https://arxiv.org/pdf/2206.02285 https://arxiv.org/pdf/2206.02285 In this work we find that many current redactions of PDF text are insecure due to non-red

https://arxiv.org/pdf/2206.02285 https://arxiv.org/pdf/2206.02285 In this work we find that many current redactions of PDF text are insecure due to non-redacted character positioning information. In particular, subpixel-sized horizontal shifts in redacted and non-redacted characters can be recovered and used to effectively deredact first and last names. Information-theoretic attacks work on black boxes too