Extra 6: Stellar

  • We take for granted currency that's stable
    • good investments

  • want equitable access to financial systems
  • open membership
  • issuer-enforced finality
    • security
  • cross-issuer atomicity
    • good market to trade

  • ACH
    • requires national regulations

  • can't trade across systems paypal -> venmo?

Stellar

  • Replicated State Machine
    • keep ledger safe
    • public key authorize operations
    • accounts can issue assets
  • Transaction guarantee atomicity

  • only works if everyone agrees on ledge double-spend attack

  • think of the internet
    • transitive connections
    • China -> Stanford
    • China -/-> Google
    • Google -> Stanford

  • Stellar Consensus Protocol SCP
  • Byztentime Hypothesis
    • quorum slice - majority

  • quorum slice

  • is a quorum slice but not quorum

  • quorum tier
    • like the internet

  • citi bank sends an attack

  • ACLU doesn't agree because it has no quorum from other non-profits

  • both nodes depend on V7

  • liveness?
    • sufficiency problem
      • must be of an intact set (non-evil)

  • cascade theorem
  • federated voting
    • can get stuck
  • balloting
  • nomination

  • quorum intersecting
  • cascade until it includes all the nodes

  • crappy consensus

  • intertwined nodes cannot confirm contradictory statement
    • optimal safety

  • differ vote

  • green is in a quorum

  • will eventually cascade

  • balloting
    • federated voting can get stuck
    • invariant: all stuck and decided ballots must chose same value

  • prepare(n, x)
  • commit(n, x)
  • synchronize with timer
    • cascades

  • 1,000 operations/ledger
  • 133 nodes, 74 validators, 17 "tier-one" by 5 organizations
  • hash signing