Unprotect Method

Unprotects the data.

Syntax

• C++
• Objective-C
• C

ANSI (Cross Platform)
int Unprotect();

Unicode (Windows)
INT Unprotect();

- (void)unprotect;

#define MID_DPAPI_UNPROTECT 7

IPWORKSENCRYPT_EXTERNAL int IPWORKSENCRYPT_CALL IPWorksEncrypt_DPAPI_Do(void *lpObj, int methid, int cparam, void *param[], int cbparam[], int64 *lpllVal);

Remarks

Unprotect unprotects the specified data.

The class supports unprotecting data using either the classic DPAPI or CNG DPAPI implementation. The use of UseCNG determines which implementation is used. The list of applicable properties differs depending on whether CNG DPAPI is being used.

When using classic DPAPI (UseCNG is False), the following optional properties are applicable:

• DataDescription (populated after completion)
• Password

When using CNG DPAPI (UseCNG is True), the following properties are applicable:

• ProtectionDescriptor (populated after completion)
• UseStreamMode

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Code Example (Classic DPAPI - UseCNG is False)

//Protect
Dpapi dpapi = new Dpapi();
dpapi.InputMessage = "test";
dpapi.Protect();
byte[] protectedData = dpapi.OutputMessageB;

//Unprotect
dpapi = new Dpapi();
dpapi.InputMessageB = protectedData;
dpapi.Unprotect();
Console.WriteLine(dpapi.OutputMessage); //outputs "test"

Code Example (CNG DPAPI - UseCNG is True)

//Protect
Dpapi dpapi = new Dpapi();
dpapi.UseCNG = true;
dpapi.ProtectionDescriptor = "LOCAL=user";
dpapi.InputMessage = "test";
dpapi.Protect();
byte[] protectedData = dpapi.OutputMessageB;

//Unprotect
dpapi = new Dpapi();
dpapi.UseCNG = true;
dpapi.InputMessageB = protectedData;
dpapi.Unprotect();
Console.WriteLine(dpapi.OutputMessage); //outputs "test"

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)