Seamus E. Byrne's - In Pursuit of Relevance

Many software utilities are available to create Portable Document Format (PDF) documents and Adobe® Acrobat® is arguably the most popular utility for this purpose.

Adobe Acrobat 9

Adobe Acrobat 9 was announced this week.

With more redaction features than Acrobat 8, Adobe Acrobat 9 Professional supports pattern search redaction (e.g. automatic identification of e-mail addresses for redaction) and the automated redaction of words imported from a word list.

Defining Redaction

Redaction may be considered the process of permanently masking part of the contents of a document (e.g. a name, sentence or paragraph).

Redaction is generally undertaken to protect personal, irrelevant, sensitive, confidential or privileged information from future disclosure (whilst still distributing or producing the remainder of the document).

Redaction is distinct from the process of 'metadata removal' (also referred to as 'metadata scrubbing') – i.e. the process of permanently removing embedded information generally pertaining to the properties of a document.

Redaction - Why?

For example, as part of discovery, a lawyer may redact part of a discoverable document containing privileged information prior to exchange/production, effectively rendering the document 'part-privileged'.

See also: Wikipedia

Historical Perspective

Despite the introduction of built-in redaction features with Adobe Acrobat 8 Professional, mis-information is still prevalent in relation to PDF redaction. Such confusion has been intensified by continued media attention focused on data leakage from PDFs purportedly produced for discovery or made public as 'securely redacted'.

As the precursor to PDF, Tagged Image File Format (TIFF) images have traditionally been used for redaction. A number of litigation support systems also possess image viewing utilities able to mask out portions of text within a flattened (i.e. unsearchable, one-layer) image of a page.

Historically, PDF did not support the ability securely redact a portion of text. This limitation extends to the majority of PDFs in existence today, which are compliant to version 1.4 (Adobe Acrobat 5 or later) of the PDF specification.

Consequently, many individuals and organisations have experienced great embarrassment when an attempt to use 'black highlighting' or a 'black rectangle', as a second layer to a PDF, has led to the inadvertent leakage of confidential or sensitive information.

Moving Forward

In November 2006, Adobe released version 1.7 of the PDF specification (corresponding with Adobe Acrobat 8), which specifically addressed redaction.

Today, a user may open a PDF created with an earlier version of Adobe Acrobat (or an alternative PDF creation utility), and using Adobe Acrobat 8 Professional can securely redact selected text. Further, the built-in redaction utility automatically updates the PDF to version 1.7 and keeps the remainder of the searchable text within the document, searchable.

Acrobat Alternatives

Users without access (or budget) to the most recent versions of Adobe Acrobat Professional, may consider alternative software utilities, not limited to Appligent Redax or RapidRedact Desktop, to facilitate the efficient and secure redaction of PDFs.

Technical Reference

The PDF Reference provides technical documentation to facilitate the development of utilities to securely redact PDFs.

Update on July 2, 2008 by Seamus Byrne

PDF is now a formal international standard!

The Portable Document Format (PDF), undeniably one of the most commonly used formats for electronic documents, is now accessible as an ISO International Standard - ISO 32000-1. This move follows a decision by Adobe Systems Incorporated, original developer and copyright owner of the format, to relinquish control to ISO, who is now in charge of publishing the specifications for the current version (1.7) and for updating and developing future versions.