---
title: Signatures: Lorg Check docs
description: Every Lorg Check answer is signed with Ed25519. What is signed, where the public keys are, and how to check a signature in a few lines of code.
url: https://lorglabs.com/docs-signatures.html
---

# Signatures

Every answer is signed, so you, or whoever you answer to, can prove later exactly what we said, about which address, at which block. Checking it is optional.

## What is signed

- **Algorithm**: Ed25519. The signature is base64url, in `signature.sig`.
- **Input**: The answer as JSON, with its `signature` field removed, in canonical form (RFC 8785, JSON Canonicalization Scheme: keys sorted, no spaces).
- **Which key**: `signature.key_id` names the key. The public keys are at `GET /v1/keys`, as a JWKS (`kty` `OKP`, `crv` `Ed25519`). Fetch them once and keep them.
- **What it covers**: Everything in the answer: the verdict, the reasons, the `block` and `as_of` it was true at, and its `request_id`, so an answer can't be passed off as another request's.

## Checking one

In JavaScript, with the browser's or Node's own crypto and the `canonicalize` package (RFC 8785):

```
import canonicalize from "canonicalize";

const { keys } = await (await fetch("https://api.lorglabs.com/v1/keys")).json();

async function isOurs(answer) {
  const { signature, ...signed } = answer;
  const jwk = keys.find((k) => k.kid === signature.key_id);
  if (!jwk) return false;
  const key = await crypto.subtle.importKey("jwk", { kty: "OKP", crv: "Ed25519", x: jwk.x }, { name: "Ed25519" }, false, ["verify"]);
  const sig = Uint8Array.from(atob(signature.sig.replace(/-/g, "+").replace(/_/g, "/")), (c) => c.charCodeAt(0));
  return crypto.subtle.verify({ name: "Ed25519" }, key, sig, new TextEncoder().encode(canonicalize(signed)));
}
```

Each service signs with its own key: `api.lorglabs.com`'s answers verify against its `/v1/keys`, the sandbox's against its own.

## When it matters

For a platform, a signed answer is a record: if a user asks why a trade was refused, or allowed, the answer you got is the proof, with the block it was true at. For an agent acting for someone, it shows the owner what the agent was told before it moved their money.