How to exploit the possibilites of blockchain for proof of authorship? I want to to create some kind of Proof-of-Authorship mechanism, that's something that many artists had asked before: How can I prove authorship of my work 

To accomplish my objective I need to deal with 2 problems: 


first, how to precisely and uniquely define a work, and 
second, use something like a public ledger to store and validate that information.


I will think about first later; it's a very complex problem; I want to know if I could use the blockchain for the second one. (If you can give me some suggestions for the first problem they will be appreciated too.)
If expressing the (artistic) work in any kind of document (be it sheets, photos or audio/video recording) is good enough, then you can use something called proof of existence. This simple method allows you to store a hash of any document into the Blockchain, thus proving it existed at the time when a particular block was mined.

You can indlude the autor's name (or other identifier) into the document, making it clear that he (at least) knew about it back then. If nobody proves the possesion/familiarity with that particular file/work dated before, the author should be able to claim his rights.

One (perhaps the first) proof-of-existence service is proofofexistence.com.