KudosA Peer-to-Peer Discussion System

Based on Social Voting

Luca Matteis lmatteis@gmail.com

Social Voting (online discussions)

Nothing decentralized exists for discussing online using social voting. Central entities have control over what can

be discussed. Could alter users reputation.

Challenges for decentralized systems: Who keeps track of user's reputation?

Where is information stored and retrieved?

distributed hash table

peers

blockchain

key

key

get(key)

put(key, val)

Incentives

• Similar to Bitcoin: mine and get points. • Universal fixed amounts make it uneconomical to

use for trading. • To earn points users post content that others are

willing to upvote.

Transaction (vote): Input —(key)—> Output

A—(a)—>B C—(d)—>D D—(a)—>A B—(c)—>A

B—(b)—>A B—(d)—>C C—(b)—>D

A—(a)—>C C—(d)—>C D—(c)—>B

4 users: A, B, C, D 4 DHT keys: a, b, c, d

block #300block #299block #298

points(user A) = Outputs(A) = 3 points(key b) = key(b) = 2

A—(a)—>B C—(d)—>D D—(a)—>A B—(c)—>A

B—(b)—>A B—(d)—>C C—(b)—>D

A—(a)—>C C—(d)—>C D—(c)—>B

4 users: A, B, C, D 4 DHT keys: a, b, c, d

block #300block #299block #298

Most relevant keys: a = 3 d = 3 b = 2 c = 2

DHT

Transaction (vote): Input —(key)—> Output

Keys in the latest block are fresher because they are pushed more often to the DHT points(user A) = Outputs(A) = 3

points(key b) = key(b) = 2

peer

What's relevant lately?

1. get most relevant keysfrom the blockchain

keys: a: 30 points, b: 45 points

distributed hash table

2. get() the keys from the DHT

3. push() the keys to keep them alive in the DHT

peer

Publish content.Content has a key = k and a value = "Hello World"

1. push(k, "Hello World") to the DHT

distributed hash table

2. make a transaction (vote) with k inside and soon it will be mined in a block

Transactions universal fixed amount

Problem: same user might have several addresses

1EzwoH… 1AZyMz…50 points

They could send votes with specific key to themselves to promote their own content

(key)

Transactions universal fixed amount

(constant)

With universal fixed amounts, transactions are of an atomic value.

1EzwoH… 1AZyMz…

To send 50 points, he now needs to break it into 50 transactions (with amount=1)

1E..0

1…..

1…..

1..N-1

1….N

1 point 1 point

amount = 1

Transactions universal fixed amount

Each transaction also requires a fixed fee

1EzwoH… 1AZyMz…

To send someone a point (a vote) it requires 2 points from the sender: 1 for the receiver, 1 for the miners.

Sending 10 points to someone would require 10 addresses with at least 2 points each. Creating 10 addresses with 2 points each, would

require 10 transactions of 4 points each, meaning 40 points.

1E..0

1…..

1…..

1..N-1

1….N

2 points (1 fee, 1 receiver)

tx amount = 1 fee amount = 1

Keep aliveTransactions in the latest blocks are republished more

frequently to the DHT to enable quicker response times. Intuition: latest content is more frequently fetched.

higher republish ratelower republish rate

This means old content might not be present in the DHT anymore. System only works well for latest

content: it's not meant to function as a permanent storage system (although DHT keys will remain

permanently in the blockchain).

Groups subscriptionContent can be categorized under specific groups such as: sports, videos, politics, astronomy, etc. to enable creation of

communities (subreddits).

higher republish ratelower republish rate

Users subscribe to specific groups and their republish rate is biased towards content they're subscribed to. Intuition: smaller communities might die off into old blocks, therefore subscribers can help store that

content for longer periods of time in the DHT.

Userasubscription = soccer

DHT structure

• Hierarchical structure of comments to enable discussion (replies/responses are nested).

• Two types of content: posts and comments. • Store little information (limited amount of bytes

needed for comments/posts). • Groups can be assigned to posts to categorize

content and enable creation of communities. • Blockchain doesn't care about this at all (all it needs

is a reference).

Use cases

45128

119

1890

Decentralized reputation

Freedom of speech

Proof of what anybody said available in the blockchain

Relevant content stands out