此版更新內容

  • [Feature] 圖像數位簽章支援與驗證 (SIGNATURENET‑5528)
    引入基於隱寫術的數位簽章嵌入至 PNG 與 JPG 圖像。支援受密碼保護的簽章、串流/檔案處理，以及可選的偵測門檻的完整驗證。

  • [Enhancement] 簽章作業的 LINQ 查詢最佳化 (SIGNATURENET‑5500)
    重構整個函式庫的 LINQ 邏輯，以降低記憶體分配並提升執行速度。為 Search 與 Verify 方法加入基於條件式的過濾，使開發者能在耗時的處理前先行篩選簽章。

修正與增強

  • [Bug Fix] 修復在 Linux 上使用 DOC 格式時 GeneratePreview() 型別初始化例外的問題 (SIGNATURENET‑5555)
    現在在 Linux 環境中為 Microsoft Word 文件產生預覽時不再拋出例外。

如何使用新功能

對圖像簽章（隱寫術）

using GroupDocs.Signature;
using GroupDocs.Signature.Options;

string inputFile  = "image.png";
string outputFile = "signed_image.png";
string password   = "MySecurePassword123";

using (Signature signature = new Signature(inputFile))
{
    ImageDigitalSignOptions signOptions = new ImageDigitalSignOptions
    {
        Password = password
    };

    SignResult signResult = signature.Sign(outputFile, signOptions);

    if (signResult.Succeeded?.Count > 0)
    {
        Console.WriteLine("Image signed successfully!");
        Console.WriteLine($"Signatures added: {signResult.Succeeded.Count}");
    }
}

驗證已簽章的圖像

using GroupDocs.Signature;
using GroupDocs.Signature.Options;

string signedFile = "signed_image.png";
string password   = "MySecurePassword123";

using (Signature signature = new Signature(signedFile))
{
    ImageDigitalVerifyOptions verifyOptions = new ImageDigitalVerifyOptions
    {
        Password = password,
        DetectionThresholdPercent = 75   // optional, 0‑100%
    };

    VerificationResult verifyResult = signature.Verify(verifyOptions);

    if (verifyResult.IsValid)
    {
        Console.WriteLine("Digital signature is valid!");
        Console.WriteLine($"Verified signatures: {verifyResult.Succeeded.Count}");
    }
    else
    {
        Console.WriteLine("Digital signature is invalid or not found.");
    }
}

使用完整資料提取的進階驗證

using (Signature signature = new Signature("signed_image.png"))
{
    ImageDigitalVerifyOptions verifyOptions = new ImageDigitalVerifyOptions
    {
        Password = "MySecurePassword123",
        UseFullDataExtraction = true,          // maximum accuracy
        DetectionThresholdPercent = 85
    };

    VerificationResult verifyResult = signature.Verify(verifyOptions);

    if (verifyResult.IsValid && verifyOptions.DetectedProbability.HasValue)
    {
        Console.WriteLine($"Signature detected with {verifyOptions.DetectedProbability.Value}% probability");
    }
}

使用條件式的 LINQ 最佳化搜尋

using GroupDocs.Signature;
using GroupDocs.Signature.Options;
using GroupDocs.Signature.Domain;

using (Signature signature = new Signature("document.pdf"))
{
    List<SearchOptions> searchOptions = new List<SearchOptions>
    {
        new TextSearchOptions()
    };

    // Filter only text signatures containing "Approved"
    SearchResult result = signature.Search(searchOptions,
        sig => sig is TextSignature txt && txt.Text.Contains("Approved"));

    foreach (BaseSignature sig in result.Signatures)
    {
        Console.WriteLine($"Found: {((TextSignature)sig).Text}");
    }
}

使用條件式的 LINQ 最佳化驗證

using (Signature signature = new Signature("signed_document.pdf"))
{
    TextVerifyOptions verifyOptions = new TextVerifyOptions("John Smith");

    // Verify only signatures on page 1
    List<BaseSignature> result = signature.Verify(verifyOptions,
        sig => sig.PageNumber == 1);

    Console.WriteLine($"Found {result.Count} verified signatures on page 1");
}

如何取得更新

  • NuGet – 升級至最新的 GroupDocs.Signature 套件: 
    dotnet add package GroupDocs.Signature --version 25.12
  • Direct Download – 從官方發布頁面下載 .NET 的編譯組件:
    GroupDocs.Signature for .NET 25.12 DLLs

資源