Don't use text pixelation to redact sensitive information (bishopfox.com)

Article summary

The article discusses the insecurity of using pixelation to redact sensitive information in digital documents. A tool called Unredacter can reverse pixelated text back into its unredacted form, demonstrating the vulnerability of this method. The article highlights the importance of using secure redaction methods, such as black bars, to protect sensitive information. The Unredacter tool was used to solve a challenge posed by Jumpsec, which involved unredacting a pixelated image.

Main themes

• secure redaction methods
• pixelation vulnerability
• information leakage
• document security
• PDF and image compression
• metadata leakage
• redaction best practices

What commenters say

• Some commenters recommend printing and scanning documents as a way to securely redact information, while others suggest using software tools to convert PDFs to raster graphics.
• The use of pixelation or other insecure redaction methods can lead to sensitive information being leaked.
• Even using black bars to redact text may not be enough to prevent information leakage, especially if the image is compressed using JPEG.
• Some argue that saving edited documents to PNG before converting to JPEG may help prevent information leakage, but others disagree.
• The importance of understanding how PDFs and image compression work is emphasized in order to securely redact information.
• The need for secure redaction methods is highlighted, particularly when working with sensitive information such as personally identifiable information.
• Different methods of redaction, including digital replacement and overlay, are discussed, with some arguing that digital replacement is more secure.
• The potential for metadata leakage from printers and scanners is also noted as a concern.