PDF4QT/PdfForQtLib/sources/pdfsignaturehandler.h
2020-06-14 18:40:42 +02:00

238 lines
9.5 KiB
C++

// Copyright (C) 2020 Jakub Melka
//
// This file is part of PdfForQt.
//
// PdfForQt is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// PdfForQt is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with PDFForQt. If not, see <https://www.gnu.org/licenses/>.
#ifndef PDFSIGNATUREHANDLER_H
#define PDFSIGNATUREHANDLER_H
#include "pdfglobal.h"
#include "pdfobject.h"
#include <optional>
namespace pdf
{
class PDFForm;
class PDFObjectStorage;
class PDFFormFieldSignature;
/// Signature reference dictionary.
class PDFSignatureReference
{
public:
enum class TransformMethod
{
Invalid,
DocMDP,
UR,
FieldMDP
};
TransformMethod getTransformMethod() const { return m_transformMethod; }
const PDFObject& getTransformParams() const { return m_transformParams; }
const PDFObject& getData() const { return m_data; }
const QByteArray& getDigestMethod() const { return m_digestMethod; }
/// Tries to parse the signature reference. No exception is thrown, in case of error,
/// invalid signature reference object is returned.
/// \param storage Object storage
/// \param object Object containing the signature
static PDFSignatureReference parse(const PDFObjectStorage* storage, PDFObject object);
private:
TransformMethod m_transformMethod = TransformMethod::Invalid;
PDFObject m_transformParams;
PDFObject m_data;
QByteArray m_digestMethod;
};
/// Signature dictionary. Contains digital signature. This signature can be validated by signature validator.
/// This object contains certificates, digital signatures, and other information about signature.
class PDFSignature
{
public:
enum class Type
{
Invalid,
Sig,
DocTimeStamp
};
struct ByteRange
{
PDFInteger offset = 0;
PDFInteger size = 0;
};
using ByteRanges = std::vector<ByteRange>;
struct Changes
{
PDFInteger pagesAltered = 0;
PDFInteger fieldsAltered = 0;
PDFInteger fieldsFilled = 0;
};
enum class AuthentificationType
{
Invalid,
PIN,
Password,
Fingerprint
};
/// Tries to parse the signature. No exception is thrown, in case of error,
/// invalid signature object is returned.
/// \param storage Object storage
/// \param object Object containing the signature
static PDFSignature parse(const PDFObjectStorage* storage, PDFObject object);
Type getType() const { return m_type; }
const QByteArray& getFilter() const { return m_filter; }
const QByteArray& getSubfilter() const { return m_subfilter; }
const QByteArray& getContents() const { return m_contents; }
const std::vector<QByteArray>* getCertificates() const { return m_certificates.has_value() ? &m_certificates.value() : nullptr; }
const ByteRanges& getByteRanges() const { return m_byteRanges; }
const std::vector<PDFSignatureReference>& getReferences() const { return m_references; }
const Changes* getChanges() const { return m_changes.has_value() ? &m_changes.value() : nullptr; }
const QString& getName() const { return m_name; }
const QDateTime& getSigningDateTime() const { return m_signingDateTime; }
const QString& getLocation() const { return m_location; }
const QString& getReason() const { return m_reason; }
const QString& getContactInfo() const { return m_contactInfo; }
PDFInteger getR() const { return m_R; }
PDFInteger getV() const { return m_V; }
const PDFObject& getPropBuild() const { return m_propBuild; }
PDFInteger getPropTime() const { return m_propTime; }
AuthentificationType getAuthentificationType() const { return m_propType; }
private:
Type m_type = Type::Invalid;
QByteArray m_filter; ///< Preferred signature handler name
QByteArray m_subfilter; ///< Describes encoding of signature
QByteArray m_contents;
std::optional<std::vector<QByteArray>> m_certificates; ///< Certificate chain (only for adbe.x509.rsa_sha1)
ByteRanges m_byteRanges;
std::vector<PDFSignatureReference> m_references;
std::optional<Changes> m_changes;
QString m_name; ///< Name of signer. Should rather be extracted from signature.
QDateTime m_signingDateTime; ///< Signing date and time. Should be extracted from signature, if possible.
QString m_location; ///< CPU hostname or physical location of signing
QString m_reason; ///< Reason for signing
QString m_contactInfo; ///< Contact info for verifying the signature
PDFInteger m_R; ///< Version of signature handler. Obsolete.
PDFInteger m_V; ///< Version of signature dictionary format. 1 if References should be used.
PDFObject m_propBuild;
PDFInteger m_propTime = 0;
AuthentificationType m_propType = AuthentificationType::Invalid;
};
class PDFFORQTLIBSHARED_EXPORT PDFSignatureVerificationResult
{
public:
explicit PDFSignatureVerificationResult() = default;
explicit PDFSignatureVerificationResult(PDFObjectReference signatureFieldReference, QString qualifiedName) :
m_signatureFieldReference(signatureFieldReference),
m_signatureFieldQualifiedName(qualifiedName)
{
}
enum VerificationFlag
{
None = 0x00000, ///< Used only for initialization
OK = 0x00001, ///< Both certificate and signature is OK
Error_NoHandler = 0x00002, ///< No signature handler for given signature
Error_Generic = 0x00004, ///< Generic error (uknown general error)
Error_Certificate_Invalid = 0x00008, ///< Certificate is invalid
Error_Certificate_NoSignatures = 0x00010, ///< No signature found in certificate data
Error_Certificate_Missing = 0x00020, ///< Certificate is missing
Error_Certificate_Generic = 0x00040, ///< Generic error during certificate verification
Error_Certificate_Expired = 0x00080, ///< Certificate has expired
Error_Certificate_SelfSigned = 0x00100, ///< Self signed certificate
Error_Certificate_SelfSignedChain = 0x00200, ///< Self signed certificate in chain
Error_Certificate_TrustedNotFound = 0x00400, ///< No trusted certificate was found
Error_Certificate_Revoked = 0x00800, ///< Certificate has been revoked
Error_Certificate_Other = 0x01000, ///< Other certificate error. See OpenSSL code for details.
};
Q_DECLARE_FLAGS(VerificationFlags, VerificationFlag)
/// Adds no handler error for given signature format
/// \param format Signature format
void addNoHandlerError(const QByteArray& format);
void addInvalidCertificateError();
void addNoSignaturesError();
void addCertificateMissingError();
void addCertificateGenericError();
void addCertificateExpiredError();
void addCertificateSelfSignedError();
void addCertificateSelfSignedInChainError();
void addCertificateTrustedNotFoundError();
void addCertificateRevokedError();
void addCertificateOtherError(int error);
bool isValid() const { return hasFlag(OK); }
bool hasError() const { return !isValid(); }
bool hasFlag(VerificationFlag flag) const { return m_flags.testFlag(flag); }
PDFObjectReference getSignatureFieldReference() const { return m_signatureFieldReference; }
const QString& getSignatureFieldQualifiedName() const { return m_signatureFieldQualifiedName; }
const QStringList& getErrors() const { return m_errors; }
void setSignatureFieldQualifiedName(const QString& signatureFieldQualifiedName);
void setSignatureFieldReference(PDFObjectReference signatureFieldReference);
private:
VerificationFlags m_flags = None;
PDFObjectReference m_signatureFieldReference;
QString m_signatureFieldQualifiedName;
QStringList m_errors;
};
/// Signature handler. Can verify both certificate and signature validity.
class PDFFORQTLIBSHARED_EXPORT PDFSignatureHandler
{
public:
explicit PDFSignatureHandler() = default;
virtual ~PDFSignatureHandler() = default;
virtual PDFSignatureVerificationResult verify() const = 0;
/// Tries to verify all signatures in the form. If form is invalid, then
/// empty vector is returned.
/// \param form Form
/// \param sourceData Source data
static std::vector<PDFSignatureVerificationResult> verifySignatures(const PDFForm& form, const QByteArray& sourceData);
private:
/// Creates signature handler using format specified by signature in signature field.
/// If signature format is unknown, then nullptr is returned.
/// \param signatureField Signature field
/// \param sourceData
static PDFSignatureHandler* createHandler(const PDFFormFieldSignature* signatureField, const QByteArray& sourceData);
};
} // namespace pdf
#endif // PDFSIGNATUREHANDLER_H