Link to this headingSigFox

• Battery conscious of up to 10 years on a AA battery
• Limits devices to 140, 12 byte data grams per day
• Ultra narrow Band
  • Makes the signal to noise ratio better

Link to this headingUplink

• Uses Phase Modulation in the form of D-BPSK
• Uses shift registers to encode the data using (5,7) Constitutional code
  • This sends the same packet three times with no encoding, constitutional 5 and constitutional 7 encoding.
  • This is used provide error correction

Link to this headingDecoding Uplink packets

• Has a Message Authentication Code (MAC)
  • Digital Signature with symmetric key
  • May be on the flash chip in plaintext
  • Uses CBC-MAC with the Input being
    • Flags
    • Sequence ID
    • Unique Device ID
    • Payload

Example Hex Packets:

Structure of Uplink:

Link to this headingPitflaws

• MAC is at most 16 bits long

  • brute forcing can be done in 4 hours on a single frequency
  • Can be done in less time with multi frequency can be done in a mater of mins

• Sequence Number is only 12 bits so at max you can repeat a packet less than 30 days

Link to this headingDownlink

• Can only be done after a uplink that contains a downlink request
• Uses Frequency Modulation using GFSK
• Uses Scrambling with the only inputs being
  • Sequence Number
  • Device ID
• BCH (15, 11, 1) Error Correction
• Has MAC

Structure of Downlink: