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Communications Australia Encryption Security Wireless Networking Technology

Security Researchers Crack APCO P25 Encryption 37

Posted by timothy
from the breaker-breaker-this-is-roscoe-p-coltrane dept.
An anonymous reader writes "Two Australian security researchers, Stephen Glass and Matt Robert, have published a paper that details flaws in the encryption implementation (PDF) in the APCO Project 25 digital radio standard, used by emergency services and police departments world-wide. The paper details flaws in the DES-OFB and ADP encryption that enable the encryption key to be recovered by traditional brute force key searching. Also detailed is a DoS attack that makes use of unauthenticated radio inhibit mechanism. The research is part of the OP25 project, which uses GNUradio to implement a P25 stack using software defined radio. With this solution in place, the researchers were able to do detailed analysis of the traffic coming from various radio systems and to transmit and receive to P25 radios in their lab."
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Security Researchers Crack APCO P25 Encryption

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  • But they cost $1700! No thank you. How many people are even using them at that price?

    • Yeah $1700 is a lot for a drug dealer wanting to know the cops are coming for him.
    • by nten (709128) on Saturday September 10, 2011 @12:50PM (#37362870)

      Comparable equipment has traditionally cost in the 10s of thousands. Only in the last two or three years has it been in the home hobbyist range. Granted its not cheap, but its about the same as a good gaming rig. And its far less than car or shooting enthusiasts tend to spend. That said, the $1700 only includes the motherboard (fpga and ADC/DAC) and enclosure, not the receiver. The receivers range from a hundred to almost five hundred depending on what you need. Same API to control all of them though. If you want to mess with the fpga instead of doing it all on the PC you probably want the slightly cheaper motherboard so you can use the free xilinx webpack ise instead of the crazy expensive one.

      Comblocks also has a nice SDR offering but getting it to the PC at a decent speed is still around $800 at least, and I don't know how clean the software interface is.

      Slapping an fpga and highspeed ADC onto a custom PCB is easy enough, you can get such things from knjn prebuilt, but you really need gigabit ethernet or faster to do software processing on significant bandwidth and those sorts of interfaces tend to need five and six layer PCBs which aren't DIY and jack up the price. Perhaps the USB3 interfaces will be more hobby friendly. You still need a software controlled wideband receiver too, maybe heathkit will step up on that one.

      All in all, the USRP is reasonable, though its been getting more expensive due to more features, and NI buying them might be involved too, NI doesn't tend to make cheap stuff.

      • by citizenr (871508)

        Slapping an fpga and highspeed ADC onto a custom PCB is easy enough, you can get such things from knjn prebuilt, but you really need gigabit ethernet or faster to do software processing on significant bandwidth and those sorts of interfaces tend to need five and six layer PCBs which aren't DIY and jack up the price. Perhaps the USB3 interfaces will be more hobby friendly. You still need a software controlled wideband receiver too, maybe heathkit will step up on that one.

        All in all, the USRP is reasonable, though its been getting more expensive due to more features, and NI buying them might be involved too, NI doesn't tend to make cheap stuff.

        Cypress already announced EZ-USB 3, if its anything like FX2LP implementing solutions will be a breeze
        http://www.cypress.com/?rID=51181 [cypress.com]

    • by Anonymous Coward

      A local news service would. Typically the encrypted channels on many city police systems are the "command nets." The command nets are typically captains and above. The use of encrypted systems by "officers" generally would be limited to ERT (A.K.A. SWAT), Major Narcotics, OPR (A.K.A. internal affairs) outside of those groups most the others wouldn't care. Besides most criminals could not afford the current scanners that can grab the clear transmissions now anyway.

    • by Anonymous Coward

      FUNcube Dongle [funcubedongle.com]- A radio thats out of this world!

      64MHz to 1,700MHz Software Defined Radio

      funcube.org.uk [funcube.org.uk]

      Quoth shoc.ch [www.shoc.ch] :

      "The FUNcube Dongle was successfully tested with W-CODE. It worked perfect with POCSAG, TETRA, APCO-25-DMR, dPMR, INMARSAT-C, INMARSAT-AERO... No drivers required! Device drivers are already included in your operating system - Windows, Linux or Mac OSX, 32 or 64 bit.
      You can order this low cost 64MHz to 1,700MHz Software Defined Radio for 99" quid

    • As a ham radio operator, I know a few guys that spend 2 to 3 grand on P25 Mototola radios. I can picture a couple of them now, reading this paper over very carefully :)

  • The article seems to cover two things here: - Brute force "vulnerability". - Unauthenticated DoS. The former seems to be the focus, but it is hardly the most shocking of the two. You can always do a brute force key search with any captured data, and one would assume that, being DES, it is at least 56 bits. The unauthenticated DoS, however, presents a serious flaw.
    • I would have thought that any wireless communication device can be easily DoSed by a normal jammer. No specific knowledge of the protocol needed.

  • by thue (121682) on Saturday September 10, 2011 @12:48PM (#37362858) Homepage

    > Once a radio has been stunned by the receipt of an inhibit command the standard requires that it remains in-operational and unresponsive to the operator console or device programming interface until it receives an “uninhibit” XFC on the frequency it received the inhibit. The attack exploits the lack of any guarantee of authenticity for the frame Inhibit/Uninhibit types. [...] Note that the XFC message payload may be sent either encrypted (P=1) or un-encrypted (P=0).

    Not a desirable property in a supposedly secure crypto system!

    • by Sduic (805226)

      Based on the article, it seems the system is often restricted to a small common subset of security/authentication due to needing to maintain interoperability with legacy elements (e.g. DES-OFB encryption must be available where used, but others are optional).

      In other words, they (may not be able to) keep a secret because the other stuff doesn't understand HOW to.

      As to how effective their security would be otherwise, I couldn't say, although apparently authentication is a major problem that would need attent

      • by thue (121682)

        Other parts of the article talks about security features being disabled because of interoperability. As I read the part of the article I quoted, there simply isn't any specification in the protocol to authenticate inhibit command, so this specific problem is not because of interoperability.

        • The interoperability referred to is whether the inhibit request is sent encrypted or in the clear, not whether or not it had authentication. If you have the wrong crypto type, you can just fall back into clear mode for "interoperability".
             

    • Hah yeah.

  • http://it.slashdot.org/story/11/08/10/2113246/Feds-Radios-Have-Significant-Security-Flaws [slashdot.org]

    APCO 25 doesn't seem to be very well thought through. Easily jammed at multiple levels and vulnerable in many ways.

    --Paul

    • Re: (Score:3, Insightful)

      P25 wasn't originally designed with security in mind. It was designed as a standardized digital replacement for the mess of incompatible digital and analog trunking systems that had grown up in the 80s and 90s. In its basic, as-designed, unencrypted mode, it works well. It's only when local PDs and FDs decide to try and lock out scanner users (nominally to keep criminals from listening, but more often to keep away TV news crews) by means of ill-conceived encryption addons that things fall apart.

  • It's pretty much only used in America. Everyone else uses TETRA, or if they don't want trunking DMR or iDAS.

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