Skip to main content

​
Overview

ACN uses a wallet-first, auth-optional model. Any agent can discover and use capabilities immediately — authentication is never required for core functionality. Payment is the authentication. When an agent pays on-chain, the transaction itself proves intent and identity. ACN extracts the wallet address from the payment to build reputation automatically.

​
Identity Tiers

ACN recognizes three identity tiers, each with progressively more features:
TierHow to AccessRate LimitFeatures
AnonymousNo headers20 req/min (by IP)Discover, execute, pay
Wallet-IdentifiedX-Acn-Wallet headerTrust-based (30–500/min)Above + reputation accrual
AuthenticatedAPI key or wallet signatureEntity-based (100–500/min)All above + balance, history, spend limits

​
Anonymous

Any agent can connect to ACN with no credentials and immediately:
  • Search for capabilities via acn_discover
  • Execute capabilities via acn_execute
  • Pay for capabilities and receive results via acn_submit_payment
Rate limits are applied per IP address (20 req/min).

​
Wallet-Identified

Agents that provide their wallet address in the X-Acn-Wallet header get:
  • Better rate limits based on their wallet’s trust tier
  • Reputation accrual — successful payments build trust, unlocking higher limits over time
  • Identity without friction — no signature, no challenge, no extra round-trips
X-Acn-Wallet: 0xYourWalletAddress
The wallet address is not cryptographically verified at this tier — anyone can claim any address. But reputation accrues to the paying wallet (extracted from on-chain transactions), not the claimed one. This makes spoofing pointless.

​
Authenticated

For full account features, agents authenticate with an API key or wallet signature:
  • acn_balance — check wallet balance
  • acn_call_history — view past calls and spending
  • Spend limits — per-call and daily spending caps
  • Higher base rate limits

​
API Key Authentication

​
Key Format

ACN API keys follow the format: 
acn_sk_<32 random characters>
The acn_sk_ prefix makes keys easy to identify in logs and secret scanners.

​
Usage

Pass your key in one of these ways: 
# Via dedicated header
curl https://mcp.acn.exchange/mcp \
  -H "x-acn-api-key: acn_sk_abc123def456..."

# Via Authorization header
curl https://mcp.acn.exchange/mcp \
  -H "Authorization: Bearer acn_sk_abc123def456..."

​
Security

  • Keys are hashed (SHA-256) at rest — ACN never stores your raw key
  • The prefix is stored in plaintext for identification
  • You can create multiple keys with different names for different environments
  • Rotate keys regularly from the dashboard
Your API key is shown only once when created. Store it securely — ACN cannot retrieve it for you.

​
Wallet Signature Authentication

For agents with on-chain identity, ACN supports authentication via wallet signatures.

​
How It Works

  1. Agent requests a challenge from ACN (nonce + message)
  2. Agent signs the challenge with their private key
  3. Agent initializes the MCP session with signature headers
  4. ACN verifies the signature and creates a session

​
Headers

X-Acn-Wallet: 0xYourAddress
X-Acn-Signature: 0xSignedMessage...
X-Acn-Nonce: nonce_from_challenge

​
Auto-Registration

If a wallet address authenticates for the first time, ACN automatically creates an agent account. No separate signup needed — your wallet is your identity.

​
Which Method Should I Use?

No Auth

  • You’re trying ACN for the first time
  • You want zero-friction onboarding
  • Your agent has a wallet for payments
  • You don’t need balance or history

Wallet Header

  • You want better rate limits
  • You want reputation to build over time
  • You don’t need balance or history yet
  • Simplest upgrade from anonymous

Full Auth

  • You need balance checks and call history
  • You want spend limit enforcement
  • You’re building a production agent
  • You need the highest rate limits

​
Trust Tiers

Wallet-identified and authenticated agents build trust through successful payments:
Trust TierThresholdRate Limit
NewFirst connection30 req/min
Established100 successful payments100 req/min
Trusted1,000 successful payments500 req/min
Trust is tied to the wallet address, not the session. An agent’s trust carries across sessions and even across auth methods. Use the acn_auth_status tool to check your current tier and rate limits at any time.

​
Rate Limiting

TierRate LimitScope
Anonymous20 req/minPer IP address
Wallet-Identified (new)30 req/minPer wallet
Wallet-Identified (established)100 req/minPer wallet
Wallet-Identified (trusted)500 req/minPer wallet
Authenticated (developer)100 req/minPer developer account
See Rate Limits for complete details.