1 /**

     2 	@page secure_stream_example_code Secure stream example code

     3 	

     4 	This example covers: 

     5 	-# @ref stream_example_1 "Encrypting some data with a password and writing it to a file"

     6 	-# @ref stream_example_2 "Reading the data back from the file and decrypting it with the same password".

     7 

     8 	Also, see:

     9 	- @ref pbe_example_code

    10 	- @ref secure_store_example_code

    11 

    12 <hr>

    13 

    14 	@ref secure_stream_example_code_support "Supporting code for this example"

    15 

    16 @anchor stream_example_1

    17 @code

    18 /*

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

    20  */

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

    22 		 {

    23 		 // Open a stream to the output file

    24 		 RFileWriteStream writeStream;

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

    26 		 CleanupClosePushL(writeStream);

    27 

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

    29 		 // are using and the user's password

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

    31 

    32 		 // Store encryption data as the first thing in the stream

    33 		 writeStream << encryption->EncryptionData();

    34 

    35 		 // Create an REncryptStream - this wraps the write stream and encrypts

    36 		 // everything written to it

    37 		 REncryptStream encStream;

    38 		 encStream.OpenL(writeStream, *encryption);

    39 		 CleanupClosePushL(encStream);

    40 

    41 		 // Now we can simply write the plaintext to the encrypt stream - it gets

    42 		 // encrypted automatically

    43 		 encStream << aInput;

    44 

    45 		 // Commit the stream

    46 		 encStream.CommitL();

    47 

    48 		 // Free memory (writeStream, encryption, encStream)

    49 		 CleanupStack::PopAndDestroy(3, &writeStream);

    50 		 }

    51 @endcode

    52 

    53 @anchor stream_example_2

    54 @code

    55 /*

    56  * Read data from file and decrypt it.

    57  */

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

    59 		 {

    60 		 // Open a stream to the input file

    61 		 RFileReadStream readStream;

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

    63 		 CleanupClosePushL(readStream);

    64 

    65 		 // Read the encryption data from the stream

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

    67 		 

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

    69 		 // file and the user's password

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

    71 

    72 		 // Create an RDecryptStream based on the read stream - this decrypts

    73 		 // everything we read from it

    74 		 RDecryptStream decStream;

    75 		 decStream.OpenL(readStream, *encryption);

    76 		 CleanupClosePushL(decStream);

    77 

    78 		 // Now we can read the plaintext straight from the stream

    79 		 HBufC8* plaintext = HBufC8::NewL(decStream, KMaxTInt);

    80 		 

    81 		 // Free memory (readStream, encryptionData, encryption, decStream)

    82 		 CleanupStack::PopAndDestroy(4, &readStream);

    83 		 CleanupStack::PushL(plaintext);

    84 

    85 		 // Return plaintext to the caller

    86 		 return plaintext;

    87 		 }

    88 @endcode

    89 

    90 */