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Encryption settings dialog, authorization as owner

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Jakub Melka
2021-05-24 19:29:02 +02:00
parent 759d5c7793
commit 936fe2fbe7
9 changed files with 342 additions and 27 deletions
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61
Pdf4QtLib/sources/pdfsecurityhandler.h
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@ -109,6 +109,9 @@ public:
/// Retrieve encryption mode (none/standard encryption/custom)
virtual EncryptionMode getMode() const = 0;
/// Creates a clone of this object
virtual PDFSecurityHandler* clone() const = 0;
/// Performs authentication of the document content access. First, algorithm should check,
/// if empty password allows document access (so, for example, only owner password is provided).
/// If this fails, function \p getPasswordCallback is called to retrieve user entered password.
@ -214,6 +217,7 @@ class PDFNoneSecurityHandler : public PDFSecurityHandler
{
public:
virtual EncryptionMode getMode() const override { return EncryptionMode::None; }
virtual PDFSecurityHandler* clone() const override { return new PDFNoneSecurityHandler(); }
virtual AuthorizationResult authenticate(const std::function<QString(bool*)>&, bool) override { return AuthorizationResult::OwnerAuthorized; }
virtual QByteArray decrypt(const QByteArray& data, PDFObjectReference, EncryptionScope) const override { return data; }
virtual QByteArray decryptByFilter(const QByteArray& data, const QByteArray&, PDFObjectReference) const override { return data; }
@ -231,6 +235,7 @@ class PDFStandardSecurityHandler : public PDFSecurityHandler
{
public:
virtual EncryptionMode getMode() const override { return EncryptionMode::Standard; }
virtual PDFSecurityHandler* clone() const override;
virtual AuthorizationResult authenticate(const std::function<QString(bool*)>& getPasswordCallback, bool authorizeOwnerOnly) override;
virtual QByteArray decrypt(const QByteArray& data, PDFObjectReference reference, EncryptionScope encryptionScope) const override;
virtual QByteArray decryptByFilter(const QByteArray& data, const QByteArray& filterName, PDFObjectReference reference) const override;
@ -249,6 +254,9 @@ public:
QByteArray fileEncryptionKey;
};
/// Adjusts the password according to the PDF specification
static QByteArray adjustPassword(const QString& password, int revision);
private:
friend PDFSecurityHandlerPointer PDFSecurityHandler::createSecurityHandler(const PDFObject& encryptionDictionaryObject, const QByteArray& id);
@ -288,8 +296,6 @@ private:
/// Parses parts of the user/owner data (U/O values of the encryption dictionary)
UserOwnerData_r6 parseParts(const QByteArray& data) const;
/// Adjusts the password according to the PDF specification
QByteArray adjustPassword(const QString& password);
/// Decrypts data using specified filter. This function can be called only, if authorization was successfull.
/// \param data Data to be decrypted
@ -356,6 +362,57 @@ private:
AuthorizationData m_authorizationData;
};
/// Factory, which creates security handler based on settings.
class Pdf4QtLIBSHARED_EXPORT PDFSecurityHandlerFactory
{
public:
enum Algorithm
{
None,
RC4,
AES_128,
AES_256
};
enum EncryptContents
{
All,
AllExceptMetadata,
EmbeddedFiles
};
struct SecuritySettings
{
Algorithm algorithm = None;
EncryptContents encryptContents = All;
QString userPassword;
QString ownerPassword;
uint32_t permissions = 0;
};
/// Creates security handler based on given settings. If security handler cannot
/// be created, then nullptr is returned.
/// \param settings Security handler settings
static PDFSecurityHandlerPointer createSecurityHandler(const SecuritySettings& settings);
/// Returns optimal number of bits (entropy) for strong password
static int getPasswordOptimalEntropy();
/// Calculates password entropy (number of bits), can be used
/// for ranking the password security. Encryption algorithm must be also
/// considered, because password is adjusted according to the specification
/// before it's entropy is being computed.
/// \param password Password to be scored
/// \param algorithm Encryption algorithm
static int getPasswordEntropy(const QString& password, Algorithm algorithm);
/// Returns revision number of standard security handler for a given
/// algorithm. If algorithm is invalid or None, zero is returned.
/// \param algorithm Algorithm
static int getRevisionFromAlgorithm(Algorithm algorithm);
};
} // namespace pdf