What's even more amazing is that it wasn't retracted from the PDF standard.
Everyone knew how dangerous it was, changing digits, but it was left in the standard and in many implementations.
Years and years later, someone implements a turing machine using it, hacks journalist's iPhones, and the question is: why did modern systems implement it?
Just searched for some details, it's amazing, all this inside of a JBIG2 image:
"Using over 70,000 segment commands defining logical bit operations, they define a small computer architecture with features such as registers and a full 64-bit adder and comparator which they use to search memory and perform arithmetic operations."
> changing digits, but it was left in the standard and in many implementations.
The format has a lossless mode that would have saved Xerox a lot of trouble, of course it was just that mode that was used to hack the iPhones.
Also for many texts you don't need every digit to be correct, hell any single typo, smudge or bad font can fuck you over if that is the case, no need for a Xerox. Ideally your numbers either include a checksum or have some other redundancy, like requiring that they are written out as words.
Everyone knew how dangerous it was, changing digits, but it was left in the standard and in many implementations.
Years and years later, someone implements a turing machine using it, hacks journalist's iPhones, and the question is: why did modern systems implement it?