How to properly redact a PDF?

Hello, 

Using black rectangles is not considered a secure way to redact a PDF because the underlying content may still be present and recoverable.

The safest approach is to use a dedicated PDF redaction feature that permanently removes the selected content rather than simply hiding it. (as Adobe Acrobat) 

In addition to redacting the visible content, I would also recommend removing hidden information such as comments, document properties, metadata, attachments, form fields, and other embedded content before sharing the file.

Before sending the document, verify that the redacted content is no longer searchable, selectable, or copyable, and review the document properties to confirm that no sensitive metadata remains.

For highly sensitive documents, some organizations also choose to create a new PDF from the redacted output as an additional safeguard.

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