Hello!

What limit exactly would you suggest? Even if you're allowed to put only 10 additional bytes per transacton, you can make up for it by increasing the number of tour transactions.

And what kind of misuses do you have in mind?

I doubt it is possible. How a PoW node can be penalized? Any miner can just restart with another wallet after finding a block.

PoS mining is already penalized, in a manner of speaking. The "winning" output cannot be used in PoS mining again immediately: the funds must remain untouched for at least 1 day. But it doesn't affect the other outputs: their probabilities of winning are independent (like for several different PoW miners).

Hello everybody!

We want to post some updates on our protocol. Your comments are very welcome. Please, read the pdf first (the part about PoS).

 - The kernel structure now includes last_pow_hash and last_pos_hash: blockID of the last PoW block and kernel hash of the last PoS block respectively. By that we create the true chain of blocks. In PPC you can use your winning output whenever you want (within timestamp boundaries), because kernel does not depend of the prevous block (unlike PoW mining, where block header includes prev_id). Even use it twice (if a chain fork occurs). Our protocol prevents it, making PoS mining more like PoW (but energy-efficient).

 - StakeModifier (a part of the kernel) is recalculated on each PoW block as follows: StakeModifier on height h is equal to keccak(H20,H720), where H20 is the proof_hash of the block on height h-20 (20 blocks ago) and H720 is the proof_hash of the block on height h-720. proof_hash is blockID (for PoW) or kernel-hash (for PoS). Now StakeModifier is known in advance, 20 blocks ahead. But due to the first change an attacker can't predict his chances of creating consecutive chain of PoS blocks: he doesn't know pow_hash.

 - Timestamp boundaries become more narrow. Timestamp must be greater than the median of the last 20 blocks (each block appears ~every 2 min, so the median is t minus 20 minutes). And it shouldn't be greater than t+20 minutes, where t is the current local time of a node. The first rule is a mandatory one (we check it while verifying the blockchain), and the second is a default local node policy (we can not check it for blockchain in the past). This change is intended to decrease the power of PoS exhaustive search and make timestamps more consistent.

Any questions, please?

Quite the contrary. Eliminating age prevents a situation when adversary can "take over the chain" with less than 51% (accumulating his coin age). That the reason why PPC code anyway bounds age by 90 days (and still preserves the benefits for large holders).