PDFlibPas: Delphi での encryption and permissions audit

losLab PDF Library は、Delphi/C++Builder チーム向けにソース提供の PDF エンジンを提供します。デスクトップ、サーバー、DLL、ActiveX、Dylib ワークフローで使え、PDF/A・PDF/UA チェック、PAdES 署名、複数レンダラーを外部 PDF サービスなしで利用できます。

この記事は developers building document intake, governance, or support tools that need to explain PDF security state 向けです。encryption and permissions audit を単なるコンポーネント呼び出しではなく、本番向けのドキュメントエンジニアリングとして扱います。

実務上のリスクは operators may see a locked document icon but still not know which actions are permitted, which objects are encrypted, or whether policy allows processing です。そのため、明確な契約、観測可能な診断、実際の顧客ファイルに近い回帰サンプルが必要です。

アーキテクチャ上の判断

Report security state before acting on the file. which encrypted documents can be previewed, exported, printed, or routed / how password prompts, credential storage, and retry limits are handled

which encrypted documents can be previewed, exported, printed, or routed
how password prompts, credential storage, and retry limits are handled
whether metadata, attachments, and embedded files must be inspected separately
which permission combinations block automation or require manual approval

実装フロー

Convert encryption details into policy findings. The order below keeps the workflow reviewable for Delphi and C++Builder teams.

open the document through a controlled security-inspection path
read encryption details and normalize permissions into application policy names
inspect metadata and attachments according to the same security profile
present operator decisions as allow, warn, block, or request credentials
store a redacted security report with the intake or support record

検証エビデンス

Security audit fields that matter. Keep these fields with the output or support record.

algorithm, key length, owner password requirement, user password state, and metadata policy
permission flags mapped to print, copy, edit, annotate, extract, and form-fill outcomes
attachment and embedded-file security state
credential prompt result without storing password values

Permissions are not user-interface hints

A security audit should distinguish encryption algorithm, owner and user password requirements, permission flags, metadata handling, attachment state, and viewer behavior. The result should drive application policy rather than simply display raw bits.

サポートパッケージの設計

PDFlibPas を展開した後に最も役立つサポートパッケージは、入力、プロファイル、出力、そして失敗した正確な段階を説明するものです

algorithm, key length, owner password requirement, user password state, and metadata policy
permission flags mapped to print, copy, edit, annotate, extract, and form-fill outcomes
attachment and embedded-file security state
credential prompt result without storing password values
terminology snapshot: encryption, permission flags, metadata, attachments

encryption and permissions audit に関する技術レビューの注意点

これらのレビュー項目を使って、機能がデモ段階を超え、リリース、サポート、顧客エスカレーションの場で説明できることを確認します

判断: which encrypted documents can be previewed, exported, printed, or routed. 実装上の焦点: read encryption details and normalize permissions into application policy names. 受け入れ証拠: attachment and embedded-file security state. 回帰の引き金: support logs must never include passwords or derived secret material
判断: how password prompts, credential storage, and retry limits are handled. 実装上の焦点: inspect metadata and attachments according to the same security profile. 受け入れ証拠: credential prompt result without storing password values. 回帰の引き金: viewer permissions can be advisory and should not replace application policy
判断: whether metadata, attachments, and embedded files must be inspected separately. 実装上の焦点: present operator decisions as allow, warn, block, or request credentials. 受け入れ証拠: algorithm, key length, owner password requirement, user password state, and metadata policy. 回帰の引き金: encrypted metadata may prevent routing rules that depend on title or author
判断: which permission combinations block automation or require manual approval. 実装上の焦点: store a redacted security report with the intake or support record. 受け入れ証拠: permission flags mapped to print, copy, edit, annotate, extract, and form-fill outcomes. 回帰の引き金: attachments can carry sensitive data not visible on document pages
判断: which encrypted documents can be previewed, exported, printed, or routed. 実装上の焦点: open the document through a controlled security-inspection path. 受け入れ証拠: attachment and embedded-file security state. 回帰の引き金: support logs must never include passwords or derived secret material
判断: how password prompts, credential storage, and retry limits are handled. 実装上の焦点: read encryption details and normalize permissions into application policy names. 受け入れ証拠: credential prompt result without storing password values. 回帰の引き金: viewer permissions can be advisory and should not replace application policy

境界ケース

viewer permissions can be advisory and should not replace application policy
encrypted metadata may prevent routing rules that depend on title or author
attachments can carry sensitive data not visible on document pages
support logs must never include passwords or derived secret material

Delphi / C++Builder の補足

PDFlibPas should sit behind a small service boundary that receives files, streams, profiles, and credentials, then returns output paths, warnings, metrics, and validation status. 重要な用語には encryption, permission flags, metadata, attachments, owner password, audit report.

Delphi コード例

次の Delphi スケッチは、このテーマに対する実用的なサービス境界を示します。ポリシー確認、ログ記録、検証を製品呼び出しの狭い部分の外側に置くと、ワークフローをテストしやすくなります。

procedure AuditEncryptionPolicy(const InputFile, OutputFile: string; const Policy: TEncryptionPolicy);
var
  Pdf: TPDFlib;
begin
  Pdf := TPDFlib.Create;
  try
    Pdf.EncryptFile(InputFile, OutputFile, Policy.OwnerPassword, Policy.UserPassword,
      Policy.Strength, Policy.Permissions);
    WriteEncryptionAudit(OutputFile, Pdf.EncryptionAlgorithm, Policy.Permissions);
  finally
    Pdf.Free;
  end;
end;

本番チェックリスト

ワークフローは、空のファイル、通常の顧客ファイル、最悪ケースのファイルで実行します
生成された PDF は、対象のビューアー、検証ツール、プリンター、または downstream アプリケーションで開きます
製品バージョン、プロファイルバージョン、入力ハッシュ、出力パス、経過時間、警告数を記録します
パスワード、証明書、一時ファイル、顧客データは明確な保持ルールの下で管理します
顧客ファイルが新しい境界ケースを示したら、回帰用ドキュメントを追加します

製品ドキュメント

PDFlibPas

追加のコード例

var
  PDF: TPDFlib;
  R: Integer;
begin
  PDF := TPDFlib.Create;
  try
    R := PDF.EncryptFile('in.pdf', 'out.pdf', 'owner-secret', 'user-secret', 4,
      PDF.EncodePermissions(1, 0, 0, 0,    // print allowed; copy/change/notes denied
                            0, 0, 0, 1));  // extended set: full-quality print only
    if (R = 1) and (PDF.LoadFromFile('out.pdf', 'user-secret') = 1) then
    begin
      Writeln('algorithm = ', PDF.EncryptionAlgorithm);
      Writeln('strength  = ', PDF.EncryptionStrength);
      Writeln('owner pw accepted: ', PDF.CheckPassword('owner-secret'));
    end;
  finally
    PDF.Free;
  end;
end;

if not Doc.Encrypt('owner-secret', 'user-secret', esAES256BitAcroX,
  [ppCanPrint], [ppCanPrintFull]) then
  raise Exception.Create('Encryption failed');