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Layer 2 Boundaries & Trust Models

vProgs Status: ACTIVE DEVELOPMENT / PROTOTYPE | Igra / Kasplex L2: EXTERNAL ARCHITECTURES

As Kaspa expands its capabilities post-Toccata, the term "Layer 2" (L2) is often overloaded. It is critical to distinguish between the different architectures leveraging Kaspa.

Sovereign Verifiable Programs (vProgs)​

  • Execution: Off-chain sovereign runtime.
  • VM Compatibility: Custom verifiable programs (e.g., RISC Zero guests). Not EVM.
  • Settlement: Kaspa L1 covenants using OpZkPrecompile.
  • State: Application state is off-chain; L1 only tracks state roots and sequencing commitments.

EVM-Compatible Based Rollups (Kasplex L2 / Igra)​

Kaspa L1 does not execute EVM bytecode, and Toccata is not an EVM hard fork.

External projects (like the Igra implementation or Kasplex L2 architecture) may build EVM-compatible "based rollups".

  • Execution: Off-chain EVM node.
  • VM Compatibility: EVM.
  • Sequencing: Derives ordering from Kaspa L1 (Based).
  • Bridge: May rely on trusted MPC (Multi-Party Computation) bridges initially, or validity-proof (ZK) bridges if/when fully implemented.

Note: Kasplex L1 (Asset Hub) is distinct from Kasplex L2 Architecture.

The "Trustless" Terminology Trap​

Avoid using the word "trustless" casually when describing L2s or bridges.

  1. Validity-Proof Enforced Exit: A ZK bridge uses Kaspa's OpZkPrecompile to verify that an L2 withdrawal is valid according to the L2's state rules. This removes the need to trust an MPC committee for correctness.
  2. Remaining Trust Assumptions: Even with a ZK bridge, you must still trust:
    • Data Availability: Can you get the data needed to construct the withdrawal proof?
    • Operator Liveness: Will the sequencer/prover actually process your exit?
    • Censorship Resistance: Can you force an L1 exit if the L2 sequencer ignores you?

A bridge is only as secure as its weakest assumption. Toccata's consensus primitives do not automatically make an external bridge "trustless" simply by existing.