Protocol Freeze — Phase 6 Audit: Auth

Date: 2026-03-29 Scope: Complete inventory of API authentication, replay protection, rate limiting, self-registration, and key management. Prerequisites: Phases 1-5 (event format, consensus, settlement, genesis, networking) are frozen. This is the final phase of the protocol freeze.

Task 1: AETHERNET-TX-V1 Signing Spec

Required HTTP Headers

# Header Format Example
1 X-AetherNet-Version String constant "AETHERNET-TX-V1"
2 X-AetherNet-Chain-ID String "aethernet-testnet-1"
3 X-AetherNet-Actor Hex-encoded Ed25519 public key (64 chars) "abc123def456..."
4 X-AetherNet-Created Unix timestamp (seconds), string "1700000000"
5 X-AetherNet-Expires Unix timestamp (seconds), string "1700000120"
6 X-AetherNet-Nonce 32 hex chars (128-bit random) "deadbeef01234567..."
7 X-AetherNet-Signature Hex-encoded Ed25519 signature (128 chars) "aabb..."

Source: internal/auth/txverify.go:43-49

Canonical Sign Bytes Construction

  1. Build a Transaction struct from the 7 headers plus r.Method and r.URL.Path
  2. Compute body_sha256 = SHA-256(JCS(request_body)) — JCS canonicalization per RFC 8785 (Phase 1). If body is not valid JSON, hash the raw bytes.
  3. json.Marshal(Transaction) → JCS canonicalize → these are the sign bytes
  4. TxID = hex(SHA-256(sign_bytes))

Source: txverify.go:110-130 (reconstruction), transaction.go:44-50 (SignBytes), transaction.go:54-61 (TxID)

Canonicalization

JCS (RFC 8785) for both the request body hash and the Transaction envelope. Verified — uses the same CanonicalizeJSON from internal/auth/canonical.go as Phase 1.

Signature Algorithm

Ed25519. ed25519.Verify(publicKey, signBytes, signature) at transaction.go:87.

Chain ID Format

"aethernet-testnet-1" for testnet, "aethernet-mainnet-1" for mainnet. Determined by AETHERNET_TESTNET env var (transaction.go:17-20).

Nonce Format

32 hex characters (128 bits of randomness). Validated at txverify.go:103-108. Client generates via os.urandom(16).hex() (Python) or os.Getenv(16).hex() (Go).

Expiry Window

  • Max lifetime: TxMaxLifetimeSecs = 120 seconds (expires_at - created_at) (transaction.go:24)
  • Clock skew tolerance: TxClockSkewSecs = 60 seconds (transaction.go:27)
  • Effective acceptance window: A transaction is accepted if now <= expires_at + 60s and created_at <= now + 60s

External Documentation

Not documented outside the code. The signing spec exists only in Go code comments and the Python SDK implementation. There is no standalone specification document.

Task 2: Signature Verification

Where Verification Happens

In the ServeHTTP method (api/server.go:823-851) — a centralized middleware that runs before request routing. Not per-handler.

Two auth schemes are checked in order:

  1. AETHERNET-TX-V1 (primary): If X-AetherNet-Version header is present, calls auth.VerifyTransaction
  2. AETHERNET-REQUEST-V1 (deprecated): If X-Aethernet-Agent-ID header is present, calls auth.VerifyRequest

Verification Order (TX-V1)

  1. Extract 7 headers (all required) — txverify.go:43-68
  2. Verify chain_id matches server config — txverify.go:71-73
  3. Parse and validate timestamps — txverify.go:76-100
  4. Validate nonce format (32 hex chars) — txverify.go:103-108
  5. Compute body_sha256 from JCS-canonicalized body — txverify.go:111-117
  6. Reconstruct Transaction struct — txverify.go:120-130
  7. Look up public key for actor — txverify.go:133-136
  8. Verify Ed25519 signature — txverify.go:139-141
  9. Compute TxID — txverify.go:144-147

Failure Response

  • Missing header: 400 Bad Request with "tx: missing required header: X-AetherNet-..."
  • Chain mismatch: 400 with "tx: chain_id mismatch"
  • Expired: 400 with "tx: transaction expired"
  • Bad signature: 400 with "tx: signature verification failed"
  • Rate limited: 429 Too Many Requests with Retry-After header

Source: server.go:837-851

Body Consumption

The body is read once into bodyBytes at the top of ServeHTTP (server.go:800-810), then wrapped in a bytes.NewReader and set back on r.Body for downstream handlers. This avoids the double-read issue.

Endpoints That Don’t Require Signing

All GET endpoints do not require signing. The middleware only rejects unsigned write operations when requireAuth=true (server.go:899-913).

Write Endpoints Missing Auth

CRITICAL findings from the exploration:

Endpoint Method Auth status
POST /v1/platform/keys POST NONE — anyone can generate API keys
POST /v1/registry POST NONE — no signature, no ownership check
DELETE /v1/registry/{id} DELETE PARTIAL — only node’s own identity
POST /v1/router/register POST NONE — no signature, no ownership check
DELETE /v1/router/register/{id} DELETE NONE — no signature, no ownership check
PUT /v1/router/availability/{id} PUT NONE — no signature, no ownership check

These L2 (coordination layer) endpoints were added after the auth middleware was designed for L1 (core protocol) endpoints. They bypass checkTxIDSeen and getAuthAgent.

grep Verification Output 

398:  mux.HandleFunc("POST /v1/agents", s.handleRegisterAgent)
404:  mux.HandleFunc("POST /v1/transfer", s.handleTransfer)
405:  mux.HandleFunc("POST /v1/generation", s.handleGeneration)
406:  mux.HandleFunc("POST /v1/verify", s.handleVerify)
415:  mux.HandleFunc("POST /v1/stake", s.handleStake)
416:  mux.HandleFunc("POST /v1/unstake", s.handleUnstake)
417:  mux.HandleFunc("POST /v1/faucet", s.handleFaucet)
435:  mux.HandleFunc("POST /v1/registry", s.handlePostRegistry)
438:  mux.HandleFunc("DELETE /v1/registry/{agent_id}", s.handleDeleteRegistry)
443:  mux.HandleFunc("POST /v1/router/register", s.handleRouterRegister)
444:  mux.HandleFunc("DELETE /v1/router/register/{agent_id}", s.handleRouterUnregister)
445:  mux.HandleFunc("PUT /v1/router/availability/{agent_id}", s.handleRouterAvailability)
457:  mux.HandleFunc("POST /v1/tasks", s.handlePostTask)
468:  mux.HandleFunc("POST /v1/tasks/{id}/trajectory/commit", s.handleTrajectoryCommit)
469:  mux.HandleFunc("POST /v1/tasks/{id}/claim", s.handleClaimTask)
470:  mux.HandleFunc("POST /v1/tasks/{id}/submit", s.handleSubmitTask)
471:  mux.HandleFunc("POST /v1/tasks/{id}/approve", s.handleApproveTask)
472:  mux.HandleFunc("POST /v1/tasks/{id}/dispute", s.handleDisputeTask)
473:  mux.HandleFunc("POST /v1/tasks/{id}/cancel", s.handleCancelTask)
474:  mux.HandleFunc("POST /v1/tasks/{id}/subtask", s.handleCreateSubtask)
476:  mux.HandleFunc("POST /v1/replay/outcome", s.handleReplayOutcome)
479:  mux.HandleFunc("POST /v1/replay/submit", s.handleReplaySubmit)
482:  mux.HandleFunc("POST /v1/challenges/{id}/resolve", s.handleResolveChallenge)
483:  mux.HandleFunc("POST /v1/challenges", s.handleOpenChallenge)
490:  mux.HandleFunc("POST /v1/platform/keys", s.handleGenerateKey)
492:  mux.HandleFunc("DELETE /v1/platform/keys/{key}", s.handleRevokeKey)

Task 3: TxID Replay Protection

How TxID Is Computed

TxID = hex(SHA-256(JCS(json.Marshal(Transaction)))) — deterministic from the transaction’s canonical bytes. Same transaction → same TxID on every node.

Source: transaction.go:54-61

Storage

Dual-layer:

  1. In-memory hot cache: TxIDStore.local map[string]int64 — keyed by "txid:" + txID, value is Unix timestamp
  2. BadgerDB persistence: PutMeta("txid:" + txID, timestamp) — survives restarts

Source: txidstore.go:14-57

TTL

10 minutes (txidTTL = 10 * time.Minute, txidstore.go:9). Cleanup goroutine runs every 5 minutes, evicting entries older than 10 minutes from the in-memory cache. BadgerDB entries are NOT explicitly cleaned (they’re harmless — the timestamp check prevents reuse).

Duplicate Request Handling

checkTxIDSeen (server.go:610-648):

  1. Extract TxID from verified transaction context
  2. Call txIDStore.MarkSeen(txID) — returns true if already seen
  3. If already seen: return 409 Conflict with "DUPLICATE_TX" code and the TxID
  4. The response is idempotent — the first request succeeds, subsequent ones get 409

Collision Probability

TxID is SHA-256(sign_bytes) which includes a 128-bit random nonce. Collision probability is negligible (birthday bound at ~2^128 for the nonce alone, further mixed with timestamp, actor, path, and body hash).

After Node Restart

Yes, previously seen TxIDs are still rejected. BadgerDB persistence survives restarts. MarkSeen checks BadgerDB when the in-memory cache misses (txidstore.go:44-48).

Cross-Node Replay

Not protected. Each node maintains its own TxIDStore. The same signed request hitting two different nodes via ALB will succeed on both. This is a known limitation — the consensus layer (Phase 2) is the authoritative deduplication mechanism for economic operations (same event can’t be finalized twice).

Task 4: Rate Limiting

Rate Limit Types

Three-dimensional per-endpoint limiting (auth/ratelimiter.go):

  1. Per-agent per-hour — limits how many requests a single signing identity can make
  2. Per-IP per-hour — limits requests from a single IP address
  3. Global per-hour — limits total requests to an endpoint across all callers

Configured Limits

Endpoint Per-Agent/hr Per-IP/hr Global/hr
/v1/agents unlimited 3 30
/v1/faucet 1 3 84
/v1/tasks 20 50 500
/v1/tasks/claim 60 200 2000
/v1/tasks/submit 60 200 2000
/v1/tasks/approve 60 200 2000
/v1/tasks/dispute 10 50 200
/v1/tasks/cancel 20 50 500
/v1/transfer 120 300 3000
/v1/stake 20 100 500
/v1/unstake 20 100 500
/v1/challenge 10 50 200

Source: auth/ratelimiter.go:18-31

Additionally, AgentRateLimiter (auth/ratelimit.go) provides a separate per-agent hourly cap applied in the ServeHTTP middleware (server.go:842).

Storage

In-memory only. Rate limit counters are not persisted to BadgerDB and reset on node restart. Each node tracks independently.

Exceeded Behavior

429 Too Many Requests with Retry-After header indicating seconds until the current hour window resets.

Bypass Vectors

  • Key rotation: Generating a new Ed25519 key creates a new agent identity, resetting per-agent limits. Combined with open self-registration, an attacker can create unlimited identities.
  • IP rotation: Different source IPs bypass per-IP limits.
  • Multi-node: Per-node rate limits mean an attacker can hit each node at the full limit (3 nodes × limit).
  • Missing endpoints: L2 endpoints (/v1/registry, /v1/router/*, /v1/platform/keys) have no rate limits configured.

Cross-Node Consistency

Not consistent. Rate limits are per-node in-memory. An attacker can hit each node independently.

Task 5: Self-Registration Auth

Resolving the Chicken-and-Egg Problem

When VerifyTransaction looks up the actor’s public key and the actor is not registered, it falls back to hex-decoding the actor field itself as the public key (server.go:830-834):

pubBytes, hexErr := hex.DecodeString(actor)
if hexErr == nil && len(pubBytes) == 32 {
    return ed25519.PublicKey(pubBytes), nil
}

The actor IS the hex-encoded public key. The server uses it directly for signature verification without needing a prior registry entry. After signature verification succeeds, handleRegisterAgent uses the verified actor as the new agent’s identity.

Can an Attacker Register with Someone Else’s Key?

No. The actor field must be the hex encoding of the signer’s public key. The signature is verified against this key (txverify.go:139). An attacker would need the victim’s private key to produce a valid signature for the victim’s public key.

Can an Attacker Replay a Registration Request?

Yes, but harmlessly. Registration is idempotent — handleRegisterAgent does not call checkTxIDSeen. Re-registering an already-registered agent returns the existing identity (status 409, “already registered”). The onboarding grant is also idempotent (checked by balance/agent count).

Registration Spam Prevention

  • IP rate limit: 3 registrations per IP per hour, 30 global per hour (ratelimiter.go:19)
  • No per-agent limit on /v1/agents (PerAgentPerHr: 0) — because the agent doesn’t exist yet
  • No proof of work or invite required
  • Onboarding cost: Each registration triggers an onboarding grant from the ecosystem bucket, which is finite. After 800,000 registrations, the onboarding allocation is exhausted.

Task 6: Key Management

Private Key Storage

Client-side only. Private keys are never sent to the server. The server only sees the hex-encoded public key (as the actor/AgentID) and the signature.

Python SDK stores keys at ~/.aethernet/keys/{name}.json with 0o600 permissions (signing.py:136-143). File format:

{"seed": "<hex-encoded 32-byte Ed25519 seed>", "public_key": "<hex>"}

Go node stores keys at {data_dir}/node_keys/identity.json with scrypt encryption (internal/crypto/keys.go).

Key Format

Ed25519 seed (32 bytes), stored as hex. The full keypair is derived from the seed. No PKCS8 or X.509 wrapping.

Key Rotation

Not supported at the agent level. An agent’s identity IS its public key. Changing the key means creating a new identity. There is no mechanism to link old and new identities.

Supported at the validator level. The ValidatorKeyRotate event type (event.go:124) allows validators to rotate their consensus key while keeping their seat identity. This rotates the operator/consensus key, not the agent identity.

Key Compromise Recovery

No revocation mechanism. If an agent’s private key is compromised:

  • The attacker can sign requests as the agent
  • There is no way to revoke the compromised key
  • The agent must create a new identity (new key) and transfer assets manually
  • Staked funds under the compromised key cannot be unstaked without the private key

For validators: key rotation via ValidatorKeyRotate allows switching to a new key, but requires the old key to sign the rotation event. If the old key is compromised, the attacker could rotate first.

Task 7: Gap Analysis

GAPS THAT BLOCK PROTOCOL FREEZE

1. L2 endpoints lack auth — router/register, registry, platform/keys are completely open

POST /v1/router/register, DELETE /v1/router/register/{id}, PUT /v1/router/availability/{id}, POST /v1/registry, and POST /v1/platform/keys have NO signature verification and NO checkTxIDSeen. Any caller can:

  • Register any agent for autonomous task routing
  • Unregister any agent from routing
  • Toggle any agent’s availability
  • Create service listings for any agent
  • Generate unlimited API keys

Recommendation: Add getAuthAgent checks to all L2 write endpoints. Require that the authenticated agent matches the target agent_id.

2. TX-V1 signing spec is not documented outside the code

The complete signing specification — header format, canonical bytes construction, JCS canonicalization rules — exists only in Go code and Python SDK. Third-party implementers must reverse-engineer the spec from code.

Recommendation: Create docs/tx-v1-signing-spec.md with the complete specification, test vectors, and example implementations.

3. L2 endpoints have no rate limits

/v1/registry, /v1/router/*, and /v1/platform/keys are not in DefaultLimits() (ratelimiter.go:18-31). They have zero rate limiting.

Recommendation: Add rate limits for all L2 write endpoints.

4. No rate limiting on registration at the per-agent level

/v1/agents has PerAgentPerHr: 0 — unlimited per-agent. Combined with open self-registration (any Ed25519 key can register), an attacker can create thousands of identities per hour limited only by IP (3/hr/IP) and global (30/hr).

Recommendation: The IP and global limits are the primary defense. Consider adding proof-of-work or a deposit requirement for mainnet.

RISKS FOR MAINNET

1. Cross-node replay via ALB

The same signed request hitting multiple nodes via the load balancer succeeds on all of them. For transfers and tasks, this is harmless (the DAG deduplicates the resulting events). For faucet grants, the cooldown is per-ledger (per-node), so a grant could succeed on multiple nodes simultaneously.

2. Key compromise with no revocation

A compromised agent key allows the attacker to spend all the agent’s balance, unstake their tokens, and act in their name. There is no emergency freeze or key revocation mechanism.

3. Rate limit bypass via identity rotation

An attacker can generate new Ed25519 keys rapidly, register each one, and use the per-agent limits of each new identity. The IP limit (3/hr) and global limit (30/hr) on /v1/agents are the only defense.

4. Registration spam creating unbounded state

Each registration creates an identity registry entry, a faucet grant (from ecosystem bucket), and potentially staking entries. With 800,000 max registrations and ~100 AET minimum per agent, the total state is bounded but large.

5. --no-auth flag disables all protection

When --no-auth is set, ALL write operations are accepted unsigned. This is documented as testnet-only but there is no enforcement mechanism.

THINGS ALREADY SOLID

1. Ed25519 signing with JCS canonicalization

The TX-V1 scheme uses Ed25519 for signatures and RFC 8785 JCS for canonical bytes. Both are industry-standard, deterministic, and cross-language compatible. The same sign bytes produce identical signatures in Go and Python (verified by cross-language test vectors in Phase 1).

2. Self-registration verification is cryptographically sound

The actor-as-public-key pattern elegantly solves the chicken-and-egg problem. Only the holder of the corresponding private key can register a given public key as an agent. The signature proves possession without requiring pre-registration.

3. Nonce-based replay protection with persistence

TxIDs (SHA-256 of sign bytes) are stored in both in-memory cache and BadgerDB. Replayed requests are rejected with 409. The 10-minute TTL covers the 2-minute transaction lifetime with margin.

4. Three-dimensional rate limiting

Per-agent, per-IP, and global limits provide defense-in-depth. An attacker must bypass all three dimensions simultaneously to exceed limits.

5. Body re-read prevention

The ServeHTTP middleware reads the body once, stores it as bodyBytes, and wraps it in a bytes.NewReader for downstream handlers. This prevents the double-read bug that plagues many Go HTTP servers with body-consuming middleware.

6. Timestamp-based transaction expiry

The 120-second max lifetime with 60-second clock skew tolerance provides a tight window. Transactions cannot be stockpiled for later replay.

7. Idempotent registration

handleRegisterAgent is idempotent — re-registering an existing agent returns 409 without side effects. The onboarding grant is also idempotent (checked by agent count).

Summary of Action Items (Priority Order)

# Action Severity Effort
1 Add TX-V1 auth to L2 write endpoints (registry, router, platform/keys) Blocks freeze Medium
2 Add rate limits for L2 endpoints Blocks freeze Low
3 Create TX-V1 signing spec document Blocks freeze Medium
4 Add faucet cross-node dedup (ledger-based cooldown already exists but verify ALB behavior) Pre-mainnet Low
5 Add key revocation / emergency freeze mechanism Pre-mainnet High
6 Add proof-of-work or deposit for registration on mainnet Pre-mainnet Medium
7 Remove --no-auth flag or require explicit confirmation Pre-mainnet Low

AetherNet — The Financial System for Autonomous AI Agents

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