The shortDOI Service creates shortened DOI® names, of the form 10/abcde, as aliases for existing DOI names, which are often very long strings.
It is a public service, offered by the International DOI Foundation, that is open to anyone.
The service will either create a new shortDOI, or return the existing shortDOI if one has already been created. Applications which resolve DOI names will treat the shortDOI identically to the original.
http://shortdoi.org/