class OauthUtil

def signature

@ref http://oauth.net/core/1.0/#rfc.section.9.2 
def signature
  key = percent_encode( @consumer_secret ) + '&' + percent_encode( @token_secret )
  # ref: http://blog.nathanielbibler.com/post/63031273/openssl-hmac-vs-ruby-hmac-benchmarks
  digest = OpenSSL::Digest::Digest.new( 'sha1' )
  hmac = OpenSSL::HMAC.digest( digest, key, @base_str )
  # ref http://groups.google.com/group/oauth-ruby/browse_thread/thread/9110ed8c8f3cae81
  Base64.encode64( hmac ).chomp.gsub( /\n/, '' )
end