APX Voice Scrambling?

[slobonmycob]

When monitoring another agency that uses APX8000/8500 radios, I notice that some of their transmissions come through scrambled. Is this an option? The agency I work for wasn't aware that it is when I asked out tech.
If so, how does it work? Is it an option that has to be in the Flashcode??

 

[WB9YBM]

Several years ago I heard that there are three levels of encryption:

1.) civilian versions that involve some type of inversion technology (also the least secure type);
2.) mid-security level (may not be for civilian use), and;
3.( high level security reserved (as far a I know) for government comm.

Things have most likely developed a bit further since I found out the aforementioned.

 

[KevinC]

Define "scrambled". Is this analog or digital?

The APX line does encryption, but has no factory option for "scrambled" audio.

Encryption algorithms are loaded in via a KVL (AES256, DES-OFB, DES-XL and DVP). ADP can be either HW or SW, depending on how the radio is programmed. Flashcode options will give you multi-key capability, but the algo still needs to be loaded.

 

[GTR8000]

Analog? P25? Be more specific and you'll get a more specific answer. Most APX subscribers came with single key ADP 40-bit encryption for free, however that changed a few years ago, and now ADP must be specified when ordering an APX subscriber (it's still a no-charge option I believe). There are stronger forms of encryption available, notably AES-256, which is not cheap. ADP and AES apply to P25 only, not analog. Trying to use "voice scrambling" on analog is generally a waste of time.

 

[slobonmycob]

Analog? P25? Be more specific and you'll get a more specific answer. Most APX subscribers came with single key ADP 40-bit encryption for free, however that changed a few years ago, and now ADP must be specified when ordering an APX subscriber (it's still a no-charge option I believe). There are stronger forms of encryption available, notably AES-256, which is not cheap. ADP and AES apply to P25 only, not analog. Trying to use "voice scrambling" on analog is generally a waste of time.

Sorry, P25 TDMA Motorola. And yes I'm aware of other forms of encryption, I have the option to turn it on when transmitting sensitive information... but whenever I do that you don't hear anything. I know this agency has encryption capabilities like my agency does so I'm not sure really what or how or why they can scramble their voice.

 

[slobonmycob]

The APX line does encryption, but has no factory option for "scrambled" audio.

What's weird is when listening on my portable via NAS, I just don't hear anything. But on the MCC7500 and my uniden it's coming through scrambled.

 

[KevinC]

What's weird is when listening on my portable via NAS, I just don't hear anything. But on the MCC7500 and my uniden it's coming through scrambled.

Ah! The VPM doesn't have the keys and/or algorithm loaded. The scanner is just a scanner.

 

[slobonmycob]

Ah! The VPM doesn't have the keys and/or algorithm loaded. The scanner is just a scanner.

But other encrypted channels just don't come through at all which is the same with the scanner

 

[KevinC]

But other encrypted channels just don't come through at all which is the same with the scanner

I can't speak for your scanner, scanners do weird things with encryption.

I'd have to think about the console..my guess would be whatever algo they use your VPM doesn't have. I would bet it's ADP since scanners have a hard time with ADP sometimes (or at least mine do).

 

[xmo]

This can happen where agencies within a region have not coordinated secure CKR's.

Radios and consoles use the CKR to identify the correct key to use for each encrypted call.

If you have duplicated CKR's with different key variables, the result can be gobbledygook.

 

[chrismol1]

This can happen where agencies within a region have not coordinated secure CKR's.

Radios and consoles use the CKR to identify the correct key to use for each encrypted call.

If you have duplicated CKR's with different key variables, the result can be gobbledygook.

Yup isn't that the case, where the KEY ID is the same but if the KEY itself is different will unmute to un-intelligible audio. On another note, when scanning voice channels if Selective Squelch is selected and you put in the NAC for each channel, it will ignore encrypted transmissions with the wrong key id leaving only unencrypted voice to unmute

 

[slobonmycob]

Radios and consoles use the CKR to identify the correct key to use for each encrypted call.

How can I confirm the correct key is being used?

 

[slobonmycob]

I'd have to think about the console..my guess would be whatever algo they use your VPM doesn't have. I would bet it's ADP since scanners have a hard time with ADP sometimes (or at least mine do).

I did some research on this and it only left Me with more questions. The agency with the scrambled audio is NIMS compliant. I know this because it was a requirement for federal grants that we receive. ADP is not NIMS compliant. This agency (as well as my own) is ANAL about being NIMS compliant. So I don’t understand how they could be approved for grants then?

 

[KevinC]

I would suggest contacting whomever maintains your system and asking them for support. A hobby radio forum isn't the proper place to troubleshoot an issue like this.

 

[mmckenna]

I did some research on this and it only left Me with more questions. The agency with the scrambled audio is NIMS compliant. I know this because it was a requirement for federal grants that we receive. ADP is not NIMS compliant. This agency (as well as my own) is ANAL about being NIMS compliant. So I don’t understand how they could be approved for grants then?

NIMS or FBI/DOJ FIPS compliant?

If they are a public safety agency and are buying radios using federal grants, then they are likely using P25 with AES-256 FIPS compliant encryption. That's completely different than 'scrambling', which often is used to describe low end stuff used on analog systems.

I agree with Kevin, if the agency is using AES-256, then the ONLY way to do this is with the cooperation of your agency. You'll need them to load the encryption key into your radio with the KVL or whatever they are using for their key management/loading. This sort of stuff you are not going to get from a hobby radio site. Any radio that goes on a public safety radio system and required encryption is going to need the OK and assistance from the agency. Adding radios without their OK violates a couple of FCC Part 90 rules.

 

[GlobalNorth]

How can I confirm the correct key is being used?

The short answer is that you can't.

 

[KevinC]

I think we've provided the proper direction the OP needs to proceed. Closing.