Support for Access Keys

Certain compression formats, such as the Intel® Indeo® format for video compression, allow data to be encrypted when it is compressed. For software to gain access to the encrypted data, the access key for the data must be registered with QuickTime. For example, a CD-ROM title would register one or more access keys for encrypted video data it presents. Once the access keys are registered, the keys are available to the decompressor component that will be used decompress the data. The CD-ROM title can then use the encrypted data in the same way it uses unencrypted data.

QuickTime 3 includes functions that allow software to register, unregister, and get access keys. In addition, the QuickTime control panel lets users enter, delete, and modify access keys.

Although most access keys are character strings, an access key can be of any data type.

Scope of Access Keys

The scope of an access key is determined when it is registered. If a key is registered as a system access key, data protected by they key is available to any QuickTime client on the computer. If a key is registered as an application access key, data protected by the key is available only to QuickTime clients of the application that registers the key. For example, if a single access key is used to encrypt all the data on a CD-ROM, and the CD-ROM title registers the key as an application access key, the data on the CD-ROM is available only to the title and inaccessible to all other applications. This prevents users from browsing through data on the CD-ROM that is meant to remain hidden.

Access keys entered in the QuickTime control panel are always registered as system access keys.

Access Key Types

Access keys are grouped by type. For example, there can be an access key type specifically for the Intel Indeo video decompressor. Grouping access keys lets a decompressor request only those keys that apply to it. This speeds operations involving large numbers of keys which might otherwise interfere with the performance of real-time operations. The functions for using access keys all require an access type.