Unlike hashing (basically, math), I don't see how input output or free space can't be faked. How do you know that your hard drive has free space? Because your firmware says it's a 1TB drive and you only have 500GB available. If you alter the firmware to show a different number of cylinders/sectors then you can magically create a 10TB drive or a 100TB drive.
The same can be done for input/output responses from storage drivers. I can create a fake compressed drive stored in memory and do 1M IOPS and there wouldn't be an easy way of detecting it.
In short, I'm not saying that it's not possible, but I think it's much harder to prove that a transaction really took place on a storage space or networking device than is simple hashing math, aka hashcash.
Heh, don't get me wrong, I'm only just beginning to look into the possibilities of PoC. As I've already alluded to after looking at numerous options, when you try to fill it's security holes, you often end up recreating proof of work, or recreating a memory hardened algorithm. I feel like this is one of the few logical directions with potential though.
We've watched things like PoS evolve where coin age had to be dropped due to being a security hole. PoW has a more uneventful evolution. I think people are eventually going to come to the conclusion these consensus methods standing on their own aren't good enough and have to be combined with something else to fill their weaknesses. Proof of burn is also a very underutilized tool that can be used to combat weaknesses in consensus mechanisms.
At first, I thought it was a giant weakness of cryptocurrency that coins lost per year, "zombie coins", could be extremely high, even estimated all the way up to 5% by some. A currency isn't supposed to be inflationary or deflationary, it's supposed to be a stationary unit of equilibrium for trade. If you can accurately model variables like this, this is not a detriment to your system, it's a security benefit, because you can do things like add a perpetual non-zero block reward to increase security, or add 2% annual stake to increase security without even causing inflation. In this manner, people who die with encrypted wallets are having their wealth transfered to miners to secure the network rather than the entire population by not spending their coins.
Bitcoin does not utilize this variable for security because there was no way for Satoshi to model the data at the time. Once the variable is known, the question is not should it be utilized, the question is, is the network most secure by adding this variable to PoW as a non-zero block reward, or does network security benefit the most by issuing this variable with proof of stake combined with another consensus mechanism? Since we know PoS most likely can't stand on it's own, the next question is, what other consensus mechanism can be combined with PoS in order for it to function and possibly negate weaknesses of PoW as well?
This post kind of jumped around in multiple trains of thought, but the general summary is, either PoW with a non-zero block reward will prove to be best, since it subsidizes transaction fees and security without a negative hit to economics, or something like PoC + PoS can be combined to defeat it.
