Carry propagation bugs are something that can go wrong in a bignum implementation.
Bignum is what you need when you have one number that you're splitting between multiple variables (because it's a 256-bit number, and you want your library to work on 32-bit PCs, for example).
Carry propagation is if part of your result is too large for one part of your number and needs to overflow into the next part.
Bignum is what you need when you have one number that you're splitting between multiple variables (because it's a 256-bit number, and you want your library to work on 32-bit PCs, for example).
Carry propagation is if part of your result is too large for one part of your number and needs to overflow into the next part.
Actual carry propagation bug and bugfix available here: https://news.ycombinator.com/item?id=8857363