NCryptUnprotectSecret function

The NCryptUnprotectSecret function decrypts data to a specified protection descriptor. Call NCryptProtectSecret to encrypt the data.

Syntax

NTSTATUS WINAPI NCryptUnprotectSecret(
  _Out_opt_ NCRYPT_DESCRIPTOR_HANDLE *phDescriptor,
  _In_      DWORD                    dwFlags,
  _In_      const BYTE               *pbProtectedBlob,
            ULONG                    cbProtectedBlob,
  _In_opt_  const NCRYPT_ALLOC_PARA  *pMemPara,
  _In_opt_  HWND                     hWnd,
  _Out_     BYTE                     **ppbData,
  _Out_     ULONG                    *pcbData
);

Parameters

phDescriptor [out, optional]

Pointer to the protection descriptor handle.

dwFlags [in]

The flag can be zero or a bitwise OR of the following values.

Value	Meaning
NCRYPT_SILENT_FLAG	Requests that the key service provider not display a user interface.
NCRYPT_UNPROTECT_NO_DECRYPT	Decodes only the header of the protected data blob. No actual decryption takes place.

 

pbProtectedBlob [in]

Pointer to an array of bytes that contains the data to decrypt.

cbProtectedBlob

The number of bytes in the array pointed to by the pbProtectedBlob parameter.

pMemPara [in, optional]

Pointer to an NCRYPT_ALLOC_PARA structure that you can use to specify custom memory management functions. If you set this argument to NULL, the LocalAlloc function is used internally to allocate memory and your application must call LocalFree to release memory pointed to by the ppbData parameter.

hWnd [in, optional]

Handle to the parent window of the user interface, if any, to be displayed.

ppbData [out]

Address of a variable that receives a pointer to the decrypted data.

pcbData [out]

Pointer to a ULONG variable that contains the size, in bytes, of the decrypted data pointed to by the ppbData variable.

Return value

Returns a status code that indicates the success or failure of the function. Possible return codes include, but are not limited to, the following.

Remarks

Use the NCryptUnprotectSecret function to decrypt keys, key material, and passwords. Use the NCryptStreamOpenToUnprotect and the NCryptStreamUpdate functions to decrypt larger messages.

Requirements

See also

CNG DPAPI Functions

NCryptProtectSecret