After the metadata is set, you must create an HMAC-SHA1 (RFC 2104) signature. When you generate the TempURL, you determine which method of access you will grant users, GET or PUT. You also determine the path to the object you are granting access to. Lastly, set the time for your TempURL to expire in UNIX epoch notation.
In the below examples, a TempURL is generated for the object my_cat.jpg,
which will be available for 60 seconds. The key in the below
example is the X-Account-Meta-Temp-Url-Key.
Example 6.2. Create TempURL (in python)
import hmac
from hashlib import sha1
from sys import argv
from time import time
if len(argv) != 5:
print 'Syntax: <method> <url> <seconds> <key>'
print 'Example: GET https://storage101.dfw1.clouddrive.com/v1/' \
'MossoCloudFS_12345678-9abc-def0-1234-56789abcdef0/' \
'container/my_cat.jpg 60 my_shared_secret_key'
else:
method, url, seconds, key = argv[1:]
method = method.upper()
base_url, object_path = url.split('/v1/')
object_path = '/v1/' + object_path
seconds = int(seconds)
expires = int(time() + seconds)
hmac_body = '%s\n%s\n%s' % (method, expires, object_path)
sig = hmac.new(key, hmac_body, sha1).hexdigest()
print '%s%s?temp_url_sig=%sAMP;temp_url_expires=%s' % \
(base_url, object_path, sig, expires)
Be certain to use the full URL to the object, just as you would with a normal request.
In this example, the signature might be da39a3ee5e6b4b0d3255bfef95601890afd80709 and the expire time might translate to 1323479485" because the signature and expires completely depend on the time the code is run. On your website, you would provide a link to the below URL:
https://storage.clouddrive.com/v1/AUTH_account/container/my_cat.jpg?
temp_url_sig=da39a3ee5e6b4b0d3255bfef95601890afd80709&
temp_url_expires=1323479485
If you do not provide users with the exact TempURL, they will get 401 (Unauthorized) status errors. HEAD queries are allowed if GET or PUT are allowed.
Example 6.3. Create TempURL (in PHP)
<?php
if ($argc != 5) {
echo "Syntax: <method> <url> <seconds> <key>";
echo "Example: GET https://storage101.dfw1.clouddrive.com/v1/" .
"MossoCloudFS_12345678-9abc-def0-1234-56789abcdef0/" .
"container/my_cat.jpg 60 my_shared_secret_key";
} else {
$method = $argv[1];
$url = $argv[2];
$seconds = $argv[3];
$key = $argv[4];
$method = strtoupper($method);
list($base_url, $object_path) = split("/v1/", $url);
$object_path = "/v1/$object_path";
$seconds = (int)$seconds;
$expires = (int)(time() + $seconds);
$hmac_body = "$method\n$expires\n$object_path";
$sig = hash_hmac("sha1", $hmac_body, $key);
echo "$base_url$object_path?" .
"temp_url_sig=$sig&temp_url_expires=$expires";
}
?>
Example 6.4. Create TempURL (in Ruby)
require "openssl"
unless ARGV.length == 4
puts "Syntax: <method> <url> <seconds> <key>"
puts ("Example: GET https://storage101.dfw1.clouddrive.com/v1/" +
"MossoCloudFS_12345678-9abc-def0-1234-56789abcdef0/" +
"container/path/to/object.file 60 my_shared_secret_key")
else
method, url, seconds, key = ARGV
method = method.upcase
base_url, object_path = url.split(/\/v1\//)
object_path = '/v1/' + object_path
seconds = seconds.to_i
expires = (Time.now + seconds).to_i
hmac_body = "#{method}\n#{expires}\n#{object_path}"
sig = OpenSSL::HMAC.hexdigest("sha1", key, hmac_body)
puts ("#{base_url}#{object_path}?" +
"temp_url_sig=#{sig}&temp_url_expires=#{expires}")
end
