Redact Information in PDF

Redact Information in PDF using C#

GroupDocs.Redaction(which is a part of Conholdate.Total for .NET) allows developers to redact information in PDF Documents.

With GroupDocs.Redaction API you can do text redaction using exact phrase or regular expression for your PDF documents.

Use exact phrase redaction

The example below shows textual redaction, replacing personal exact phrase “John Doe” with “[personal]” (or any exemption code):

C#

using (Redactor redactor = new Redactor(@"sample.pdf"))
{
  redactor.Apply(new ExactPhraseRedaction("John Doe", new ReplacementOptions("[personal]")));
  redactor.Save();
}

By default, search for exact phase is case insensitive.For a case-sensitive redaction, there is a constructor parameter and corresponding public property:

C#

using (Redactor redactor = new Redactor(@"sample.pdf"))
{
  redactor.Apply(new ExactPhraseRedaction("John Doe", true /*isCaseSensitive*/, new ReplacementOptions("[personal]")));
  redactor.Save();
}

If you need a color box over the redacted text, you can use color instead of replacement string. The redaction will erase matched text and put a rectangle of the specified color in place of redacted text:

C#

using (Redactor redactor = new Redactor(@"sample.pdf"))
{
  redactor.Apply(new ExactPhraseRedaction("John Doe", new ReplacementOptions(System.Drawing.Color.Black)));
  redactor.Save();
}

Use regular expression

Behind the scenes, “exact phrase” redaction works though regular expressions, which are the baseline approach for redaction. In the example below, we redact out any text, matching “2 digits, space or nothing, 2 digits, again space and 6 digits” with a blue color box:

C#

using (Redactor redactor = new Redactor(@"sample.pdf"))
{
  redactor.Apply(new RegexRedaction("\\d{2}\\s*\\d{2}[^\\d]*\\d{6}", new ReplacementOptions(System.Drawing.Color.Blue)));
  redactor.Save();
}