However, there are special cases in which it is reasonable to require high entropy messages. For example, encryption schemes that encrypt only secret key material (e.g., key encapsulation or Key Wrap schemes) can be considered under an entropic security definition.
In certain circumstances, it is reasonable to expect high-entropy messages. To provide an illustration, cryptographic techniques that encrypt only sensitive key information (such as key encapsulation or Key Wrap algorithms) are considered to have entropic security characteristics.