Sorry if this has been answered before, but I just found out about YACoin and I don't want to read all 170 pages.
Is YACoin just continually raising the N value? Does this mean it will eventually take a huge amount of time to check a block PoW for validity? How could this possibly be a good idea?
Probably the YACoin ongoing development thread will give you a better idea while reading much less than 170 pages:
https://bitcointalk.org/index.php?topic=206577.0My post with my benchmarks for hash rates at various values of N, and when YACoin will switch to those values of N, is in the 15th post:
https://bitcointalk.org/index.php?topic=206577.msg2162620#msg2162620I benchmarked with a 4 year old dual Xeon E5450 server (almost stone age technology, but similar combined performance to today's i7-2600k's). It appears it'll be a few decades before even today's hardware (or hardware from 4 years ago) would have a problem with the time needed to validate a block PoW.
As time goes on, doubling of N becomes further and further apart in time. Advances in computing power will rapidly outpace the rising N over the long term.