Sentiment: use Bitcoin signatures to vote up messages

[killerstorm]

Sentiment is a bulletin board which uses Bitcoin for a Sybil-attack-resistant message ranking. User which supports a particular message can sign its hash using one of his addresses which holds some amount of bitcoins and submit this signature to Sentiment. Sentiment collects all signatures, computers a total amount of bitcoins which support a particular message and uses that for ranking. The idea is that this ranking corresponds to the sentiment of Bitcoin users weighted by the amount of bitcoins they own.

http://sentiment.memeexchange.com/

Note: Signing a message with your private key might have some security and privacy implications, effectively the same as Bitcoin address reuse. Publishing signatures increases risk in case of use of flawed wallet software or discovery of ECDSA vulnerabilities.

[avatar_kiyoshi]

AFAIK there are similar system like this, which you can vote with bitcoin signature and the vote is show your bitcoin balance on wallet.

[belcher]

Just came across this. Pretty nice.

Question is how to get a good readership.

Simple ideas, you've probably already thought of them:

Have buttons for sharing on twitter, facebook, reddit, etc etc Maybe limit the size of messages to be short like tweets.

Make it possible to load a single message in a page, for easier linking.

Make it possible to sort by top and new.

A history feed where new events appear e.g. "This new message was posted" "This message was supported by address 1XXXXX". However make sure it doesn't make it easier to destroy privacy e.g. many signatures appearing very close together in time probably means the addresses are all owned by the same person.

A graph of support vs time. Also a graph of support as a % of total support vs time. A message showing the total amount of bitcoins used to support on the site.

Link to this thread and the github from the sentiment main page.

On the Support page, display the message you are supporting.

[belcher]

What luke-jr writes on this reddit post is worth taking into account https://www.reddit.com/r/Bitcoin/comments/3kwwal/sentiment_a_message_board_which_uses_bitcoin/cv5m42q

The current system only works with pay-to-pubkey-hash addresses (starting with 1) Given that nearly 10% of all bitcoins are held in p2sh addresses, probably for security reasons, this excludes a lot of coin.
Also it slightly damages the fungibility, because certain bitcoins held in p2pkh can do more things than bitcoins held in p2sh.

It's probably better to reword the site, saying its based on the UTXOs instead of addresses. In bitcoin a UTXO is probably the closest analogy to a "coin". The code can probably stay the same, if a signature works for one UTXO on an address it will work for all others on that address. Then later you extend it to work with p2sh UTXOs.