PdfiumFPDF_GetEncryptDictionary Method

public static IntPtr FPDF_GetEncryptDictionary(
	IntPtr document
)

Public Shared Function FPDF_GetEncryptDictionary ( 
	document As IntPtr
) As IntPtr

public:
static IntPtr FPDF_GetEncryptDictionary(
	IntPtr document
)

static member FPDF_GetEncryptDictionary : 
        document : IntPtr -> IntPtr 

public static IntPtr FPDF_GetEncryptDictionary(
	IntPtr document
)

Patagames.Pdf.Pdfium.FPDF_GetEncryptDictionary = function(document);

Parameters

document  IntPtr

Handle to document. Returned by FPDF_LoadDocument(String, String) function.

Return Value

Note
When a PDF stream object refers to an external file, the stream’s contents are not encrypted, since they are not part of the PDF file itself. However, if the contents of the stream are embedded within the PDF file, they are encrypted like any other stream in the file. Beginning with PDF 1.5, embedded files may be encrypted in an otherwise unencrypted document.

Encryption-related information is stored in a document’s encryption dictionary, which is the value of the Encrypt entry in the document’s trailer dictionary. The absence of this entry from the trailer dictionary means that the document is not encrypted.

The encryption dictionary’s Filter entry identifies the file’s security handler, a software module that implements various aspects of the encryption process and controls access to the contents of the encrypted document. PDF specifies a standard password-based security handler that all consumer applications are expected to support, but applications may optionally provide security handlers of their own.

The SubFilter entry specifies the syntax of the encryption dictionary contents. It allows interoperability between handlers; that is, a document may be decrypted by a handler other than the preferred one (the Filter entry) if they both support the format specified by SubFilter.

The V entry, in specifying which algorithm to use, determines the length of the encryption key, on which the encryption(and decryption) of data in a PDF file is based.For V values 2 and 3, the Length entry specifies the exact length of the encryption key. In PDF 1.5, a value of 4 for V permits the security handler to use its own encryption and decryption algorithms and to specify crypt filters to use on specific streams.

Reference