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A malicious "redacting" algorithm submitted to the underhanded C contest used a similar idea, just on lower level. PNG allows ASCII numbers, so flipping all di
by praptak 5y ago
A malicious "redacting" algorithm submitted to the underhanded C contest used a similar idea, just on lower level.
PNG allows ASCII numbers, so flipping all digits to 0 creates a pixel which is graphically "masked" but leaks information about the original pixel: "000" means the value was larger than 99.
- anderskaseorg 5y agoThat’s PPM format, not PNG. http://underhanded-c.org/_page_id_17.html http://underhanded-c.org/_page_id_17.html http://netpbm.sourceforge.net/doc/ppm.html http://netpbm.sourceforge.net/doc/ppm.html