Reminds me of my favourite winner of the underhanded c contest, back in 2008 http://notanumber.net/archives/54/underhanded-c-the-leaky-redaction http://notanumb

Reminds me of my favourite winner of the underhanded c contest, back in 2008 http://notanumber.net/archives/54/underhanded-c-the-leaky-redaction http://notanumber.net/archives/54/underhanded-c-the-leaky-re... Effectively this draws 'black boxes', but in a way that allows the developer to recover much information from the document if desired. The trick is in the ppm format, where a 0, 00, and 000 are all valid 'black' values. The redaction works by turning all 'digits' into zeros in the specified area ... but obviously you can recover much information by turning those zeros back into full values. In the case of black-on-white text, this effectively recovers the text completely. Brilliant!