Some time ago I wrote a article explaining how to guarantee the anteriority of a document (the timestamp), as well as the author, using the bitcoin block chain, by sending a small amount to a particular address.
An alternative is to use the Domain Name System, and to register a hash as a new domain, which will be associated to your name in the international registry database - thus verifiable by anybody.
The only limitation is the size of the domain that can be registered. If SHA-256 bits (32 bytes) is too much, you can still use SHA-224 (28 bytes) that still provides a good level of security.
As an example, you can have a look at the http://399e1c10559be82bca07619ff530b9c0752a0ec27d2e8cbd1970a1b5.info website.