Byzantine fault tolerance for peer-to-peer collaboration

Slides from a talk at KASTEL Distinguished Lecture Series, given at Karlsruhe Institute of Technology, Germany on 19 October 2023.
https://cybersec.kcist.kit.edu/473.php
https://martin.kleppmann.com/2023/10/19/kastel-distinguished-lecture.html

Abstract:

When developing web applications, the number one security rule is that the server should never trust anything it receives from clients. When developing peer-to-peer software, the equivalent rule is that a peer should never trust anything it receives from other peers. Unfortunately, many researchers working on peer-to-peer applications seem to have forgotten this rule. There have been efforts to build, for example, P2P equivalents of Google Docs, but they mostly assume trusted peers that correctly follow the protocol. A malicious peer can easily cause permanent inconsistencies in a document.

This talk will introduce our work-in-progress research on making collaboration software robust against malicious (Byzantine) peers. Hint: there are no consensus algorithms and no blockchains involved!

Transcript

1. View Slide

2. Figma
   

   View Slide

3. View Slide

4. View Slide

5. View Slide

6. View Slide

7. View Slide

8. View Slide

9. View Slide

10. View Slide

11. View Slide

12. View Slide

13. View Slide

14. View Slide

15. View Slide

16. View Slide

17. View Slide

18. View Slide

19. View Slide

20. View Slide

21. View Slide

22. 22
    https://arxiv.org/abs/2012.00472
    

    View Slide

23. View Slide

24. View Slide

25. View Slide

26. View Slide

27. View Slide

28. View Slide

29. View Slide

30. View Slide

31. View Slide

32. View Slide

33. View Slide

34. View Slide

35. View Slide

36. View Slide

37. View Slide

38. View Slide

39. View Slide

40. View Slide

41. View Slide

42. work in progress
    

    View Slide

43. View Slide

44. View Slide

45. View Slide

46. View Slide

47. View Slide

48. View Slide

49. View Slide

50. View Slide

51. View Slide

52. View Slide

53. View Slide

54. View Slide

55. View Slide

56. View Slide

57. View Slide

58. View Slide

59. View Slide

60. View Slide

61. View Slide

62. View Slide

63. View Slide

64. View Slide

65. View Slide

66. View Slide

67. View Slide

68. View Slide

69. View Slide

70. View Slide

71. View Slide

72. View Slide

73. View Slide

74. View Slide

75. View Slide

76. View Slide

77. View Slide

78. View Slide

79. View Slide

80. View Slide

81. View Slide

82. References
    • M. Kleppmann. Making CRDTs Byzantine Fault Tolerant. PaPoC 2022.
    doi:10.1145/3517209.3524042
    • M. Kleppmann, H. Howard. Byzantine Eventual Consistency and the
    Fundamental Limits of Peer-to-Peer Databases. Preprint, 2020.
    https://arxiv.org/abs/2012.00472
    • M. Weidner, M. Kleppmann, D. Hugenroth, A.R. Beresford. Key
    Agreement for Decentralized Secure Group Messaging with Strong
    Security Guarantees. ACM CCS 2021. doi:10.1145/3460120.3484542
    • D. Hugenroth, M. Kleppmann, A.R. Beresford. Rollercoaster: An Efficient
    Group-Multicast Scheme for Mix Networks. USENIX Security 2021
    • S.A. Kollmann, M. Kleppmann, A.R. Beresford. Snapdoc: Authenticated
    snapshots with history privacy in peer-to-peer collaborative editing.
    PETS 2019. doi:10.2478/popets-2019-0044
    • M. Kleppmann, A. Wiggins, P. van Hardenberg, M. McGranaghan. Local-
    first software: You own your data, in spite of the cloud. Onward! 2019.
    doi:10.1145/3359591.3359737
    • More at https://martin.kleppmann.com
    82
    

    View Slide