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Secure store encryption example code

This example covers:

Also, see:

Creating and opening a new secure store protected by the supplied password

Supporting code for this example


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);
         }

Opening an existing secure store

Supporting code for this example


// 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);
         }

Writing some data to a new stream in the currently opened store, and returning the ID of the stream

Supporting code for this example


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;
         }

Reading the data in a given stream from the currently opened store

Supporting code for this example


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;
         }

Closing the currently opened store

Supporting code for this example


void CSecureStoreExample::CloseStore()
         {
         delete iSecureStore;
         iSecureStore = NULL;
         delete iEncryptSet;
         iEncryptSet = NULL;
         delete iFileStore;
         iFileStore = NULL;
         }

Changing the password for the currently opened store

Supporting code for this example


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);
         }

Parent topic: Example code