Generate timestamped signature

gistfile1.rb

#!/usr/bin/env ruby
require 'digest/md5'
require 'base64'

if ARGV.length != 1
  $stderr.puts "usage: #{$0} secret"
  exit 1
end

timestamp = Time.now.to_i
key = [timestamp, ARGV[0]].pack('NZ*')
hash = Digest::MD5.digest(key)
signature = [timestamp, hash].pack('NZ16')

$stdout.puts Base64.urlsafe_encode64(signature).sub(/=+$/, '').chomp