gtrubetskoy

18 ms·

31.
by gtrubetskoy 8y ago
> In verge's case, both are identical, at 2 hours. Naive question - is verge adjustment window defined in block time (as opposed to "human" time)? because > Bitcoin allows a 2 hour drift, but has an adjustment window of
32.
by gtrubetskoy 8y ago
My post merely shows that PoW is the mechanism via which this absolute timestamp (I like this terminology, BTW) is provided and seems very important, but I think the real question (to which I do not know the answer) is: can it be proven tha
33.
by gtrubetskoy 8y ago
Add to that - I do not see any mention of the source of timing or "timestamp server" as the Nakamoto paper refers to it. The details of why it is important are in my blog post here https://grisha.org/blog/2018
34.
by gtrubetskoy 8y ago
I forked Redis years ago providing threads and SQL support, though I can't remember if transactions were supported now. This was done mostly for fun and as an experiment, learned a lot about locking and database internals in the proces
35.
by gtrubetskoy 9y ago
It'd be interesting to know the length of a sequence that will never be sent over the Internet. In B. Schneier's "Applied Cryptography" there is a discussion of 256-bit numbers, the minimal amount of energy and mass re
36.
by gtrubetskoy 9y ago
> What is the point in time you mined block 12345 exactly? It is precisely this problem that Proof-of-Work (they way it's used in Bitcoin) solves. OK, I think I'm beat trying to explain this :)
37.
by gtrubetskoy 9y ago
OK, at the time the solution was found, and the miner went "hooray I solved a block!". That's exactly when the the blockchain clock ticked and on that tick the block was mined. You can't know precisely what "human&q
38.
by gtrubetskoy 9y ago
May be to understand it better consider the blockchain (i.e. how ticks are recorded) vs the actual ticks as they happen in "real life". At the risk of sounding like a broken record: when the SHA puzzle is solved is the exact
39.
by gtrubetskoy 9y ago
I like Proof-of-Tick :)
40.
by gtrubetskoy 9y ago
The valid sha ties this block to the exact point in time at which the solution was found. We can't know exactly what time in hh:mm:ss that was, but we do know the chain height, and the height is how "blockchain time" is told.
41.
by gtrubetskoy 9y ago
>> SHA is Memoryless and Progress-Free > Technically false, because memory-less processes have positive probabilty of yielding no block after 2^256 tries, whereas for sha-256 using brute force, this probability is totally 0. I don&
42.
by gtrubetskoy 9y ago
> the difficulty is not intergalactic because a solution on mars is much less useful than a solution on earth We're talking apples and oranges, I don't think there is a disagreement - I was only saying that the statistical prob
43.
by gtrubetskoy 9y ago
Think of it this way: the block is the input to SHA. When the puzzle is solved, that block happens exactly at the time the puzzle is solved, and no one cannot dispute it. There is no other way (or at least none that I can think of) to link
44.
by gtrubetskoy 9y ago
> Proof of work is the leader election phase of consensus. This is a common misconception stemming from looking at PoW through the Paxos/RAFT prism. In Paxos a leader is elected, then the leader decides the order of events. But that
45.
by gtrubetskoy 9y ago
You are right that PoW does not establish order. The PoW "ticks" have a temporal order, but the way it is represented in the blockchain is cryptographically using a Merkle tree, and there is no "rule" that the real lif
46.
by gtrubetskoy 9y ago
>> Mostly the claim that "The Difficulty is Intergalactic" is just flat wrong. (I wrote the article) - I see your point, but I think the article is still correct. Now communicating the winning block is a problem, as you po
47.
by gtrubetskoy 9y ago
>None of the addresses in your examples are the same. Check again: the first TX pays to 12Pws7qasVjt7uKfT6woQptx1MLNj2mo44, the second spends from it.
48.
by gtrubetskoy 9y ago
Yes (as sly010 pointed out), here is an example: https://blockchain.info/tx/cffa18e3d519c31c8624fc2c3e498c0d9... https://blockchain.info/tx/f24eaa493071e96f5bdf931204b893098... Both transactions a
49.
Proof-Of-Work is a Decentralized Clock(grisha.org)
232 points by gtrubetskoy 9y ago|124 comments
50.
by gtrubetskoy 9y ago
Well - the way you describe it is it's like Satoshi used a bread knife to cut something other than bread, but it's more like he used it as an antenna. He is exploiting a feature of HashCash that Adam Back (who invented it) didn&#x
51.
by gtrubetskoy 9y ago
> HashCash, ECC, Merkle trees etc... Just combined together in a clever way to create something that's more than the sum of their parts. No, not really. The way proof-of-work is used is nothing like in HashCash (more generally known
52.
by gtrubetskoy 9y ago
The problem that proof-of-work blockchain solves is widely misunderstood. It uses proof-of-work to establish consensus over points in time which are universally unique. Prior to the publication of Satoshi's paper we did not have a solu
53.
by gtrubetskoy 9y ago
Does this mean a "git pull" is vulnerable to this, or does git not rely on patch?
54.
by gtrubetskoy 9y ago
I was referring to the concept of delegating decisions to a (somehow selected) single node, though in those particular cases there is no "stake".
55.
by gtrubetskoy 9y ago
I definitely agree that PoW is very hard to understand because it is not a computer thing, it's about the relationship between large number theory, thermodynamics and statistics/probabilities. I describe it to myself as a clock, I
56.
by gtrubetskoy 9y ago
The only problem here is that Proof-of-Work is the evolution of Proof-of-Stake, not the other way around. PoS is how Paxos and RAFT work, and it was described in Wei Dai's b-money in 1989 [1]. But it didn't work for an adversarial
57.
by gtrubetskoy 9y ago
There is a book by one of the people who worked on the "novichok" agents which describes in detail the story behind and the chemicals themselves, including the exact formulas and some synthesis details. https://www.amaz
58.
by gtrubetskoy 9y ago
> do large mining operations network their miners so that they don't overlap their hashes The short answer is "no" (there is no need). The SHA-256 space (2^256) is larger than the number of atoms in the observable universe
59.
by gtrubetskoy 9y ago
A related statistical "mystery" is the miner cooperation without communication property of Proof-of-Work I describe here: https://grisha.org/blog/2018/01/23/explaining-proof-of-work/ It to
60.
by gtrubetskoy 9y ago
For programmers "understanding" graph theory begins with being able to implement a traversal and knowing how depth-first is different from breadth-first, what is pre-order, in-order or post-order, what role the stack and the queue

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