Welcome to the SecAware blog

I spy with my beady eye ...

23 Oct 2007

Yet another redaction failure

... this time it reveals the face of a man accused of sexually abusing boys in Vietnam and Cambodia. Photos of the man were redacted using a swirly filter effect that police somehow reversed. The resulting image is clearer than most CCTV snaps we see on TV crime watch programs.

Presumably the same kind of techniques would work on similarly redacted digital photos of vehicle license plates, associates of criminals and so forth. Provided there is sufficient original data in the redacted image, and provided the manipulation can be reversed without too much data loss, it's feasible.

Stories about un-redacting documents by cutting-and-pasting the original words from 'beneath' black boxes crudely added to PDFs etc. are simply passé.

The take home lesson for today is this: if something needs to be redacted, do it properly by removing, not just manipulating or covering the original data. There's a lot to be said for the 'print out -> obliterate with marker pen -> scan -> load' method.

UPDATE: a man has been arrested in Bangkok following release of the unredacted photo.

No comments:

Post a Comment