Verify a signed record

Fetch a record and verify its attestation signature.

Trigger: xrpc.query:<nsid>. Needs: happyview-db, happyview-atproto.

Lua

local db = require("happyview.db")
local atproto = require("happyview.atproto")

function handle(input, ctx)
  local row = db.get(input.uri)
  if not row then
    return { error = "RecordNotFound", message = "no record at that uri" }
  end
  local record = row.record

  local verified = false
  if record.signature then
    local ok, result = pcall(
      atproto.verify_signature,
      { text = record.text, createdAt = record.createdAt },
      record.signature,
      row.did
    )
    if not ok then
      -- We could not check. Say so, rather than reporting a bad signature.
      return { record = record, verified = nil, verifyError = tostring(result) }
    end
    verified = result
  end

  return { record = record, verified = verified }
end

JavaScript

import db from "happyview.db";
import atproto from "happyview.atproto";

export default async function handle(input, ctx) {
  const row = await db.get(input.uri);
  if (!row) {
    return { error: "RecordNotFound", message: "no record at that uri" };
  }
  const record = row.record;

  let verified = false;
  if (record.signature) {
    try {
      verified = await atproto.verify_signature(
        { text: record.text, createdAt: record.createdAt },
        record.signature,
        row.did,
      );
    } catch (err) {
      // We could not check. Say so, rather than reporting a bad signature.
      return { record, verifyError: String(err) };
    }
  }

  return { record, verified };
}

TypeScript

import db from "happyview.db";
import atproto from "happyview.atproto";

export default async function handle(input: { uri: string }) {
  const row = await db.get(input.uri);
  if (!row) {
    return { error: "RecordNotFound", message: "no record at that uri" };
  }
  const record = row.record;

  let verified = false;
  if (record.signature) {
    try {
      verified = await atproto.verify_signature(
        { text: record.text, createdAt: record.createdAt },
        record.signature,
        row.did,
      );
    } catch (err) {
      // We could not check. Say so, rather than reporting a bad signature.
      return { record, verifyError: String(err) };
    }
  }

  return { record, verified };
}

How it works

1. Fetch the record by AT URI. The envelope’s did is the repo the signature was bound to. If there is no record, return a RecordNotFound error. Declare it under defs.main.errors in the lexicon, as in "errors": [{ "name": "RecordNotFound" }], for the response to be a 400; an undeclared one is sent as a 200.
2. If a signature is present, rebuild the same field table that was signed and verify it with verify_signature on happyview.atproto.
3. Return verified as true if the signature is valid, and false if it’s missing or doesn’t match.

verify_signature returns false only when it checked and the signature didn’t match. It raises when it couldn’t check at all: UNVERIFIABLE for unparseable signature bytes or a missing field, and NO_SIGNER when the instance has no key. The pcall (Lua) or try/catch (JavaScript and TypeScript) keeps that apart from a bad signature, because assigning it to verified would report a decode bug as a forged record. The script reports it as verifyError instead, with verified left unset.

Usage

TypeScript

const response = await fetch(
  "http://127.0.0.1:3000/xrpc/xyz.example.getPost?uri=at://did:plc:abc/xyz.example.post/3abc123",
);
const data = await response.json();

JavaScript

const response = await fetch(
  "http://127.0.0.1:3000/xrpc/xyz.example.getPost?uri=at://did:plc:abc/xyz.example.post/3abc123",
);
const data = await response.json();

Rust

let response = client
    .get("http://127.0.0.1:3000/xrpc/xyz.example.getPost")
    .query(&[("uri", "at://did:plc:abc/xyz.example.post/3abc123")])
    .send()
    .await?;

Go

req, _ := http.NewRequest("GET", "http://127.0.0.1:3000/xrpc/xyz.example.getPost?uri=at://did:plc:abc/xyz.example.post/3abc123", nil)
resp, err := http.DefaultClient.Do(req)

cURL

curl "http://127.0.0.1:3000/xrpc/xyz.example.getPost?uri=at://did:plc:abc/xyz.example.post/3abc123"

{
  "record": {
    "text": "Hello world",
    "createdAt": "2026-04-30T12:00:00Z",
    "signature": {
      "$type": "games.gamesgamesgamesgames.attestation",
      "key": "did:web:happyview.example.com#attestation",
      "signature": { "$bytes": "..." }
    }
  },
  "verified": true
}

Use case

Pair this with the Signed record procedure to create a write-then-verify flow. verify_signature recomputes the CID from the same fields that were signed, so a change to either field between write and read fails the check.

See Attestation signing for setup and configuration.