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Authenticating Identity
sigil
AI Agent Infrastructure · Solana

Cryptographicidentity for theagent economy.

AI agents can now transact autonomously. But without identity, authorization, and accountability — anyone claiming to be “your agent” could be anyone. Sigil fixes that.

$bun add @sigil-xyz/sdk
01Identity

Bind an agent keypair to its principal. Prove ownership on-chain.

02Authorization

Scope capabilities, enforce spend limits, set expiry — in one credential.

03Reputation

Every interaction recorded. Trust earned, not assumed.

Cryptographic Identity·Agent-to-Agent Verification·Automated Discovery·On-chain Reputation·Dynamic Authorization·Accountability Protocol·Economic Stake·Trustless Infrastructure·Cryptographic Identity·Agent-to-Agent Verification·Automated Discovery·On-chain Reputation·Dynamic Authorization·Accountability Protocol·Economic Stake·Trustless Infrastructure·
The Protocol

Critical gaps
in the agent economy.

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01/No provable identity

Identity crisis.

An agent claiming to be customer service for Company X could be anyone. There is no way to cryptographically prove an agent's principal — or verify what it is actually authorized to do.

02/No agent directory

Discovery problem.

Agents can't find each other. There is no marketplace, no directory. Only $28K in daily x402 volume — not demand-limited, discovery-limited. The pipes exist but no one can find the faucet.

03/No accountability

Reputation vacuum.

No way to know if an agent is reliable. No consequences for bad behavior. No incentive for good behavior. Trust bootstrapping requires out-of-band coordination that doesn't scale.

04/No liability model

Liability uncertainty.

When an agent misbehaves — who pays? No collateral model. No dispute resolution. The principal is fully exposed with zero on-chain recourse. This breaks at enterprise scale.

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How it works

Three stepsto trusted agents.

01

Issue.

Give your agent a credential.

A Sigil is an on-chain PDA signed to the agent's keypair and principal. Set capability scopes, daily spend limits, and collateral. One SDK call — deterministic, unforgeable.

await sigil.issue({ agent: agentPubkey, capabilities: ["payments", "read"], spendLimit: { daily: 100_000_000 }, stake: 1_000_000_000, })
02

Verify.

Every interaction, on-chain.

Any service verifies the Sigil in real time. Capability gates, spend checks, and principal attestation all happen on-chain — no centralized trust assumptions, no middleware required.

const { authorized } = await sigil.verify({ agent: incomingAgent, requiredCapability: "payments", maxSpend: amount, })
03

Transact.

With full accountability.

Your agent participates in the agent economy with verifiable identity and bounded risk. Agents discover each other via the permissionless registry. Every transaction is staked and auditable forever.

app.use(sigilMiddleware({ requireCapability: "payments", onViolation: "slash-stake", }))
Capabilities

Everythingtrust requires.

A complete identity stack for the agent economy. Issue, verify, enforce, and build — all composable, all on-chain.

On-chain identity

Every Sigil is a PDA on Solana — cryptographically tied to the agent's keypair and principal. Unforgeable, auditable, permanent.

Capability scopes

Define exactly what an agent can do: image generation, code review, payments, data access. Enforced at the protocol level.

Spend limits

Per-transaction and daily spend ceilings in USDC. Limits are verified on-chain before every transaction — no middleware needed.

Reputation scoring

Every completed transaction updates the agent's on-chain reputation score. Inspectable by anyone at any time.

Agent discovery

A permissionless registry to discover Sigil-verified agents by capability, reputation, and stake — the DNS for the agent economy.

Stake & liability

Agents post SOL collateral on Sigil issuance. Misbehavior triggers slashing. Principals have real, on-chain recourse.

Integrations

Built on the protocols
that matter.

Sigil is composable by design. Drop it into your existing stack with a single middleware call.

Solana
Settlement layer
x402
x402
Payment protocol
MCP
MCP
Model context
Helius
Solana RPC
Privy
Wallet auth
Anchor
Smart contracts
SDK · TypeScript
@sigil-xyz/sdk
import { Sigil } from "@sigil-xyz/sdk"; const sigil = new Sigil({ rpc: helius.rpcUrl, wallet: provider }); // Issue a credential const credential = await sigil.issue({ agent, capabilities, spendLimit }); // Verify in your server const { authorized } = await sigil.verify({ agent, capability: "payments" }); // Discover agents by capability const agents = await sigil.registry.find({ capability: "image-generation", minReputation: 4.0 });
Get started

Ready to trust
your agents?

Issue your first Sigil in minutes. One SDK call. No infrastructure to run. Works with any Solana wallet.

Free to startNo custodial keysOpen source SDK