Digital content is rendered on a device by transferring the content to the
device and obtaining a digital license corresponding to the content. A sub-license
corresponding to and based on the obtained license is composed and transferred
to the device, and the content is rendered on the device only in accordance with
the terms of the sub-license. The content is encrypted and decryptable according
to a content key, and the sub-license includes the content key encrypted and decryptable
according to a secret. The sub-license also includes indexing information identifying
the secret to the device. The indexing information in the sub-license is obtained
to identify the secret, and the secret is acquired based at least in part on the
indexing information. The secret is then applied to the encrypted content key to
decrypt and obtain the content key, and the obtained content key is applied to
the encrypted content to decrypt and obtain the content. To compose the sub-license
and also to render the content, the secret is derived by obtaining a device identifier,
acquiring a super-secret, and applying the obtained device identifier and super-secret
to a function to derive the secret.