Security can a key aspect of public-safety communications, but Project 25 (P25) system managers should establish policies to help ensure that encryption is used only when necessary, P25 network veterans said during a best-practices workshop in Washington, D.C., sponsored by Tait Communications.

While encrypted communications are vital for some specialized personnel—for example, members of SWAT teams, bomb squads and narcotics operations—it is not advisable to use encryption for all public-safety communications, according to Craig Jorgensen, former president of the P25 steering committee.

“Encryption was never intended to be a ubiquitous tool that everybody has; if everybody’s got it, there no longer is the security element that you want,” Jorgensen said. “Encryption was intended for high-security risks, not just day-to-day traffic. The cost of encryption is not only the economic costs but the cost of the spectrum that you’re using to perform the encryption, and there’s still a minor degradation [of voice quality] in encryption.

“So, encryption shouldn’t be dealt with as an option, like a green light or a blue light. [You should look at] why I need it, how much am I willing to pay for it, and who really needs it.”

Another issue with encryption is that it is not always possible to coordinate the security feature with other jurisdictions that may provide help during an emergency, according to Allen Holder, director of Lincoln County 911 Center in West Virginia.

“If you encrypt too much, you may make your network so secure that you lose the benefit of interoperability,” Holder said.

This sentiment was echoed by several participants, with some noting that they have policies against using encryption on mutual-aid channels.

There was a general consensus that public-works and public-service employees do not need encryption capabilities on their radios, but encryption usage for non-specialized public-safety organizations varied significantly between the participants.

“I put encryption in all my equipment and components in the statewide system, because I was told that everything had to be encrypted in 1999,” said Paul Leary, chief of communications for the state of New Hampshire. “Fourteen years later, I have yet to have to use an encrypted channel in my department.

“We put too much into the idea of encryption. On the data side, we know we’re going to have to have that encrypted—they want us to have that. With voice, my biggest fear is with interoperability and people getting into trunked systems without a gateway set up, or [they] don’t have the agreed interoperability channels loaded into their radios.”

Flexibility is necessary, according to Mike Ward of Beaufort County Communications in South Carolina.

“In my opinion, it really depends on how the agency wants to operate and at what level,” Ward said. “Our sheriff said, ‘All of my stuff is going to be encrypted; that’s how it’s going to be,’ and the rest of law enforcement followed. The fire department said it wanted half and half.”

For those departments that do use encrypted communications, Jorgensen emphasized the importance of using standardized encryption instead of proprietary solutions that may cost less initially but can create long-term problems.

“When we talked about standardized encryption, we talked about it for a specific purpose, and that was to ensure that, if Agency A and Agency B are encrypted, they can communicate,” Jorgensen said. “When you buy a proprietary encryption, you do two things. The first thing you do is you lock your system into that encryption mode. The second thing you do is you prevent other vendors from using that encryption.

 “What you’re really doing is saying that, ‘I’m not going to have interoperability in the encryption mode, unless I buy all my stuff from that vendor’—whoever that vendor is, because they all sell proprietary encryption.”

Of course, using encryption requires all participating users to have the appropriate encryption keys in their radios. Theoretically, this function can be done via over-the-air rekeying (OTAR), but workshop participants noted several logistical issues with that approach. Ward said he used a form of OTAR in the military, but radios that were taken out of network range or were turned off sometimes were missed, which created additional maintenance work.

“I’m not a big fan [of OTAR],” Ward said. “Over 18-odd years, I’ve developed the attitude of, ‘If I have to change the key, it’s going to be a physical change. We’re going to connect the machine to each individual device, because I still end up doing it anyway.’

“That’s my personal opinion on it. We don’t use it on our system at this time.”

Holder said that handling encryption rekeying in house also allows the radio shop to assess the general condition of radios on a regular basis.

“We always end up doing a certain amount of antenna changes, battery upgrades [and] fixing clips and things, when we do our programming,” Holder said.