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DS-102 →
DS-101   EKMS 603
Common fill interface protocol

DS-101 is the current interface standard for electronic transfer devices, or fill units, developed and endorsed by the US National Security Agency. It superceedes the older DS-102 standard and is supported by nearly all modern radio sets and encryption devices, although most equipment is still backwards compatible with DS-102. DS-101 is supported by FILL devices like the AN/CYZ-10 and is described in the EKMS 603 standard. Unfortunately, this standard is not publicly available.

It is known however, that DS-101 is an asynchronous serial protocol, commonly implemented as an RS-485 interface, but RS-232 versions exist as well. In many cases, FILL devices support the newer RS-485/RS-232 asynchronous interface, as well as the older synchronous interface. Unlike the DS-102 standard, which could only transfer cryptographic keys and frequency hopping data, DS-101 can also be used for updating cryptographic algorithms and for new software releases.

DS-101 fill units on this website
AN/CYZ-10 Data Transfer Device
DS-101 compatible devices on this website
Narrow-band Voice and Data Terminal KG-40A Replenishment
For connection between the FILL unit, and a radio or encryption device, most devices used a standard U-229 connector. In many cases, this connector is shared with the audio functions of a military radio, for example for the connection of a handset. This connector has 5 or 6 spring-loaded contacts, and is available in a male and female variant, as shown in the diagram below.

Although each variant has its own specific type number, they are often referred to as U-229/U, or simply U-229, after the female 5-pin cable part. The table below shows the pinout of this connector for the DS-102 standard. On encryption devices this connector is commonly used exclusively for the FILL function, but on radio sets it is often shared with the audio functions.

Pin DS-101 Description Note
A GND Ground (common wire)  
B RTS Request to Send  
C RX Data out of radio or crypto device  
D TX Fill data into radio or crypto device  
E CTS Clear to Send  
F - -  
Help wanted
At present, not much is known about DS-101, EKMS-603 and the underlying data structure. You can help us to expand this page by providing additional information about transfer devices that use DS-101, supported radios, supported encryption devices, and the underlying data structure.

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Crypto Museum. Created: Sunday 11 February 2018. Last changed: Sunday, 11 February 2018 - 14:06 CET.
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