P25 keyfill device electrical interface

[mr.syntrx]

Before I find my credit card and grab a copy of TIA-102.AACD, is there anything electronically specific about the keyfill device interface that would make it difficult to implement with standard computer hardware? I assume it's just some kind of serial interface?

Thanks

[Wowbagger]

It's just an open collector, TTL level, common data signal - serial, both sides pull it low, one side supplies +5V through a resistor.

Are you going to try to build your own keyfill device? If so, you should know - there are 2 protocols in use. One is fully documented in the APCO standards and is freely available.

The other is Motorola proprietary and prying documentation out of Motorola is VERY hard, involves an NDA, and what you get is, shall we say, somewhat thin.

[MattSR]

Are you going to try to build your own keyfill device?

Lets say someone wants to build such a device based on a P25 OTAR/KFD spec that is freely available (ie NOT the ASN protocol)

Would such a device be infringing Motorolas patents such as http://www.freepatentsonline.com/20050220307.html

[txshooter]

has anyone else looked at the EFJ Keyloader based on a widely available PDA.......

[MattSR]

No, but id like to have a look. Do you have a link?

[MattSR]

found it.

http://www.efjohnson.com/products/smakeyloader.asp

[TXCAP]

The SMA works pretty well, Keyloads DES, DES-OFB, AES & OTAR Shadow Keys allows the reading of keysets (NOT THE ACTUAL KEY STRING) or types of keys loaded & their respective PIDs & algo's ....... Will also work on XTS portables. I am also going to attempt to make a Mobile cable for Moto's.. just need to get a few parts in.