文件加密工具

使用 HTML5、CSS3 和 JavaScript，结合 Web Crypto API 创建一个客户端文件加密工具。构建一个支持拖放的文件选择界面，并带有进度指示器。实现 AES-256-GCM 加密，并通过 PBKDF2 从密码安全派生密钥。添加对同时加密多个文件的支持，并具备批处理能力。包含密码强度强制要求，并带熵值计算。生成可下载的加密文件，并使用自定义文件扩展名。创建一个带密码验证的解密界面。实现安全的内存处理，自动清除敏感数据。添加加密操作的详细日志，但不存储敏感信息。包含加密密钥的导出/导入功能，并提供适当的安全警告。通过流式加密和分块处理支持大文件。

Create a client-side file encryption tool using HTML5, CSS3, and JavaScript with the Web Crypto API. Build a drag-and-drop interface for file selection with progress indicators. Implement AES-256-GCM encryption with secure key derivation from passwords (PBKDF2). Add support for encrypting multiple files simultaneously with batch processing. Include password strength enforcement with entropy calculation. Generate downloadable encrypted files with custom file extension. Create a decryption interface with password verification. Implement secure memory handling with automatic clearing of sensitive data. Add detailed logs of encryption operations without storing sensitive information. Include export/import of encryption keys with proper security warnings. Support for large files using streaming encryption and chunked processing.