P25 CAP Officials Prioritize Nonstandard Encryption, TDMA Testing
Tuesday, February 28, 2017 | Comments
Addressing nonstandard encryption and its negative effects on public-safety interoperability is a top task for the Project 25 (P25) Compliance Assessment Program (CAP), according to the chairman of the CAP advisory panel (AP) and a Department of Homeland Security (DHS) official.

A Compliance Assessment Bulletin (CAB) “to stop the practice of manufacturers providing subscriber units with a non-P25 standard encryption without also including P25 standard AES 256 encryption” was released in January, and DHS requested comment. Sridhar Kowdley, program manager of the P25 CAP for DHS Science and Technology (S&T) Directorate, said program officials are adjudicating the comments, and a final version of the CAB will be posted on the CAP website in coming weeks.

The CAB requires all P25 radios with encryption to include Advanced Encryption Standard (AES) 256 as a baseline. If a radio has proprietary encryption, AES 256 must be included as well and used during mutual-aid situations if encryption is needed.

“We leveraged this off existing SAFECOM guidance,” Kowdley said. “SAFECOM has said if you are going to produce a radio and you want to include a nonstandard feature when there is a standard feature available, you must include the standard feature as well. We are enforcing the guidance.”

“The problem we have with encryption is there is a nonstandard encryption being offered by some manufacturers that is making interoperability for those choosing encryption nonstandard again,” said Chief Gerry Reardon, chairman of the AP. “The AP believes that is the biggest impediment to interoperability right now.”

The 10-member AP, formed in late 2015, includes P25 users from around the country and federal officials.

The AP is also working on a CAB to allow CAP testing for P25 Phase 2 TDMA equipment. TDMA equipment has been on the market for years, but the parameters for testing the equipment under the CAP program haven’t been established until now. The TDMA CAB is also a priority but will follow the nonstandard encryption CAB, Kowdley said.

A third CAB that likely will take longer to implement will address testing the Console Subsystem Interface (CSSI) and Inter RF Subsystem Interface (ISSI). The biggest challenges for the interfaces are a lack of accredited laboratories to perform the testing, and the tests are expensive because a lab needs the core infrastructure for three different vendors.

“The issue is the business case and the affordability and viability for these labs to host that work,” Kowdley said. “We are looking for ways to do that. We’ve asked industry for creative ways to test the ISSI and CSSI, and we will see if we can vet that through the P25 CAP program and implement it.”

During the latest AP meeting, a vendor demonstrated a software-based emulation tool that could potentially provide a virtual ISSI test. The AP is looking at other possibilities as well.

Another challenge is the slow process of reaccrediting the original eight P25 CAP laboratories. In 2013 DHS announced that the American Association for Laboratory Accreditation, ANSI-ASQ National Accreditation Board and International Accreditation New Zealand joined its P25 CAP laboratory accreditation efforts. Kowdley said two of the eight labs have been reaccredited, and he is hopeful that the remaining labs will be completed in coming months.

Another push by the CAP AP is educating users and highlighting the value of the CAP program to public-safety interoperability. SAFECOM is looking to change its grant guidance to require any public-safety communications equipment purchased with federal money to meet P25 CAP certification. “We don’t want people buying equipment that isn’t interoperable with grant money,” said Reardon, who is also chairman of SAFECOM.

Reardon said other digital technologies are less expensive than P25, and public-safety officials “have to be able to justify a public-safety-grade radio that costs more.”

“We need to make sure there is an ironclad standard that meets state, local and federal guidelines,” Reardon said. “We are making sure public safety is interoperable, and we don’t want to go down another path of technology that sets us back.”

Public-safety officials should look to buy P25 CAP equipment because they will have a higher confidence and it has gone through regimented testing, Kowdley said.

With a long list of to-do items, the newly formed P25 AP is busy. “We have a lot of work to do, and we’re trying to bite off a lot of this work as we go, but we want to be judicious in getting it done,” Reardon said.

The list of P25 CAP-approved equipment is here.

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On 3/2/17, Richard Massie said:
This is a positive step in the right direction for proponents and supporters of interoperability and security. The CAP AP and DHS are to be congratulated for their efforts. P25 and LMR in general are still very relevant and important. Thanks MissionCritical Communications for remembering your roots and continuing to report on LMR.

On 3/2/17, Jon Awalt said:
How about working on P25 conventional TDMA? It is amazing that in 2017 we still have to scratch for another frequency for departments when they are P25 conventional but can't take advantage of TDMA in a P25 radio unless it's trunking. It's like something or someone is purposely blocking P25 conventional TDMA.

On 3/1/17, Mike Christie said:
Can we get a clarification on mutual aid? Are you advocating the use of encryption on the DHS mutual aid repeaters 800, 700, etc.? Based on what I just read, there maybe some confusion. I would think these should remain unencrypted, but it needs to be clarified.
Thanks, Mike
From Chief Reardon: My comments on mutual aid were based on a broad use. Many localities use local frequencies and possibly local mutual-aid channels. We are not advocating the use of encryption, and especially on national interoperability channels. However we know that under large selective operations, encryption plays a necessary role, which is becoming more prevalent. Having interoperable communications requires compatibility, hence P25 requirements and standards to be sure that all responders can communicate. The encryption CAB seeks to be sure that when encryption is required that we still have a common platform using AES 256. The encrypted communications would be on those frequencies where it is allowed for such use.

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