Critical vulnerability in difficulty retarget algo

[xiphon]

Hello, i'm running FairPool ETP mining pool https://etp.fairpool.xyz.
15 Mar 2018 i've noticed some strange activity on the blockchain.

This looks like a critical flaw in the ETP difficulty retarget algo:

Is possible to lower the diff below the real expected value, supplying the blockchain with the blocks with altered timestamp set to
previous block timestamp + 24 sec

https://github.com/mvs-org/metaverse/blob/master/src/lib/blockchain/validate_block.cpp#L301

bool validate_block::is_valid_time_stamp(uint32_t timestamp) const
{ 
    // Use system clock because we require accurate time of day.
    typedef std::chrono::system_clock wall_clock;
    const auto block_time = wall_clock::from_time_t(timestamp);
    const auto two_hour_future = wall_clock::now() + time_stamp_window;
    return block_time <= two_hour_future;
}

https://github.com/mvs-org/metaverse/blob/master/src/lib/consensus/common/libdevcore/BasicType.cpp#L148

    static uint32_t time_config{24};
...
    if(_bi.timestamp >= _parent.timestamp + time_config)
    {
		target = _parent.bits - (_parent.bits/1024);

[aleqx]

Are blocks then being orphaned? What's up with the diff dropping 4x in a matter of hours - or is that unrelated?

[betachen]

5c10ed0

[betachen]

see https://docs.mvs.org/news/