Quote from: TheByzantineGeneral on March 04, 2017, 03:35:03 PM

Quote

Response to the Recent Attacks Against The Qtum Project:
via Slack - qtum-brett:

Many people following this thread may have noticed there have been attempts to discredit the Qtum project. One needs only to look at the tactics being employed. There is a term used commonly on this forum called: FUD, which Wikipedia.org describes as:

Fear, uncertainty and doubt (often shortened to FUD) is a disinformation strategy used in sales, marketing,public relations,talk radio, politics, religious organizations, and propaganda. FUD is generally a strategy to influence perception by disseminating negative and dubious or false information and a manifestation of the appeal to fear.

What we are seeing right now is exactly this, an attempt to undermine, call into question, create evidence, and in essence: Fud the project. Most veteran readers of this forum are familiar with this. The issue that legitimate projects face is by simply responding, the bar is lowered and it drags the project into the depths of internet trolling. By remaining anonymous, an accuser can simply post whatever they want as bait, regardless of of whether its false ortaken completely out of context. This does not mean we are hiding or afraid to post on our own channels, it means that we will not fuel attacks by giving them attention.

The Qtum project is a vast undertaking. Over the next 2 weeks as we lead up to the token sale, there will be a lot of content released that shows how we were able to raise $1 million in Angel backing and gather so much positive attention in the press. Please note that as source code starts to be released, and other content is presented, the attacks will persist. Please also remember that this is not the only big project that has experienced this and went onto become very successful.

These attacks have fallen completely flat on the Chinese community, as they recognize Fud for what it is, and they pay little attention to western channels like Bitcointalk. Qtums amazing team of Angel Backers have all experienced this type of behavior in the blockchain space, and none of these attacks affect their view of the project. Note that attempts to call into question their mere existence failed, and tactics were changed to attack the actual team members individually.

Our partnership with PwC remains firm, and legitimate concerns about the project (like how the funds will be handled,exchanges, token distribution, when the test network is released, etc) will be addressed. Right now the focus is on building the community, releasing content, press articles, and of course, the source code.

Very soon there will be a great opportunity to judge the project based on its accomplishments, above and beyond raising money and press attention. We ask that anyone affected by these attacks to take a sober second look at the project, and make their own informed decisions.Sincerely,The Qtum TeamMarch 3rd, 2017

so you know TheByzantineGeneral problems?

are you a developer?

can you tell me the difference of BFT and PBFT ?

Byzantine Generals Problem and its Applications
Byzantine General Problem
    The Classic Problem
   Each division of Byzantine army are directed its own general
   Generals, some of which are traitors, communicate each other by messengers
   Requirements:
   All loyal generals decide upon the same plan of action
   A small number of traitors cannot cause the loyal generals to adopt a bad plan
   The problem can be restated as:
   All loyal generals receive the same information upon which they will somehow get to the same decision
   The information sent by a loyal general should be used by all the other loyal generals
   The above problem can be reduced into a series of one commanding general and multiple lieutenants problem - Byzantine Generals Problem :
   All loyal lieutenants obey the same order
   If the commanding general is loyal, then every loyal lieutenant obeys the order she sends
Reliability by Majority Voting
    One way to achieve reliability is to have multiple replica of system (or component) and take the majority voting among them
   In order for the majority voting to yield a reliable system, the following two conditions should be satisfied:
   All non-faulty components must use the same input value
   If the input unit is non-faulty, then all non-faulty components use the value it provides as input
Impossibility Results
    No solution exists if less than or equal to 2/3 generals are loyal
A Solution with Oral Messages - No Signature
Oral Message Requirements and their Implications
    A1 - Every message that is sent is delivered correctly
   The failure of communication medium connecting two components is indistinguishable from component failure
   Line failure just adds one more traitor component
   A2 - The receiver of a message knows who sent it
   No switched network is allowed
   The later requirement -- A4 nullifies this constraint
   A3 - The absence of a message can be detected
   Timeout mechanism is needed
Solution
    If less than 1/3 generals are traitors, this problem can be solved
   Algorithm - recursive
   Lieutenants recursively forward orders to all the other lieutenants
   Commander's order = majority (v(c), v(1), v(2), ..., v(n))
   v(i) = majority (v(i), v(i)(2), v(i)(3), ..., v(i)(n)), 1<= i <= n
   v(i)(j) = majority (v(i)(j), v(i)(j)(3), v(i)(j)(4), ...)
   ...
A Solution with Signed Messages
Additional Requirements and their Implications
    A4:
   A loyal general's signature cannot be forged
   Anyone can verify the authenticity of a general's signature
   Implication
   Digital signature is required
Solution
    If at least two generals are loyal, this problem can be solved
   Algorithm - recursive
   Lieutenants recursively augment orders with their signature and forward them to all the other lieutenants
   Each lieutenant maintains a set of orders she has received, i.e., the possible sets are:
   { attack },
   { wait }, or
   { attack, wait }
   Lieutenant takes action according to the value of the set
   { attack, wait } means the commander is a traitor
Missing Communication Paths

Network topology or policy could keep a general sending/receiving messages to/from another general

This constraint makes Byzantine problem more general
Oral Message
    If the communication graph is 3m-regular and less than or equal to m generals are traitors, this problem can be solved
   k regular set of neighbors of a node p
   the set of all neighbors of p, whose size is k
   for any node not in the set, there exists a disjoint path, not passing through the node p, from a node in the set
   k regular graph - every node has k regular set of neighbors
   Algorithm - extension of oral message
   Lieutenants recursively forward orders to all its k regular neighbors
   Commander's order = majority (v(c), v(1), v(2), ..., v(n))
   v(i) = majority (v(i), v(i)(2), v(i)(3), ..., v(i)(n)), 1<= i <= n
   v(i)(j) = majority (v(i)(j), v(i)(j)(3), v(i)(j)(4), ...)
   ...
Signed Message
    If the subgraph of loyal generals is connected, this problem can be solved