PdfSignerDocTimeStamp.h

// SPDX-FileCopyrightText: 2026 Francesco Pretto <ceztko@gmail.com>
// SPDX-License-Identifier: LGPL-2.0-or-later OR MPL-2.0
 
#ifndef PDF_SIGNER_DOC_TIMESTAMP_H
#define PDF_SIGNER_DOC_TIMESTAMP_H
 
#include "PdfSigner.h"
 
extern "C"
{
    // OpenSSL forward declaration
    struct evp_md_ctx_st;
    // libxml2 forward declaration
    typedef struct _xmlNode xmlNode;
    typedef xmlNode* xmlNodePtr;
}
 
namespace PoDoFo
{
    using PdfTimeStampService = std::function<void(bufferview hash, bool dryrun, charbuff& timeStamp)>;
 
    enum class PdfSignerDocTimeStampFlags : uint32_t
    {
        None = 0,
        SkipVerification = 1,
    };
 
    struct PODOFO_API PdfSignerDocTimeStampParams final
    {
        PdfHashingAlgorithm Hashing = PdfHashingAlgorithm::SHA256;
        PdfTimeStampService TimeStampService;
        unsigned ReservedSize = 0;
        PdfSignerDocTimeStampFlags Flags = PdfSignerDocTimeStampFlags::None;
    };
 
    class PODOFO_API PdfSignerDocTimeStamp : public PdfSigner
    {
        friend class PdfSigningContext;
    public:
        static constexpr unsigned DefaultReservedSize = 8192;
 
    public:
        PdfSignerDocTimeStamp(const PdfSignerDocTimeStampParams& parameters = { });
 
        ~PdfSignerDocTimeStamp();
 
    public:
        void Reset() override;
        void AppendData(const bufferview& data) override;
        void ComputeSignature(charbuff& contents, bool dryrun) override;
        void FetchIntermediateResult(charbuff& result) override;
        void ComputeSignatureDeferred(const bufferview& processedResult, charbuff& contents, bool dryrun) override;
        std::string GetSignatureSubFilter() const override;
        std::string GetSignatureType() const override;
 
    public:
        const PdfSignerDocTimeStampParams& GetParameters() const { return m_parameters; }
 
    private:
        // Called by PdfSigningContext
        void Dump(xmlNodePtr signerElem, std::string& temp);
        void Restore(xmlNodePtr signerElem, charbuff& temp);
    private:
        void ensureEventBasedTimestamping();
        void ensureDeferredTimestamping();
        void ensureDigestInitialized();
        void resetDigest();
        void ensureHashComputed();
        void setContents(const bufferview& timeStamp, charbuff& contents);
        bool shouldVerify() const;
    private:
        nullable<bool> m_deferredTimestamping;
        PdfSignerDocTimeStampParams m_parameters;
        struct evp_md_ctx_st* m_digestCtx;
        // The document digest, empty until computed
        charbuff m_hash;
 
        // Temporary buffer variables
        // NOTE: Don't clear it in Reset() override
        charbuff m_timeStamp;
    };
}
 
ENABLE_BITMASK_OPERATORS(PoDoFo::PdfSignerDocTimeStampFlags);
 
#endif // PDF_SIGNER_DOC_TIMESTAMP_H