A KOI 18 is considered what type of device?

A KOI 18 is classified as a fill device, which is used to securely transfer cryptographic keys into communication and encryption devices. Fill devices are crucial in maintaining the security and integrity of communications by ensuring that the correct encryption keys are utilized in securing sensitive information. They enable the proper loading of keys into equipment that requires them for encrypting and decrypting messages.

The functionality of fill devices is essential within the COMSEC (Communication Security) framework, as it prevents unauthorized access to cryptographic keys and helps maintain secure communications. The design and purpose of a KOI 18 specifically align with the criteria for fill devices rather than other categories such as encryption, storage, or destruction devices. Each of those other types serves different functions within the realm of secure communications, but they do not encompass the role that a KOI 18 fulfills.