LikeCoin

LikeCoin creates unique fingerprints for creative contents and traces footprints of all derivative works along with content creator and service provider of them. Further than that, LikeCoin incentivises attribution and cross-application collaboration with Proof of Creativity mechanism.

The cornerstone of LikeCoin protocol is a global, decentralised and resilient creative content library on IPFS.

A LikeCoin service provider plays one or more roles among original creator, content adopter and content distributor. Original creators curate creative contents and record the data on blockchain for other content creators to use. The content creator and the
service provider both get LikeCoin as an incentive when a content is Liked or Super-liked (see LikeCoin Mining Protocol). Two major original creators funded by LikeCoin Foundation will be puttyimages, an open stock image DApp (decentralized application)
and blogchain.md, a blogging DApp which records each post on a LikeCoin smart contract. A content distributor, on the other hand, displays or plays the creative contents in the LikeCoin ecosystem.

Each original creator and content adopter runs her own IPFS node and is responsible
for pinning all the files she curates from content creators so they are not removed. Since

worldwide IPFS nodes help one another distribute the contents, such decentralised creative content library also serves as a content distribution network, speeding up access from locations unreachable by Internet backbone. Service providers do not have to be concerned about from which IPFS node users will retrieve the content.

In the library, each creative content is addressable by a cryptographic hash rather than a URL. Any changes in the application layer such as domain name, IP and directory structure induce no change to the content address since the hash depends only on the content itself. The content address is thus decoupled from the application where it was created on and where it is used, making it consistent and future-proof. This prevents creative contents from being locked up by specific applications such as Facebook and Instagram. Such cryptographic hash is called content fingerprint in the LikeCoin protocol. A unique, one-to-one content fingerprint of each file is generated by the SHA-256 hash function. Metadata of the images are stored off-chain as an IPLD object (see section Metadata Objects below) on IPFS. Only the metadata hash and the content fingerprint are written to the Ethereum blockchain with the private keys of the service providers through a LikeCoin smart contract. Such two-tier architecture maximises speed and flexibility while minimising the gas needed to write to Ethereum.

Metadata are stored as IPLD objects, which are linked objects that can contain reference hash of other IPLD objects and build a path across them. Since IPLD objects are stored on IPFS, they are represented by 1-to-1 hashes as well. Such feature is used to build content footprint of every creative content, to be discussed in the next section. Three kinds of IPLD objects are defined in the LikeCoin protocol following schema.org's ImageObject schema. They are content metadata object, service provider object and content creator object, three of which are all interconnected through hashes of the objects. Content fingerprint is like the DNA of a creative content, while content footprint is like the family tree of it. For every derivative work in LikeCoin protocol, IPLD references of the content sources are recorded in a footprint array in the metadata object.

Based on content footprint tracing in the LikeCoin protocol, LikeRank measures the importance, or creativity as we define it in this context, of a creative content. In general, the more derivative works a creative content generates, the more creative the creative content is, and thus the higher LikeRank of the content. LikeRank is the quantifier of the creativity of contents.

LikeCoin’s Like button is designed to combine the “appreciate” and “pay” user experiences into one. By tapping/clicking the Like button for 1 to 5 times, or long press/hover then drag to 1-5, a user shows his/her appreciation and helps the content creator to mine LikeCoin from Creators Pool. If the user really appreciates, s/he may go directly to “Super Like” to pay the content creator certain amount of LikeCoin from his/her own wallet.