Since I'm not a developer nor a hacker I cant modify wallets to do such an attack, but here's the concept, which may not be right, but crackers may try.
We're going to exploit low PoS difficulty and prominently it's low for even 100% PoS coins. Like for mintcoin it's 0.243, even for popular and old coins like PPC, the difficulty is 10.
First let me explain the significance of difficult in PoS which's very much similar to difficulty in PoW. But don't assume low PoS difficulty means higher rate of returns. Each block gives the miner variable rewards depending on the current difficulty which predicts the probability of the coins to mint a PoS block. A low difficulty means the coins will easily be able to mint PoS blocks, since the number of PoS blocks generated by coins are frequent, the block reward will drop cause the interest rate is capped. In other words, when difficulty is low, the coins will have to wait less to generate a block reward, i.e. the coin will have less age so the block reward will be low. Similarly if the difficulty is high the block reward will increase cause the probability of the coins to make a PoS block will be less, so PoS blocks generated by the coins will be less but the interest rate has to be maintained at 20%; so to compensate for the lower block rate, the block reward will increase.
In PoS, when a node receives a number of coins all in 1 transaction (call this transaction X and the no. of coins in the transaction as A), all of these coins will be used to mine a block. The more the no. of coins in X, the higher the chance of hitting a block. The older transaction X goes the higher the chance of hitting a block. For coins which were received in another transaction (apart from X, call this transaction Z) but to the same address will try to mine a block separately from Z; the wallet will use Y along with X independently to mine blocks.
Suppose the probably of mining a block for X is within x days, after mining, the coin age renews to 0, making it ineligible to mine a block till it's old enough to mine blocks again.
We're going to compare the set of coins X which were received with in a single transaction to a no. of transactions the size of each being 1 coin, but the no. of transactions is such that it results in A no. of coins (i.e. A no. of transactions). This mean for each of these coins, the wallet will try to generate a block using them separately. Let's call this set of coins Y.
The probability of one coin to generate a block is x/A (since X has A no. of coins); for all of A no. of coins used together, the probability to generate a block is (x/A)*A = x. So Y has the same probability to generate a block as compared to X. Once a block has been mined, the age of the single coin used to mine a block becomes 0 and it comes ineligible for mining, but all other coins are still eligible for mining. Now the probability of Y to generate another block is (x/A)*(A-1) which is almost x (call this changing value y, i.e. y is the current mining power of Y after a no. of coins's age has been reduce to 0). Depending on the size of A, the this value of y will almost be the same as x for (x/A)*(A-1), (x/A)*(A-2), (x/A)*(A-3)... (x/A)*(A-100). The larger the value of A, the closer is the mining power to x as a single coin will be less significant for a large value of A.
So Y has lot more power to generate blocks as compared to X with the same no. of coins. The attacker with possession of Y can wait for an attack till the coins become older which yields better probability of blocks. (
update) In fact, the probability of generating a single block by splitting stakes (Y) is more effective than the regular X method. The reason being, as the no. of coins increases, the probability of hitting a block does not increase linearly (see
this); it's increment rate decreases. So the network difficulty is lower. But if you've split your stake (as with Y), the probability of staking a block will increase linearly, cause each coin has it's own staking instance. It's stake is calculated separately.
In a 51% attack block mining power is exactly what you need. You try to fork the block chain and try to make the forked chain longer than the main chain and once that happens all valid transactions in those chains will be lost (double spending). So when it comes to hashing power, PoS is more vulnerable to PoW.
It's a fallacy that you need most of the coins in a PoS coin to attack it; it all depends on the difficulty. You can do an attack even if you have less than 1% of the coins. It's all on the difficulty.
If you do a mindless criticism (criticizing me without any reason or calling the whole text gibberish without stating a reason), realize that it's clear that you own a huge stake in a 100% PoS crypto and are planning to dump it at a pump which this article may reduce the probability of (if it is true).
If you don't believe me, very well. I got no issues, but I'm always open for constructive discussion. As of attackers, they may try this and succeed while you believe this's a lie.
