使用C++向已签名的Excel文件添加数字签名

可能的使用场景

Aspose.Cells提供Workbook::AddDigitalSignature(DigitalSignatureCollectionPtr digitalSignatureCollection)方法向已签名的Excel文件添加数字签名。

添加数字签名到已签名的Excel文档时的注意事项：如果原始文档由Aspose.Cells生成，则功能正常。但如果文档由其他引擎（如Microsoft Excel）创建，Aspose.Cells for C++无法在加载和重新保存后保持精确的文件结构，可能会使现有签名失效。

如何向已经签名的Excel文件添加数字签名

以下示例代码演示了如何使用 Workbook::AddDigitalSignature 在已签名的Excel文件中添加数字签名。示例Excel文件（50528280.xlsx）已预先签名。输出文件（50528281.xlsx）展示了效果。我们使用带密码的演示证书 AsposeDemo.pfx，密码为 aspose。

示例代码

#include <iostream>
#include "Aspose.Cells.h"
using namespace Aspose::Cells;
using namespace Aspose::Cells::DigitalSignatures;

int main()
{
    Aspose::Cells::Startup();

    // Source and output directories
    U16String srcDir(u"..\\Data\\01_SourceDirectory\\");
    U16String outDir(u"..\\Data\\02_OutputDirectory\\");

    // Certificate and workbook paths
    U16String certFilePath = srcDir + u"AsposeDemo.pfx";
    U16String inputFilePath = srcDir + u"sampleDigitallySignedByCells.xlsx";
    U16String outputFilePath = outDir + u"outputDigitallySignedByCells.xlsx";

    // Load digitally signed workbook
    Workbook workbook(inputFilePath);

    // Create digital signature collection
    DigitalSignatureCollection dsCollection;

    // Create digital signature using PFX certificate
    U16String password = u"aspose";
    U16String comments = u"Aspose.Cells added new digital signature in existing digitally signed workbook.";
    DigitalSignature signature(certFilePath, password, comments, Date());

    // Add signature to collection
    dsCollection.Add(signature);

    // Apply digital signatures to workbook
    workbook.AddDigitalSignature(dsCollection);

    // Save modified workbook
    workbook.Save(outputFilePath);

    std::cout << "Digital signature added successfully." << std::endl;

    Aspose::Cells::Cleanup();
    return 0;
}