aws_cf_signer

# Pass in path to the private CloudFront key from AWS
signer = AwsCfSigner.new('/path/to/my/pk-1234567890.pem')

# If the key filename doesn't contain the key_pair_id (as it usually does from AWS), pass that in as the second arg
signer = AwsCfSigner.new('/path/to/my/private-key.pem', '1234567890')

# If your private key is not on the filesystem, you can pass it explicitly, you need to pass key_pair_id if you do that
signer = AwsCfSigner.new(ENV["CLOUDFRONT_PRIVATE_KEY"], '1234567890')

# expiration date is required
# See Example Canned Policy at above AWS doc link
url = signer.sign('http://d604721fxaaqy9.cloudfront.net/horizon.jpg?large=yes&license=yes', :ending => 'Sat, 14 Nov 2009 22:20:00 GMT')

# You can also use a Time object
url = signer.sign('http://d604721fxaaqy9.cloudfront.net/horizon.jpg?large=yes&license=yes', :ending => Time.now + 3600)

# Custom Policies

# See Example Custom Policy 1 at above AWS doc link
url = signer.sign('http://d604721fxaaqy9.cloudfront.net/training/orientation.avi',
  :ending   => 'Sat, 14 Nov 2009 22:20:00 GMT',
  :resource => 'http://d604721fxaaqy9.cloudfront.net/training/*',
  :ip_range => '145.168.143.0/24'
)

# See Example Custom Policy 2 at above AWS doc link
url = signer.sign('http://d84l721fxaaqy9.cloudfront.net/downloads/pictures.tgz',
  :starting => 'Thu, 30 Apr 2009 06:43:10 GMT',
  :ending   => 'Fri, 16 Oct 2009 06:31:56 GMT',
  :resource => 'http://*',
  :ip_range => '216.98.35.1/32'
)

# You can also pass in a path to a policy file
# This will supersede any other policy options
url = signer.sign('http://d84l721fxaaqy9.cloudfront.net/downloads/pictures.tgz',
  :policy_file => '/path/to/policy/file.txt'
)