DMR vs P25 - Encryption standards and software vs hardware encryption

[UglyViking]

Hey all,

I'm really hoping this doesn't turn into a flame war or anything, I'm just trying to better understand the key differences in implementation.

Question
I'm aware that companies like Anytone, Hytera, Motorola, etc. offer encryption in their DMR radios, and I know that Anytone and Hytera specifically offer AES-256 encryption. Meanwhile, P25 radios from EFJ, Motorola, etc. also offer AES-256 encryption. I can only speak direct experience to older EFJ 5100/5300 series radios and the XTS line requiring keyloaders in order to encrypt them, and that the encryption is done on the hardware via a custom board. My question is, how is AES-256 done on the DMR side? Are there crypto boards on DMR radios? Do modern P25 radios no longer have crypto boards and they have unified the design?

I know that P25 radios are pretty hardened against physical attacks so that, as an example, if a police officer loses a radio someone can't just pull they keys and listen in. I'm curious how DMR handles something like this? I also realize that you can easily avoid any real issue here by simply rotating keys in a semi-consistent manner, and doing a forced key change upon a radio getting lost, so this isn't really for any real application and more so just pure interest at this point from some of the conversations I've read online.

If anyone can point me to anything on the subject it would be awesome, as I'm struggling to find any real data out there.

 

[tweiss3]

Modern P25 radios do require an encryption board, some are standard, some are optional equipment. Currently KVL loading is the "standard" but some offer software loading of the encryption boards, but it is typically frowned upon by most large P25 systems.,

DMR encryption is software loaded only, and does not require a separate encryption board.

 

[KE4ZNR]

Modern P25 radios do require an encryption board, some are standard, some are optional equipment. Currently KVL loading is the "standard" but some offer software loading of the encryption boards, but it is typically frowned upon by most large P25 systems.,

DMR encryption is software loaded only, and does not require a separate encryption board.

Yep. As a general rule of thumb AES encryption in Motorola Mid/High Tier radios is handled in the MACE chip in the radio itself. You can learn more about the Motorola Advanced Crypto Engine (MACE) in the following pdf:
https://csrc.nist.gov/CSRC/media/pr...ram/documents/security-policies/140sp3948.pdf

 

[UglyViking]

Modern P25 radios do require an encryption board, some are standard, some are optional equipment. Currently KVL loading is the "standard" but some offer software loading of the encryption boards, but it is typically frowned upon by most large P25 systems.,

DMR encryption is software loaded only, and does not require a separate encryption board.

Don't some large scale P25 systems leverage OTA rekey? I'd assume that is technically software as middle layer between the crypto chip and the OTA update?

My main assumption here is that the KVL and crypto chip offer two main advantages.

1. Only authorized users can keyload, as KVLs are a physical interface that are highly guarded, vs software which is much easier to hand out.
2. The crypto chip is much more resilient to physical attacks since the I/O for the chips are relatively small (power, load/read keys, status from test, etc.)

Does that sound about right?

Yep. As a general rule of thumb AES encryption in Motorola Mid/High Tier radios is handled in the MACE chip in the radio itself. You can learn more about the Motorola Advanced Crypto Engine (MACE) in the following pdf:
https://csrc.nist.gov/CSRC/media/pr...ram/documents/security-policies/140sp3948.pdf

Thanks for sharing, that's an interesting flip through for sure, I'll have to dig into it more. Seems like that is the older version of FIPS as they are now on 140-3 I believe? Either way, it's a nice overview of the chip and it's architecture at a high level.

Are you aware of anything from any DMR handset? It would be interesting to compare/contrast an anytone/hytera with that moto sheet.

 

[N4DES]

In order for a radio living on a system that has OTAR capabilities to re-key the initial load of the UKEK is required with a keyloader.

https://www.project25.org/images/stories/ptig/docs/Tait%20P25%20Encryption_APCOUS_Jul10.pdf