The case of the 9 bit AES key
v12.sh"MuPDF versions before 1.28.5 use an implementation of the drand48 family" yeah, ok, so they're basically not doing real encryption. The number of bits in the key space isn't the real story; the keys simply aren't cryptographically random.
Rule #1 of rolling your own RNG: don’t.
Rule #2? Please don’t.
That's why we use the system RNG !
Wonderful.
it's like the weak hardware wallet entropy bug
You'd have to be completely off your rocker to use a PDF tool written in C anyway.
very VERY few people judge tools like this by the language used to develop them.
How many people judge their tools based on the AES key entropy?
A lot actually.
You're confusing just assuming by default its enough for purpose rather than not caring at all.
What are the alternatives?
Genuine question, since I'm not very knowledgeable about this: why is using C for a PDF tool such a bad idea?
I think the claim is hyperbolic, since most people memory-unsafe PDF implementations, but PDF is a monster format, a metaformat that brings in virtually every conceivable display format, and their renderer implementations with them, often poorly-maintained, never-touched reference implementations from the before times. PDF is pretty scary.
buffer overflow vulnerability in code dealing with user generated data and a complex file format.