExample::ReadEncryptedDataLC(TStreamId aStreamId)

         {

         // Check store is open

         ASSERT(iEncryptSet && iSecureStore && iFileStore);

         // Open an existing stream in the store

         RStoreReadStream readStream;

         readStream.OpenLC(*iSecureStore, aStreamId);

         // Read data - this is automatically decrypted

         HBufC8* output = HBufC8::NewL(readStream, KMaxTInt);

         CleanupStack::PopAndDestroy(&readStream);

         CleanupStack::PushL(output);

         return output;

         }

            </codeblock> </section> <section id="GUID-2C2E3C02-8F9D-5FA6-8ACA-1CDBA8EA11A9"><title>Closing the currently opened store</title> <ul><li id="GUID-6C2360BE-435D-5350-8149-AAF679A441D7"><p> <xref href="GUID-7D53E323-CF8D-5C4D-ABCD-4D95C7A4A5B5.dita">Supporting code for this example</xref>  </p> </li> </ul> <codeblock id="GUID-253A7771-4030-5393-83B9-10D4538A0CC6" xml:space="preserve">

void CSecureStoreExample::CloseStore()

         {

         delete iSecureStore;

         iSecureStore = NULL;

         delete iEncryptSet;

         iEncryptSet = NULL;

         delete iFileStore;

         iFileStore = NULL;

         }

            </codeblock> </section> <section id="GUID-4ABE3513-0B3D-5F17-8F1B-CDA12C5DE370"><title>Changing the password for the currently opened store</title> <ul><li id="GUID-DFBC3396-7564-5647-8B6C-525F46FA6512"><p> <xref href="GUID-7D53E323-CF8D-5C4D-ABCD-4D95C7A4A5B5.dita">Supporting code for this example</xref>  </p> </li> </ul> <codeblock id="GUID-D7A38D85-EAC1-579F-8ECB-F7420A21E519" xml:space="preserve">

void CSecureStoreExample::ChangePasswordL(const TDesC& aNewPassword)

         {

         // Check store is open

         ASSERT(iEncryptSet && iSecureStore && iFileStore);

         // Change password on encrypt set object

         iEncryptSet->ChangePasswordL(aNewPassword);

         // Must now rewrite data in root stream

         TStreamId rootId = iFileStore->Root();

         RStoreWriteStream writeStream;

         writeStream.ReplaceLC(*iFileStore, rootId);

         writeStream << iEncryptSet->EncryptionData();

         writeStream << iEncryptSet->EncryptedMasterKey();

         writeStream.CommitL();

         iFileStore->CommitL();

         CleanupStack::PopAndDestroy(&writeStream);

         }

            </codeblock> </section> </conbody></concept>