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Handling of encrypted documents - basic functionality for standard encryption handler revision 2,3,4

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Jakub Melka
2019-08-10 17:24:12 +02:00
parent 0a6e7bb866
commit 0434a70de5
5 changed files with 455 additions and 9 deletions
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74
PdfForQtLib/sources/pdfsecurityhandler.h
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@ -25,6 +25,7 @@
#include <QSharedPointer>
#include <map>
#include <functional>
namespace pdf
{
@ -73,14 +74,24 @@ public:
explicit PDFSecurityHandler() = default;
virtual ~PDFSecurityHandler() = default;
enum class AuthorizationResult
{
UserAuthorized,
OwnerAuthorized,
Failed,
Cancelled
};
virtual EncryptionMode getMode() const = 0;
virtual AuthorizationResult authenticate(const std::function<QString(bool*)>& getPasswordCallback) = 0;
/// Creates a security handler from the object. If object is null, then
/// "None" security handler is created. If error occurs, then exception is thrown.
/// \param encryptionDictionaryObject Encryption dictionary object
static PDFSecurityHandlerPointer createSecurityHandler(const PDFObject& encryptionDictionaryObject);
/// \param id First part of the id of the document
static PDFSecurityHandlerPointer createSecurityHandler(const PDFObject& encryptionDictionaryObject, const QByteArray& id);
private:
protected:
/// Version of the encryption, shall be a number from 1 to 5, according the
/// PDF specification. Other values are invalid.
int m_V = 0;
@ -107,6 +118,7 @@ class PDFNoneSecurityHandler : public PDFSecurityHandler
{
public:
virtual EncryptionMode getMode() const { return EncryptionMode::None; }
virtual AuthorizationResult authenticate(const std::function<QString(bool*)>&) override { return AuthorizationResult::OwnerAuthorized; }
};
/// Specifies the security using standard security handler (see PDF specification
@ -115,9 +127,67 @@ class PDFStandardSecurityHandler : public PDFSecurityHandler
{
public:
virtual EncryptionMode getMode() const { return EncryptionMode::Standard; }
virtual AuthorizationResult authenticate(const std::function<QString(bool*)>& getPasswordCallback) override;
struct AuthorizationData
{
};
private:
friend static PDFSecurityHandlerPointer PDFSecurityHandler::createSecurityHandler(const PDFObject& encryptionDictionaryObject, const QByteArray& id);
/// Creates file encryption key from passed password, based on the revision
/// \param password Password to be used to create file encryption key
/// \note Password must be in PDFDocEncoding for revision 4 or earlier,
/// otherwise it must be encoded in UTF-8.
QByteArray createFileEncryptionKey(const QByteArray& password) const;
/// Creates entry value U based on the file encryption key. This function
/// is valid only for revisions 2, 3 and 4.
/// \param fileEncryptionKey File encryption key
QByteArray createEntryValueU_r234(const QByteArray& fileEncryptionKey) const;
/// Creates user password from the owner password. User password must be then
/// authenticated.
QByteArray createUserPasswordFromOwnerPassword(const QByteArray& password) const;
/// Creates 32-byte padded password from the passed password. If password is empty,
/// then padding password is returned.
std::array<uint8_t, 32> createPaddedPassword32(const QByteArray& password) const;
/// Revision number of standard security number
int m_R = 0;
/// 32 byte string if revision number is 4 or less, or 48 byte string,
/// if revision number is 6, based on both owner and user passwords,
/// used for authenticate owner, and create a file encryption key.
QByteArray m_O;
/// 32 byte string if revision number is 4 or less, or 48 byte string,
/// if revision number is 6, based on both owner and user passwords,
/// used for authenticate owner, and create a file encryption key.
QByteArray m_U;
/// For revision number 6 only. 32 bytes string based on both owner
/// and user password, that shall be used to compute file encryption key.
QByteArray m_OE;
/// For revision number 6 only. 32 bytes string based on both owner
/// and user password, that shall be used to compute file encryption key.
QByteArray m_UE;
/// What operations shall be permitted, when document is opened with user access.
uint32_t m_permissions = 0;
/// For revision number 6 only. 16 byte encrypted version of permissions.
QByteArray m_Perms;
/// Optional, meaningfull only if revision number is 4 or 5.
bool m_encryptMetadata = true;
/// First part of the id of the document
QByteArray m_ID;
};
} // namespace pdf