Simple S3 signing for expiring URLs

s3sign.py

#!/usr/bin/env python
import os
import sys
import hmac
import time
import urllib
import base64
import hashlib
import urlparse

expires = int(time.time() + int(sys.argv[1]))
url = urlparse.urlparse(sys.argv[2])
access_key = os.environ["AWS_ACCESS_KEY_ID"]
secret_key = os.environ["AWS_SECRET_ACCESS_KEY"]

h = hmac.new(secret_key,
             "GET\n\n\n%d\n%s" % (expires, url.path),
             hashlib.sha1)

sign = urllib.quote_plus(base64.encodestring(h.digest()).strip())

print("%s?AWSAccessKeyId=%s&Expires=%d&Signature=%s" % (sys.argv[2],
                                                        access_key,
                                                        expires, sign))