6 ms·

"Why (special agent) Johnny (still) Can’t Encrypt" https://csrc.nist.gov/CSRC/media/Events/ISPAB-OCTOBER-2012-MEETING/documents/ispab_oct2012_mblaze_p25-securit

"Why (special agent) Johnny (still) Can’t Encrypt" https://csrc.nist.gov/CSRC/media/Events/ISPAB-OCTOBER-2012-MEETING/documents/ispab_oct2012_mblaze_p25-security-analysis.pdf https://csrc.nist.gov/CSRC/media/Events/ISPAB-OCTOBER-2012-M... (Warning, slightly terrifying paper) P25 is very vulnerable to jamming, decrypting encrypted traffic, traffic analysis, and geo tracking of individual radios. - Because of the design of P25, commonly used in America, if you enable encryption, a tiny bit of noise in the signal makes it unusable. One problem is that there are separate error correction codes for different parts of the packet, and very few error correction bits were allocated for the important encryption bits. To get around this, sometimes just the dispatchers will have encryption on, since those packets are traveling over fiber to the transmission towers, where they are broadcast at high power levels. The other direction, personal radio to repeater tower, is almost never encrypted because of the much lower power of the personal radios. P25 has some nice features - our local area has perhaps a hundred different public safety organizations, all of which can talk to each other at any time, and often coordinate for any major incident. But security is not one of them.

rsync 9y ago
"P25 has some nice features ... but security is not one of them." And that is just fine. Police and firefighters/medics[1] are civilians and are in their role to serve civilians at the pleasure of civilians. There is no need for secret comms and, in fact, it is often quite valuable for the public at large to have visibility into their operations in real time. There is no need to encrypt public safety radio comms and you should be quite suspicious of anyone who claims that there is. Those radios belong to you. The frequencies belong to you. The people who use them are your own servants. [1] I am a firefighter/medic in the SFBA.
- tbabb 9y ago
  Agree, it is probably good for police / fire / EMT etc. to be open. However, the linked talk above notes that the researchers accidentally discovered that some "sensitive tactical law enforcement operations" were unwittingly operating in cleartext, and divulged to the open air "names and/or identifying features of targets and confidential informants, their locations, descriptions of undercover agents, [...] plans for forthcoming takedowns and operations," and a few other things you probably don't want to widely announce. It also notes that radio locations could be easily discovered, even if they're not communicating. Bad guys could therefore build a map of possibly-federal-agents in the city, and learn things they're not supposed to know even if they can't hear what's being discussed. Again, PD/Fire/EMT are great to have open and mutually communicating. But there are (life and death) reasons why you might really need a secure channel in other cases.
  - dsfyu404ed 9y ago
    >However, the linked talk above notes that the researchers accidentally discovered that some "sensitive tactical law enforcement operations" were unwittingly operating in cleartext, and divulged to the open air "names and/or identifying features of targets and confidential informants, their locations, descriptions of undercover agents, [...] plans for forthcoming takedowns and operations," and a few other things you probably don't want to widely announce. We expect block headed 18yo infantrymen not to send sensitive information over insecure channels. I don't think asking the same from our public servants is unreasonable.
    - tbabb 9y ago
      Then we agree that secure channels should exist?
  - netsharc 9y ago
    AFAIK in Europe they have full-encryption. But the presence of encrypted traffic in the reserved airwaves near you means there are cops/fire/ambulance nearby. I remember reading about someone building a cop radar by exploiting this property! There are false positives (e.g. you're speeding down the autobahn, and there's an ambulance in a town you're passing through), but it's probably good enough...
- deleted 9y ago
  [deleted]
- noir_lord 9y ago
  In the UK the police moved to encrypted radios quite a while ago and it's an offense under a 2006 act to listen to them even if you could.
  - guelo 9y ago
    I've been surprised with how authoritarian the UK has turned lately.
- CamperBob2 9y ago
  There is no need for secret comms Most common thing heard on a police scanner around here: "Call me on my cell."
blantonl 9y ago
Because of the design of P25, commonly used in America, if you enable encryption, a tiny bit of noise in the signal makes it unusable. That is incorrect. There is no difference in voice quality or degradation in quality of service between an encrypted P25 signal and an unencrypted one. An analogy would be like claiming that there is a difference in quality of service between http and https.
- danielvf 9y ago
  There's no voice quality difference, if the packet goes through, that's true. The problem is that without encryption, P25 packets can handle a bit of radio noise and still be error corrected into usability. With encryption, in practice, certain bits get altered that cannot be error corrected and the packet cannot be decoded. P25 error correction ability is not evenly across the entire packet. HTTP and HTTPS are riding on top of TCP, which mostly guarantees in order bytes, the correct bytes, and no missing bytes. If you loose the guarantees of TCP, and allow say 1 out of 2000 bytes to be altered randomly, HTTP would still mostly work, and HTTPS would be dead as a doornail.
  - blantonl 9y ago
    Again, that is incorrect. Error correction is applied after encryption via 2.8kbs /sec of forward error correction paired with 2.4kbs /sec of data signaling. And the IMBE vocoder also provides it's own error correction. The signaling, voice and error correction is then formatted into P25 speech frames. A transmission starts with a header data unit, identifying the destination of the call and if encryption was used or not. It then continues with a series of logical link data units (LDUs), that carry the digital speech. The LDUs also repeat the signaling information and the synchronization sequence, so radios can join the call late, or reenter if they drop out due to bad RF coverage and then come back into the call. The call ends with a terminator data unit, indicating that the PTT’s been released, and this is the end of the call. To get around this, sometimes just the dispatchers will have encryption on, since those packets are traveling over fiber to the transmission towers, where they are broadcast at high power levels. The other direction, personal radio to repeater tower, is almost never encrypted because of the much lower power of the personal radios. This is also not correct. Encryption can either be manually turned on or off by the individual user (radio) and/or the dispatcher, or encryption can be "strapped" to a talkgroup in cases where full time encryption is used. THe scenario you describe is all based on the user's choice, not an operational need due to power levels.
avs733 9y ago
Here is the video of a very similar talk those authors gave at HOPE five years ago: https://www.youtube.com/watch?v=7or-_gT8TWU https://www.youtube.com/watch?v=7or-_gT8TWU one of my favorite con talks in a long time. Highly entertaining and hugely informational.

rsync 9y ago

"P25 has some nice features ... but security is not one of them." And that is just fine. Police and firefighters/medics[1] are civilians and are in their role to serve civilians at the pleasure of civilians. There is no need for secret comms and, in fact, it is often quite valuable for the public at large to have visibility into their operations in real time. There is no need to encrypt public safety radio comms and you should be quite suspicious of anyone who claims that there is. Those radios belong to you. The frequencies belong to you. The people who use them are your own servants. [1] I am a firefighter/medic in the SFBA.

tbabb 9y ago
Agree, it is probably good for police / fire / EMT etc. to be open. However, the linked talk above notes that the researchers accidentally discovered that some "sensitive tactical law enforcement operations" were unwittingly operating in cleartext, and divulged to the open air "names and/or identifying features of targets and confidential informants, their locations, descriptions of undercover agents, [...] plans for forthcoming takedowns and operations," and a few other things you probably don't want to widely announce. It also notes that radio locations could be easily discovered, even if they're not communicating. Bad guys could therefore build a map of possibly-federal-agents in the city, and learn things they're not supposed to know even if they can't hear what's being discussed. Again, PD/Fire/EMT are great to have open and mutually communicating. But there are (life and death) reasons why you might really need a secure channel in other cases.
- dsfyu404ed 9y ago
  >However, the linked talk above notes that the researchers accidentally discovered that some "sensitive tactical law enforcement operations" were unwittingly operating in cleartext, and divulged to the open air "names and/or identifying features of targets and confidential informants, their locations, descriptions of undercover agents, [...] plans for forthcoming takedowns and operations," and a few other things you probably don't want to widely announce. We expect block headed 18yo infantrymen not to send sensitive information over insecure channels. I don't think asking the same from our public servants is unreasonable.
  - tbabb 9y ago
    Then we agree that secure channels should exist?
- netsharc 9y ago
  AFAIK in Europe they have full-encryption. But the presence of encrypted traffic in the reserved airwaves near you means there are cops/fire/ambulance nearby. I remember reading about someone building a cop radar by exploiting this property! There are false positives (e.g. you're speeding down the autobahn, and there's an ambulance in a town you're passing through), but it's probably good enough...
deleted 9y ago
[deleted]
noir_lord 9y ago
In the UK the police moved to encrypted radios quite a while ago and it's an offense under a 2006 act to listen to them even if you could.
- guelo 9y ago
  I've been surprised with how authoritarian the UK has turned lately.
CamperBob2 9y ago
There is no need for secret comms Most common thing heard on a police scanner around here: "Call me on my cell."

blantonl 9y ago

Because of the design of P25, commonly used in America, if you enable encryption, a tiny bit of noise in the signal makes it unusable. That is incorrect. There is no difference in voice quality or degradation in quality of service between an encrypted P25 signal and an unencrypted one. An analogy would be like claiming that there is a difference in quality of service between http and https.

danielvf 9y ago
There's no voice quality difference, if the packet goes through, that's true. The problem is that without encryption, P25 packets can handle a bit of radio noise and still be error corrected into usability. With encryption, in practice, certain bits get altered that cannot be error corrected and the packet cannot be decoded. P25 error correction ability is not evenly across the entire packet. HTTP and HTTPS are riding on top of TCP, which mostly guarantees in order bytes, the correct bytes, and no missing bytes. If you loose the guarantees of TCP, and allow say 1 out of 2000 bytes to be altered randomly, HTTP would still mostly work, and HTTPS would be dead as a doornail.
- blantonl 9y ago
  Again, that is incorrect. Error correction is applied after encryption via 2.8kbs /sec of forward error correction paired with 2.4kbs /sec of data signaling. And the IMBE vocoder also provides it's own error correction. The signaling, voice and error correction is then formatted into P25 speech frames. A transmission starts with a header data unit, identifying the destination of the call and if encryption was used or not. It then continues with a series of logical link data units (LDUs), that carry the digital speech. The LDUs also repeat the signaling information and the synchronization sequence, so radios can join the call late, or reenter if they drop out due to bad RF coverage and then come back into the call. The call ends with a terminator data unit, indicating that the PTT’s been released, and this is the end of the call. To get around this, sometimes just the dispatchers will have encryption on, since those packets are traveling over fiber to the transmission towers, where they are broadcast at high power levels. The other direction, personal radio to repeater tower, is almost never encrypted because of the much lower power of the personal radios. This is also not correct. Encryption can either be manually turned on or off by the individual user (radio) and/or the dispatcher, or encryption can be "strapped" to a talkgroup in cases where full time encryption is used. THe scenario you describe is all based on the user's choice, not an operational need due to power levels.

avs733 9y ago

Here is the video of a very similar talk those authors gave at HOPE five years ago: https://www.youtube.com/watch?v=7or-_gT8TWU https://www.youtube.com/watch?v=7or-_gT8TWU one of my favorite con talks in a long time. Highly entertaining and hugely informational.