In this presentation, I discuss my recent project that aims to make time-series data better encrypted. Currently, encryption among several clients relies on static keys. This is far from ideal, as it means that compromised keys can result in the entire communication chain becoming compromised. Using polynomials, we can efficiently update shared keys among large networks. Applications for this include: - VoIP and Teleconferencing - DRM for TV Networks - Secure Radio Broadcasts - Group Messaging Learn more at https://www.alexbeaver.com/events/encryption-of-time-series-data

1. Encryption of
Time-Series Data
Alex Beaver
alex@beaver.dev
linkedin.com/in/alex-beaver/
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2. Alex Beaver
1st Year CSEC Major
• From SF Bay Area
• 2 Enterprise Security
Internships
• Interested in
cryptography and
secure communication
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3. Agenda
• The State of Key
Ratcheting
• A Scalable Solution
• Potential Use Cases
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4. Agenda
• The State of Key
Ratcheting
• A Scalable Solution
• Potential Use Cases
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5. How do You Secure
Communication
Between Many
Clients?
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6. Static Keys
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7. Static
Keys
• Risk of key compromise
• Difficult to kick clients
• Easy to crack
• Can fix with key
ratcheting
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8. Key
Ratcheting
• Update Keys Over Time
• Common in messaging
clients
• If one key is
compromised, future
aren’t
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9. Works Best
P2P
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10. Well-
Established
Standards
• Diffie Hellman
• ECDH
• Signal Protocol
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11. Not Scalable
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12. Agenda
• The State of Key
Ratcheting
• A Scalable Solution
• Potential Use Cases
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13. Requirements
• Multicast compatible
• Near-infinite # of
clients
• More secure than static
keys
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14. The Concept
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MSG 1 MSG 2 MSG 3 MSG 4
New Key New Key New Key New Key

15. Don’t Want to Transfer Keys
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MSG 1 MSG 2 MSG 3 MSG 4
New Key New Key New Key New Key

16. Polynomials
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17. Why
Polynomials?
• Very flexible
• Efficient calculation
• Deterministic
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18. Deriving a Key from a Polynomial
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Key
Polynomial

19. Deriving a Nonce from a Polynomial
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Nonce
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Key

20. Deriving a Next X from a Polynomial
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X
ID*
* May not be necessary depending on configuration
Nonce
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Key

21. What Do
We Have?
• Common Algorithm
Across All Clients
• Convert Highly Flexible
Data Set to AES-256
Keys
• Missing Key Ratcheting
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22. Highly
Flexible
Data Set
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23. Modify
Coefficients
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24. Modify
Coefficients
• Establish a changelog
• Wrap around sent data
• If a client does not
receive, loses access to
chain
• Lightning fast
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25. The Concept
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MSG 1 MSG 2 MSG 3 MSG 4
Changelog Changelog Changelog Changelog

26. Single Packet Compromise
• Attacker likely doesn’t have coefficient set
• Cannot go backwards
• Have “next x” n iterations in the future
• Would have to compromise n sequential packets
• Coefficients more difficult to brute-force than sym. key
• Unknown # of coefficients
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27. Caveats
• Recovery mechanism
• Client Kick
• Works best when # coefficients bounded (1024-8192)
• Expensive
• If coefficients at any stage compromised, chain
becomes compromised
• NaN/∞
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28. What Do
We Have?
• Common Algorithm
Generate Keys
• Independent
Ratcheting
• Compromised packet
does not compromise
security
• Constant complexity
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29. Agenda
• The State of Key
Ratcheting
• A Scalable Solution
• Potential Use Cases
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30. Real Time
or At Rest
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31. Potential
Use Cases
• Radio
• Secure VoIP
• IPTV DRM
• Group Messaging
• Time-Series Databases
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