Disclosed are various embodiments relating to a security framework for media playback. In one embodiment, a client device has a decryption module, a streaming module, and a playback module. The playback module may be configured to request media data from the streaming module and render the media data on an output device. The streaming module may be configured to obtain the media data from the decryption module by a request that specifies a size of the media data. The size may be dynamically determined based at least in part on an amount of available temporary data storage. The decryption module may be configured to decrypt a portion of an encrypted media file based at least in part on the specified size to produce the media data.