How can I timestamp my paper without violating double-blind review? I submitted a paper to a top tier conference and it did not get accepted. The paper contains an original idea, and I am afraid that the paper could get plagiarized between the time I send it to another conference after incorporating reviewer's suggestions and making some modifications. Such things have happened in the past to a few students in my department.

I had considered posting the paper on arxiv as a means of timestamping before sending it to the aforementioned conference, but didn't, as this would have violated the double-blind review requirements of the conference. (The conference chair replied to my query as follows:)


  The submission of a paper in the arxhiv.org system is not strictly
  speaking a double-submission, but rather a violation of a double-blind
  submission required in this conference, as the reviewers will be able to
  find your name (and those of the coauthors) if they do a simple search
  in Google. Thus, I am quite certain it will be rejected, and I do not
  consider it an acceptable practice in this conference's submission to be 
  fair with all the submissions in order to handle them equally during the
  review process by the reviewers.


Hence I had not posted it on arxiv. Now this paper has been rejected and I would like to timestamp this paper now, while still being able to send a modified version to some conferences in the future (including those that follow a double-blind review). 

Is there a mechanism by which I can timestamp my paper that does not violate the blind review requirements? 

Edit: The paper was in computer science, if that matters.
A related question "How can I time-stamp my data without publishing it?" asks about ways to timestamp while keeping the information in the paper private or hidden to avoid plagiarism. However my question is about ways to timestamp such that it is still possible to publish the information while not violating blind review.
The most typical way to time-stamp a piece of work is to place it in a public repository: arXiv is a good example when it applies; many institutions also have a technical memo or technical report system in place.  Although this may technically violate certain interpretations of double-blind submissions, as noted in the comments blinding of authorship is pretty iffy in many cases.  Moreover, in practice this will only be violated if the reviewers actively go looking, particularly if you put it in an institutional repository rather than a global one like arXiv.  I would thus advise that if you are worried about date-stamping, just do it and let the double-blind nitpickers complain if they even notice.

One other consideration: certain publications (particularly certain journals) do have a policy against accepting material that is already available online.  While this is in my view an insane policy, if you find yourself dealing with such, one way to handle with it is to put up a shortened version of the work, i.e., extended abstract, as the date-stamped pre-print.