Topic: "Bitcoin" Unlimited Officially #REKT - page 3. (Read 2957 times)

It is more dirty nonsense by the Blockstream bastards who want to own Bitcoin for themselves.  Sort of a last desparate attempt to regain some lost ground.  Don't worry, it won't work.  Nobody is fooled.  Jihan should hash away as best as he can and so should anyone else.  If he boosts his ASIC, so be it.  Totally fair.  The others can boost theirs too.

Is this really the end for bitmain and Bitcoin Unlimited? Are they really cheating and doing something unwanted against the bitcoin system? These are just some of the questions I would like to search for but eventually all I can see in the forum was the collision of groups and that BU and bitmain were the evil empire trying to take and invade bitcoin country.

[bitcoin-dev] BIP proposal: Inhibiting a covert attack on the Bitcoin POW function

Gregory Maxwell greg at xiph.org
Wed Apr 5 21:37:45 UTC 2017

A month ago I was explaining the attack on Bitcoin's SHA2 hashcash which
is exploited by ASICBOOST and the various steps which could be used to
block it in the network if it became a problem.

While most discussion of ASICBOOST has focused on the overt method
of implementing it, there also exists a covert method for using it.

As I explained one of the approaches to inhibit covert ASICBOOST I
realized that my words were pretty much also describing the SegWit
commitment structure.

The authors of the SegWit proposal made a specific effort to not be
incompatible with any mining system and, in particular, changed the
design at one point to accommodate mining chips with forced payout
addresses.

Had there been awareness of exploitation of this attack an effort
would have been made to avoid incompatibility-- simply to separate
concerns.  But the best methods of implementing the covert attack
are significantly incompatible with virtually any method of
extending Bitcoin's transaction capabilities; with the notable
exception of extension blocks (which have their own problems).

An incompatibility would go a long way to explain some of the
more inexplicable behavior from some parties in the mining
ecosystem so I began looking for supporting evidence.

Reverse engineering of a particular mining chip has demonstrated
conclusively that ASICBOOST has been implemented
in hardware.

==Motivation==

Due to a design oversight the Bitcoin proof of work function has a potential
attack which can allow an attacking miner to save up-to 30% of their energy
costs (though closer to 20% is more likely due to implementation overheads).

Timo Hanke and Sergio Demian Lerner claim to hold a patent on this attack,
which they have so far not licensed for free and open use by the public.
They have been marketing their patent licenses under the trade-name
ASICBOOST.  The document takes no position on the validity or enforceability
of the patent.

There are two major ways of exploiting the underlying vulnerability: One
obvious way which is highly detectable and is not in use on the network
today and a covert way which has significant interaction and potential
interference with the Bitcoin protocol.  The covert mechanism is not
easily detected except through its interference with the protocol.

In particular, the protocol interactions of the covert method can block the
implementation of virtuous improvements such as segregated witness.

Exploitation of this vulnerability could result in payoff of as much as
$100 million USD per year at the time this was written (Assuming at
50% hash-power miner was gaining a 30% power advantage and that mining
was otherwise at profit equilibrium).  This could have a phenomenal
centralizing effect by pushing mining out of profitability for all
other participants, and the income from secretly using this
optimization could be abused to significantly distort the Bitcoin
ecosystem in order to preserve the advantage.

Reverse engineering of a mining ASIC from a major manufacture has
revealed that it contains an undocumented, undisclosed ability
to make use of this attack. (The parties claiming to hold a
patent on this technique were completely unaware of this use.)

On the above basis the potential for covert exploitation of this
vulnerability and the resulting inequality in the mining process
and interference with useful improvements presents a clear and
present danger to the Bitcoin system which requires a response.