VSEL

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Tech Spec

**Verifiable Semantic Execution Layer (VSEL)**

Verifiable Semantic Execution Layer (VSEL)

1. Purpose

This document defines the technical specification for implementing VSEL.

It translates:

  • formal semantics
  • invariants
  • mapping rules
  • trace requirements
  • constraint derivation
  • proof and verification logic

into enforceable engineering requirements.

The objective is:

Eliminate interpretation. Every component must behave exactly as specified or fail.

2. System Architecture Overview

VSEL is composed of the following modules:

  • Formal Specification Engine (FSE)
  • Semantic Intermediate Representation (SIR)
  • Execution Engine (EE)
  • Trace Engine (TE)
  • Constraint Engine (CE)
  • Prover (PR)
  • Verifier (VR)
  • Composition Layer (CL)

Each module must be:

  • deterministic
  • isolated
  • auditable

3. Core Data Structures

3.1 State Object

State {
  canonical: CanonicalState,
  derived: DerivedState,
  environment: Environment,
  metadata: Metadata
}

Constraints:

  • canonical must be minimal and sufficient
  • derived must be recomputable
  • environment must be explicit
  • metadata must not leak semantics

3.2 Canonical State

CanonicalState {
  accounts: Map<AccountID, AccountData>,
  storage: Map<Key, Value>,
  system_data: SystemData
}

Rules:

  • no redundant representation
  • no hidden fields
  • deterministic encoding required

3.3 Derived State

DerivedState {
  state_root: Hash,
  auxiliary_roots: Map<String, Hash>,
  aggregates: Map<String, Value>
}

Constraint:

DerivedState == Derive(CanonicalState)

3.4 Input Object

Input {
  payload: Payload,
  auth: Authorization,
  aux: AuxiliaryData
}

Rules:

  • payload defines semantics
  • auth defines permission
  • aux must not influence semantics

3.5 Trace Entry

TraceEntry {
  index: UInt64,
  pre_state_root: Hash,
  post_state_root: Hash,
  input: Input,
  observable: Observable,
  metadata: EntryMetadata
}

4. Execution Engine (EE)

4.1 Interface

Execute(state: State, input: Input) -> State

4.2 Execution Pipeline

Strict order:

  1. canonicalize input
  2. validate authorization
  3. validate preconditions
  4. apply transition
  5. validate postconditions
  6. recompute derived state
  7. update metadata

Deviation = failure.

4.3 Determinism Requirement

Execute(s, i) == Execute(s, i)

Always.

No exceptions.

4.4 Forbidden Behavior

  • implicit state mutation
  • hidden randomness
  • partial updates
  • silent failure

5. Trace Engine (TE)

5.1 Interface

RecordTransition(pre: State, input: Input, post: State) -> TraceEntry

5.2 Requirements

  • every transition recorded
  • ordering strictly enforced
  • hash chaining required

5.3 Trace Commitment

trace_root = Hash(entry_0 || entry_1 || ... || entry_n)

5.4 Replay Guarantee

Replay(trace) == original_trace

6. Semantic Mapping Enforcement

6.1 Mapping Interface

MapState(concrete_state) -> formal_state
MapInput(concrete_input) -> formal_input

6.2 Mapping Constraints

  • must be total
  • must be deterministic
  • must be canonical

6.3 Enforcement Condition

MapState(Execute(s, i)) == ApplyFormal(MapState(s), MapInput(i))

Failure = semantic violation.

7. Constraint Engine (CE)

7.1 Interface

GenerateConstraints(trace: Trace) -> ConstraintSystem

7.2 Requirements

  • constraints derived from SIR
  • no manual constraint injection
  • full coverage of transitions

7.3 Constraint Completeness

ValidTrace(trace) <=> SatisfiesConstraints(trace)

7.4 Forbidden

  • unconstrained variables
  • unused witness inputs
  • partial constraint encoding

8. Prover (PR)

8.1 Interface

Prove(trace: Trace, constraints: ConstraintSystem) -> Proof

8.2 Requirements

  • proof binds to full trace
  • witness uniquely determined
  • domain separation enforced

8.3 Output

Proof {
  commitments,
  proof_data,
  public_inputs,
  metadata
}

9. Verifier (VR)

9.1 Interface

Verify(proof: Proof) -> bool

9.2 Requirements

Verification must enforce:

  • domain correctness
  • proof validity
  • state commitment integrity
  • semantic binding

9.3 Acceptance Condition

Verify(proof) == true => ValidTrace(trace)

10. Invariant Enforcement

10.1 Implementation

Each invariant must be:

  • encoded in execution checks
  • encoded in constraints
  • enforced in verification

10.2 Failure

Any invariant violation must:

  • halt execution OR
  • produce explicit error state

11. Composition Layer (CL)

11.1 Interface

Compose(systemA, systemB) -> composed_system

11.2 Requirements

  • shared state consistency
  • cross-invariant enforcement
  • synchronized transitions

11.3 Failure Modes

  • state divergence
  • invariant violation
  • ordering mismatch

12. Cryptographic Requirements

  • all hashes must be domain-separated
  • commitments must be collision-resistant
  • signatures must be verifiable under PQC model

13. Versioning

Each component must include:

version_id
constraint_version
proof_version

Mismatch = rejection.

14. Logging vs Trace

Logs are optional. Trace is mandatory.

If something is not in the trace, it does not exist.

15. Testing Requirements

Mandatory:

  • differential tests (impl vs spec)
  • invariant fuzzing
  • constraint fuzzing
  • trace mutation testing
  • replay validation

16. Failure Handling

All failures must be:

  • explicit
  • deterministic
  • traceable

No silent degradation.

17. Performance Constraints

Optimizations must not:

  • remove constraints
  • weaken invariants
  • introduce nondeterminism

If performance conflicts with correctness, performance loses.

18. Minimal System Guarantee

The system is correct if:

Verify(Prove(trace)) == true => ValidTrace(trace)

If this is not strictly true, the system is invalid.

19. Non-Negotiable Constraints

  • no implicit behavior
  • no hidden state
  • no partial validation
  • no ambiguous encoding
  • no trust in derived values

20. Closing Statement

This specification is intentionally unforgiving.

It is designed so that:

incorrect implementations fail early instead of succeeding incorrectly.

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