Petahash Attack on Susucoin

The Attack

During the end of July and the beginning of August, Susucoin sustained a series of hash attacks.  In the following graph we see hash per second spikes for few minutes at a time.  Susucoin recovered quickly because we use a state of the art difficulty algorithm.

Why do we call this an attack?  Because the miner with this hashing power only mined Susucoin for a few minutes at time and then left.  Hoping perhaps that the regular miners, with the hashing power seen at the very bottom of the above graph, would take weeks to recover.

We focus on the period between midnight July 28th and midnight July.  This is the period with the highest hash rate per second as the network measures it —this may be different from the hashing power of the mining equipment used for the attacks.

Notice that these are two distinct graphs superimposed, the difficulty is on the right, while the hash/second graph is on the left — they are not the same scale.  The points show each mined block and the hash rate as measured by the network, and the difficulty of the mining operation.

We see that the first mined block after attack still has a high difficulty, after which it drops sharply before teetering down to normal over the course of 12 hours or so.  After the former attack seen on the graph, the difficulty did not have time to get back to normal before the second attack.

The Difficulty Algorithm

Susucoin uses state of the art linearly weighted moving average or LWMA algorithm.  This gives more weight to the most recently mined blocks and protects us from hash attacks as can be seen, as well as timestamp manipulations.

At the time of writing, we use an averaging window of 60 blocks, with the least weight given to the oldest block, and most weight given to the most recently solved block.

Read more about LWMA.