I want to know if my BLE 5 (low energy, not "typical"/core bluetooth) embedded system uses (preferably asymmetric) encryption, if encrypted at all.
I'm using this ble module that is communicating with an SOC. My SOC is capable of encryption but the FAE of the BLE module product couldn't come up with any useful information.
My program doesn't appear to have a bonding/pairing process, but I could be wrong since I did not take a closer look at the HAL layer program.
My question is, does BLE 5 require encryption?
If not, how do I find out if my connection is encrypted or not, using methods other than sniffers? For example are there any steps which must be gone through to facilitate encryption, in which case I should check if these steps were skipped or not? (If skipped then surely my communication is in plain texts).
ETA: The target BLE module is based on nrf52832, don't know what BLE stack/softdevice they are using. My soc is STM32WB55 series, using a rather comprehensive BLE stack that supports most functions of which name I couldn't recall for the moment.
BLE does not require encryption for a connection to be made.
At first, every BLE connection starts in Security Mode 1, Level 1 which does not use any encryption at all. Every message will be sent in cleartext. To increase the security two devices have to "pair". Security keys are exchange during the pairing process. There are multiple different pairing methods with different requirements. Have a look at this article for a starting point.
The pairing process is usually not started manually but automatically as soon as a device tries to access a secured characteristic. If you are using a phone to access such a characteristic you will be prompted with a pairing request popup. Based on your description I would assume that your connection is currently not encrypted.
To enable encryption on your SoC please have a look at the function aci_gatt_add_char. This document (direct download link) refers to this function on page 55 and shows that it takes Security_Permissions as an argument. The next page states the possible options as:
0x00: ATTR_PERMISSION_NONE
0x01: Need authentication to read
0x02: Need authorization to read
0x04: Link should be encrypted to read
0x08: Need authentication to write
0x10: Need authorization to write
0x20: Link should be encrypted for write
Related
We have some characteristics that are marked bonded/encrypted and some that are unbonded. Obviously if we have two unbonded devices, communication over the unbonded characteristics will not be encrypted, but does that change once bonding has occurred? Once the two devices are bonded, are all communications encrypted (even those over unbonded characteristics)?
The whole link is either encrypted or not so either all data is encrypted or none.
When a Bluetooth stack supports "marking" a characteristic with a specific security level and the link does not currently meet the required security, it will try to take the required actions to make the link meet the required security level and then try again. That means either start encryption if the devices are already bonded, or initiate pairing.
Note that even if two devices are bonded and posses a shared encryption key, that doesn't necessarily mean that the link will automatically be encrypted when a connection starts since it's not mandatory to encrypt the link.
Eddystone-EID beacons transmit Ephemeral Identifiers which will be resolved by Google's Proximity Beacon API. This means one can not detect an Eddystone-EID beacon without an active internet connection. The approach is pretty new, so there is not much info on the internet.
Generation of ephemeral identifier and resolving mechanism is described in this paper provided by Google researchers. Here is the summary of the procedure: Eddystone-EID beacons encrypt the value from their embedded time counters with AES-128 using their key, while the key is unique identifier for each beacon. The result is the ephemeral id that's goning to be transmitted. Like every 512 secs, beacons recomputes their ephemeral ids. When an ephemeral id received by the receiver side, the resolver tries to find the key which provides correct decryption among known predefined keys. The found key corresponds to identification of the beacon.
I'm wondering whether it's possible to implement an offline resolving/decryption procedure according to given paper, that works with Eddystone-EIDs on the market. Instead of using a global resolver at the cloud, can we develop a local resolver which works with much less number of beacons?
If yes, is there any previous attempts or implementations etc?
What's your opinions on this topic?
Yes, it is theoretically possible to implement an EID resolver in Android or iOS code that does the calculations to see if an EID transmission comes from a known beacon transmitter.
The mobile device implementation would need to use compatible AES-128 encryption libraries and somehow store copies of the keys needed to do the resolution for each beacon.
When building a server-side resolver implementation for testing purposes, I considered building such a library. I also learned it is very tricky to get everything exactly right. Many AES libraries only provide partial functionality so are unusable.
It is also important to note that US export restrictions on encryption software will make putting apps that do this in the Apple AppStore and Google Play Store problematic.
I've been looking for BLE materials to get answer to this. But I could not get in any. Though practically/logically speaking, peripheral should decide I want to see if it is documented some where. Any links with this information will be very helpful.
On iOS, at least, if the peripheral specifies that encryption is required for a characteristic then iOS Central will initiate a pairing operation when access is attempted. If encryption isn't required then no pairing takes place - The central can just initiate a connection.
So, in summary -
The peripheral 'decides' if pairing is required through the definition of its characteristics.
The central manages the pairing process when required.
On "Just Works"; my understanding is that this is pairing where neither device can display a passkey, or allow the user to input one. It is NOT an unencrypted connections.
While your general iOS device can do both, many devices, such as an toothbrush handle, can't, but can still require "just works" pairing and bounding. This is also called unauthenticated pairing with encryption. It appears that iOS will prompt the user to accept a pairing request if the peripheral can't display a passkey.
Can someone point me to a doc or site with information about how to build the encrypted section(s) of a zigbee packet? I'm looking at the output of a zigbee sensor system and I can see where most of the 'data' packets are being produced but there is a section call NWK Payload that is encrypted. I've watched the whole sequence of the connection with the 'base station' and I don't see where any sort of encryption key is being passed.
This shows the section I'm referring to. The packet analyzer has figured out the rest.
Long term goal is to build these packets and use the sensors separately from the 'base station'. To do that I need to be able to replicate the whole communication cycle.
In Zigbee there is are two keys used for encryption: the Link Key and the Network Key. The Link Key is used during the network association process, and the Network Key is used to encrypt all traffic once the device is "associated" (also referred to as "joined") to the network.
If the device is HA (Home Automation), the security handshake goes something like:
Joining Device sends Association Request to the Trust Center (usually address 0x000)
Trust Center responds to joining device with a NWK Key packet. The contents of this packet are encrypted using the well know Home Automation Link Key.
You should be able to decrypt the NWK Key packet if you know the Link Key. I'm pretty sure I can't post the key (sorry), but you can probably find it online.
As for the actual encryption algorithm, that's defined in the main Zigbee Specification, which I believe you have to be a member to gain access too. There are a few open source Zigbee stacks though ZBoss and FreakZ.
You might also look at Wireshark, I believe they have a decent Zigbee packet decoder though I haven't used it personally.
We use here the Perytons sniffer (http://www.perytons.com).
They have an Add-On with which you can create, edit and transmit messages (in parallel of doing the capture). We also use the add-on for "constructing" the ZigBee packets and encrypt it based on what you need so you can consider using it for debugging your encryption process.
They have a 30 days free evaluation with some of the TG Add-On options enabled ;-).
Hope this helps.
I'm a young professional who's into embedded design, IT networking, control/monitoring systems and much more. Currently, I'm developing a monitoring system using a device from Tibbo Techonology, their DS1102.
http://tibbo.com/products/controllers/ds110x/ds1102
It's a programmable device that covers serial and ethernet communications. For my project, its main tasks are serial data collection and database population. Serial communication is done through RS485 and database used is MySQL 5.5. My database is hosted on a public IP which also runs a webserver for the interface while my device is behind a NAT. It connects to the database directly using the public IP.
I'd like to ask for advices so that I can enhance and upgrade it. Right now these are the
questions I'd like to ask.
Which is better? Having the server on a public IP or using port forwarding?
I'm also using it as webserver for the interface of my monitoring system.
To communicate with the device (rebooting, changing IP etc), I wrote an application in
python using UDP (using port 65535 of device) and also set the device to communicate with the application for specific commands. My concern is I want to encrypt the communication between my python app and the device both ways. The only available function for both encrypting and decrypting on the DS1102 is RC4. What are your thoughts on using RC4 for this application? Also, I'm planning to do port forwarding on port 65535 so that I can use my python app from the outside. Can RC4 be reliable for this too? I really want to learn how to use encryptions properly.
I'm also planning to implement SMTP for alert messages. Tibbo has a sample code from which I based mine. Problem is, it's on AUTH PLAIN LOGIN. I think I want to turn it to STARTTLS later. Can you recommend some lessons on the algorithm of STARTTLS?
What are those details on MAIL FROM:<> and RCPT TO:<>? Because on using the command
DATA, the programmer can write anyway From: and To: which can make his identity someone else.
That's it for now. Suggestions are very welcome.
You can also share some good reading materials and links. I'm always hungry for learning. :)
Thanks for your time.
2.
Encryption substitutes the confidentiality of an arbitrary amount of data (the plaintext) with the confidentiality of a small amount data (the key). In other words, your communication is only as confidential as the key – if the shared secret key leaks out, the encryption is worthless. More on this.
Also note that plain RC4 provides no authenticity (message integrity). An adversary can modify messages as much as he wants. He can even send his own messages which will be considered perfectly valid by the cipher. Verifying the validity of the messages is is up to the code that parses the messages.
If your messages are simple (only a few bytes or so), an adversary could simply send random bytes until they decrypt such that they form a valid message, without knowing anything about the key. This happens on average after only 100 attempts for a 1-byte message for example.
You will obviously have to use some sort of a nonce to prevent trivial replay attacks.
RC4 is also rather quirky per se. I guess you are already aware of the numerous "drop-n" variants and so on.
In short, protocol design is perilous. Even experts often get it wrong (look at WEP for example). The most straightforward way to solve this would be to find hardware that can handle an existing protocol such as TLS.