/**

@page pbe_example_code PBE example code

	This example covers: 

		-# @ref pbe_example_1 "Encrypting some data with a password and writing it to a file"

		-# @ref pbe_example_2 "Reading the data back from the file and decrypting it with the same password".

	<i>This example code is really for reference only - it would be better to use:</i>

		- @ref secure_stream_example_code

		- @ref secure_store_example_code	

<hr>

	- @ref pbe_example_code_support "Supporting code for this example".

@anchor pbe_example_1

@code

/*

 * Encrypt data with password and write it to a file.

 */

void CPBEExample::WriteEncryptedDataL(const TDesC8& aInput, const TDesC& aFilename, const TDesC& aPassword)

		 {

		 // Open a stream to the output file

		 RFileWriteStream writeStream;

		 User::LeaveIfError(writeStream.Replace(iFs, aFilename, EFileShareExclusive | EFileWrite));

		 CleanupClosePushL(writeStream);

		 // Create a CPBEncryptElement object, passing details of the encryption we

		 // are using and the user's password

		 CPBEncryptElement* encryption = CPBEncryptElement::NewLC(aPassword, ECipherDES_CBC);

		 // This is used to create a CPBEncryptor object

		 CPBEncryptor* encryptor = encryption->NewEncryptLC();

		 // Create a buffer of appropriate size to hold the ciphertext

		 HBufC8* ciphertextTemp = HBufC8::NewLC(encryptor->MaxFinalOutputLength(aInput.Length()));

		 TPtr8 ciphertext = ciphertextTemp->Des();		 

		 // Encrypt the input data into the ciphertext buffer

		 encryptor->ProcessFinalL(aInput, ciphertext);

		 // Store encryption data.  This contains details of the encryption used (e.g.,

		 // cipher, key size) as well as things like the salt.  This must be stored

		 // along with the encrypted data, otherwise it is not possible to decrypt it

		 // again!

		 writeStream << encryption->EncryptionData();

		 // Store the ciphertext

		 writeStream << ciphertext;

		 // Commit the stream

		 writeStream.CommitL();

		 // Free memory (writeStream, encryption, encryptor, ciphertextTemp)

		 CleanupStack::PopAndDestroy(4, &writeStream);

		 }

@endcode

@anchor pbe_example_2

@code

/*

 * Read data from file and decrypt it.

 */

HBufC8* CPBEExample::ReadEncryptedDataLC(const TDesC& aFilename, const TDesC& aPassword)

		 {

		 // Open a stream to the input file

		 RFileReadStream readStream;

		 User::LeaveIfError(readStream.Open(iFs, aFilename, EFileRead));

		 CleanupClosePushL(readStream);

		 // Read the encryption data from the file

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

		 // Recreate the CPBEncryptElement object, using the encryption data from the

		 // file and the user's password.  This will leave with KErrBadPassphrase if

		 // the password is wrong.

		 CPBEncryptElement* encryption = CPBEncryptElement::NewLC(*encryptionData, aPassword);

		 // This is used to create a CPBDecryptor object

		 CPBDecryptor* decryptor = encryption->NewDecryptLC();

		 // Read the ciphertext

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

		 // Allocate a buffer for the plaintext (this will be returned to the caller)

		 HBufC8* plaintextBuf = HBufC8::NewLC(decryptor->MaxFinalOutputLength(ciphertext->Length()));

		 TPtr8 plaintext = plaintextBuf->Des();

		 // Decrypt the data

		 decryptor->ProcessFinalL(*ciphertext, plaintext);

		 // Free memory (readStream, encryptionData, encryption, decryptor, ciphertext, plaintext)

		 CleanupStack::Pop(plaintextBuf); // don't free this

		 CleanupStack::PopAndDestroy(5, &readStream);

		 CleanupStack::PushL(plaintextBuf);

		 // Return plaintext to the caller

		 return plaintextBuf;

		 }

@endcode

*/