annulus

annulus defines the strict post-quantum profile that constrains which cryptographic operations a Quasar node accepts.

The package contains no cryptographic primitives. It expresses a policy.

Model

A Profile is a small immutable value whose flags enumerate which classical operations are forbidden. Refuse(ctx, op) reports whether a given operation is admissible under the profile bound to ctx. Profiles serialise to eight canonical bytes; Profile.Hash is the SHA3-256 of that encoding. Consensus emits the hash into block headers so any observer can determine which profile produced a block.

Policy and enforcement are decomplected. Each constrained operation (an ECDSA precompile, a pairing precompile, a Groth16 verifier) calls Refuse once at the top of its entry point and otherwise proceeds in its own lane. The profile does not know how the operations compute; the operations do not know how the profile is selected.

Profiles

Profile	Construction	Effect
Strict	annulus.Strict()	Forbids every classical category.
Permissive	annulus.Permissive()	Admits every operation.

A profile that sets StrictPQ but omits any individual Forbid* flag is ill-formed. Profile.Canonical rewrites such a profile into the canonical Strict form; Profile.Valid reports whether a profile is already in canonical form.

Categories

The Category type groups operations the same Forbid* flag governs:

Category	Members
CatECDSAContractAuth	ECDSARecover, ECDSAVerify, Schnorr
CatClassicalSig	Ed25519, X25519
CatPairingPrecompile	BN254Pairing, BLS12381Pair, BLSSignature
CatKZGPrecompile	KZGEval
CatClassicalSNARK	Groth16, Plonk, Marlin
CatNonSHA3Hash	SHA256, RIPEMD160, Blake2b, Blake2s, Keccak256

Use

import "github.com/luxfi/annulus"

// Bind the active profile once at startup.
ctx := annulus.WithProfile(context.Background(), annulus.ProfileFromEnv())

// Each constrained primitive calls Refuse at the top of its Run.
func (p *kzgPointEval) Run(ctx context.Context, in []byte) ([]byte, error) {
    if err := annulus.Refuse(ctx, annulus.KZGEval); err != nil {
        return nil, err
    }
    // ... evaluation
}

Environment

QUASAR_STRICT_PQ=1 selects Strict at startup via ProfileFromEnv. Mainnet binaries set this in their entrypoint. Any other value (including absent) selects Permissive.

Versioning

The canonical encoding is versioned. The current version is 1. Adding new fields uses the reserved tail; changing the meaning of an existing bit requires a version bump and a consensus-level upgrade.

Tests

go test ./... -count=1

The strict and permissive profile hashes are pinned in profile_test.go. A change to either is a consensus-breaking change.