class Aws::Signers::S3

def signing_string_date(request)
  # if a date is provided via x-amz-date then we should omit the
  # Date header from the signing string (should appear as a blank line)
  if request.headers.detect{|k,v| k.to_s =~ /^x-amz-date$/i }
    ''
  else
    request.headers['Date'] = Time.now.httpdate
  end
end