orchestrator/src/services/eventBus.ts

@@ -22,6 +22,12 @@ import { createHash, createHmac } from "crypto";
 import { EventEmitter } from "events";
 import { query } from "../db/postgres";
 import { logger } from "../logging/logger";
+import {
+  getEventSigner,
+  legacyHmac,
+  resolveSigningMode,
+  type EventSignInput,
+} from "./eventSigner";
 
 /**
  * Normalised event types — arch §7.2. Keep this list as the single
@@ -110,7 +116,13 @@ export async function publish(input: PublishInput): Promise<EventRecord> {
     [input.planId],
   );
   const prevHash = prev.length > 0 ? prev[0].signature : null;
-  const signature = sign(input.planId, input.type, payloadHash, prevHash);
+  const signInput: EventSignInput = {
+    planId: input.planId,
+    type: input.type,
+    payloadHash,
+    prevHash,
+  };
+  const signature = await getEventSigner().sign(signInput);
 
   const rows = await query<EventRecord>(
     `INSERT INTO events (plan_id, type, actor, payload, payload_hash, prev_hash, signature)
@@ -171,9 +183,23 @@ export async function verifyChain(planId: string): Promise<
     if (expectedPayloadHash !== e.payload_hash) {
       return { ok: false, brokenAt: i, reason: "payload_hash mismatch" };
     }
-    const expectedSig = sign(e.plan_id, e.type, e.payload_hash, e.prev_hash);
-    if (expectedSig !== e.signature) {
-      return { ok: false, brokenAt: i, reason: "signature mismatch" };
+    const signInput: EventSignInput = {
+      planId: e.plan_id,
+      type: e.type,
+      payloadHash: e.payload_hash,
+      prevHash: e.prev_hash,
+    };
+    const signer = getEventSigner();
+    const ok = await signer.verify(signInput, e.signature);
+    // Back-compat: rows persisted before EVENT_SIGNING_MODE existed are
+    // HMAC, so if the active signer rejects them, fall through to the
+    // legacy check before declaring a mismatch.
+    if (!ok && legacyHmac(signInput) !== e.signature) {
+      return {
+        ok: false,
+        brokenAt: i,
+        reason: `signature mismatch (mode=${resolveSigningMode()})`,
+      };
     }
     prevSig = e.signature;
   }

orchestrator/src/services/eventSigner.ts

@@ -0,0 +1,302 @@
+/**
+ * Pluggable event signer (arch §7.5, §13; gap-analysis v2 §7.5 / §10.5).
+ *
+ * Three interchangeable strategies, selected via EVENT_SIGNING_MODE:
+ *
+ *   - `hmac`   (default; back-compat) HMAC-SHA256 keyed by
+ *              EVENT_BUS_HMAC_SECRET / SESSION_SECRET.
+ *   - `eip712` EIP-712 typed-data signature produced via ethers (when
+ *              ORCHESTRATOR_PRIVATE_KEY is set) or via the HSM
+ *              (services/hsm.ts) if EVENT_SIGNING_HSM_KEY_ID is set
+ *              and the HSM sign() path returns a 65-byte secp256k1
+ *              compact signature. Domain = {name: "CurrenciCombo",
+ *              version: "1", chainId: CHAIN_138_CHAIN_ID (138 by default)}.
+ *   - `jws`    Compact JWS with HS256 headers, keyed by
+ *              EVENT_BUS_HMAC_SECRET.
+ *
+ * All strategies produce an opaque `string` signature suitable for
+ * persisting to `events.signature` (varchar). Verification is done
+ * by the same strategy code path — the prior record's signature is
+ * still chained via `prev_hash` regardless of the mode.
+ */
+
+import { createHmac, createHash } from "crypto";
+import { ethers } from "ethers";
+import { getHSMService } from "./hsm";
+
+export type SigningMode = "hmac" | "eip712" | "jws";
+
+export interface EventSignInput {
+  planId: string;
+  type: string;
+  payloadHash: string;
+  prevHash: string | null;
+}
+
+export interface EventSigner {
+  readonly mode: SigningMode;
+  sign(input: EventSignInput): Promise<string>;
+  verify(input: EventSignInput, signature: string): Promise<boolean>;
+}
+
+/* --------------------------------------------------------------------
+ * Shared canonical payload used across modes. Keeping it stable means
+ * a signature produced in one mode can, in principle, be replayed into
+ * a verifier configured for the same mode on another replica.
+ * ----------------------------------------------------------------- */
+function canonicalMessage(input: EventSignInput): string {
+  return `${input.planId}|${input.type}|${input.payloadHash}|${input.prevHash ?? ""}`;
+}
+
+/* --------------------------------------------------------------------
+ * HMAC (default / back-compat with the pre-existing signing scheme).
+ * ----------------------------------------------------------------- */
+function getHmacSecret(): string {
+  return (
+    process.env.EVENT_BUS_HMAC_SECRET ??
+    process.env.SESSION_SECRET ??
+    "dev-event-bus-secret-change-in-production"
+  );
+}
+
+class HmacSigner implements EventSigner {
+  readonly mode: SigningMode = "hmac";
+  async sign(input: EventSignInput): Promise<string> {
+    return createHmac("sha256", getHmacSecret())
+      .update(canonicalMessage(input))
+      .digest("hex");
+  }
+  async verify(input: EventSignInput, signature: string): Promise<boolean> {
+    const expected = await this.sign(input);
+    return timingSafeEqual(expected, signature);
+  }
+}
+
+/* --------------------------------------------------------------------
+ * EIP-712 — typed-data signing via ethers. Structured according to
+ * EIP-712; domain separator pins the signer to Chain-138 orchestrator.
+ * ----------------------------------------------------------------- */
+function getEip712Domain() {
+  const chainId = Number(process.env.CHAIN_138_CHAIN_ID ?? 138);
+  return {
+    name: "CurrenciCombo",
+    version: "1",
+    chainId,
+    verifyingContract:
+      process.env.NOTARY_REGISTRY_ADDRESS ??
+      "0x0000000000000000000000000000000000000000",
+  } as const;
+}
+
+const EIP712_TYPES: Record<string, Array<{ name: string; type: string }>> = {
+  Event: [
+    { name: "planId", type: "string" },
+    { name: "eventType", type: "string" },
+    { name: "payloadHash", type: "bytes32" },
+    { name: "prevHash", type: "bytes32" },
+  ],
+};
+
+function toBytes32(hexOrHash: string | null): string {
+  if (!hexOrHash) return "0x" + "0".repeat(64);
+  const h = hexOrHash.startsWith("0x") ? hexOrHash.slice(2) : hexOrHash;
+  // hash is sha256 (64 hex chars) — just pad/trim to 32 bytes.
+  if (h.length === 64) return `0x${h}`;
+  if (h.length > 64) return `0x${h.slice(0, 64)}`;
+  return `0x${h.padEnd(64, "0")}`;
+}
+
+class Eip712Signer implements EventSigner {
+  readonly mode: SigningMode = "eip712";
+  private wallet: ethers.Wallet | null = null;
+
+  constructor() {
+    const pk = process.env.ORCHESTRATOR_PRIVATE_KEY;
+    if (pk && /^0x[0-9a-fA-F]{64}$/.test(pk)) {
+      this.wallet = new ethers.Wallet(pk);
+    }
+  }
+
+  private messageValue(input: EventSignInput) {
+    return {
+      planId: input.planId,
+      eventType: input.type,
+      payloadHash: toBytes32(input.payloadHash),
+      prevHash: toBytes32(input.prevHash),
+    };
+  }
+
+  async sign(input: EventSignInput): Promise<string> {
+    const message = this.messageValue(input);
+    if (this.wallet) {
+      // ethers v6: signTypedData(domain, types, value)
+      return this.wallet.signTypedData(getEip712Domain(), EIP712_TYPES, message);
+    }
+    // HSM fallback — the mock HSM returns an opaque buffer. Wrap it
+    // with the domain digest so it is still tamper-evident against
+    // the canonical message.
+    const digest = ethers.TypedDataEncoder.hash(
+      getEip712Domain(),
+      EIP712_TYPES,
+      message,
+    );
+    const hsm = getHSMService();
+    const keyId = process.env.EVENT_SIGNING_HSM_KEY_ID ?? "orchestrator";
+    const raw = await hsm.sign(Buffer.from(digest.slice(2), "hex"), keyId);
+    return `0x${raw.toString("hex")}`;
+  }
+
+  async verify(input: EventSignInput, signature: string): Promise<boolean> {
+    const message = this.messageValue(input);
+    if (!signature.startsWith("0x")) return false;
+    try {
+      const recovered = ethers.verifyTypedData(
+        getEip712Domain(),
+        EIP712_TYPES,
+        message,
+        signature,
+      );
+      if (this.wallet) {
+        return recovered.toLowerCase() === this.wallet.address.toLowerCase();
+      }
+      // HSM-backed: fall back to validity check only (we don't know
+      // the pubkey without a separate HSM round-trip).
+      return /^0x[0-9a-fA-F]+$/.test(signature);
+    } catch {
+      // Not an ECDSA signature (likely HSM-opaque). Return best-effort
+      // by delegating to the HSM.
+      const digest = ethers.TypedDataEncoder.hash(
+        getEip712Domain(),
+        EIP712_TYPES,
+        message,
+      );
+      const hsm = getHSMService();
+      const keyId = process.env.EVENT_SIGNING_HSM_KEY_ID ?? "orchestrator";
+      const raw = Buffer.from(signature.slice(2), "hex");
+      return hsm.verify(Buffer.from(digest.slice(2), "hex"), raw, keyId);
+    }
+  }
+}
+
+/* --------------------------------------------------------------------
+ * JWS compact (HS256). Useful when signing has to travel through a
+ * JWT-aware infrastructure layer (API gateway, service mesh).
+ * ----------------------------------------------------------------- */
+function base64UrlEncode(input: Buffer | string): string {
+  const buf = Buffer.isBuffer(input) ? input : Buffer.from(input);
+  return buf
+    .toString("base64")
+    .replace(/\+/g, "-")
+    .replace(/\//g, "_")
+    .replace(/=+$/, "");
+}
+
+class JwsSigner implements EventSigner {
+  readonly mode: SigningMode = "jws";
+  async sign(input: EventSignInput): Promise<string> {
+    const header = base64UrlEncode(
+      JSON.stringify({ alg: "HS256", typ: "JWS", kid: "event-bus" }),
+    );
+    const body = base64UrlEncode(
+      JSON.stringify({
+        planId: input.planId,
+        type: input.type,
+        payloadHash: input.payloadHash,
+        prevHash: input.prevHash,
+        iat: Math.floor(Date.now() / 1000),
+      }),
+    );
+    const signingInput = `${header}.${body}`;
+    const mac = createHmac("sha256", getHmacSecret())
+      .update(signingInput)
+      .digest();
+    return `${signingInput}.${base64UrlEncode(mac)}`;
+  }
+
+  async verify(input: EventSignInput, jws: string): Promise<boolean> {
+    const parts = jws.split(".");
+    if (parts.length !== 3) return false;
+    const [header, body, sig] = parts;
+    const signingInput = `${header}.${body}`;
+    const expected = base64UrlEncode(
+      createHmac("sha256", getHmacSecret()).update(signingInput).digest(),
+    );
+    if (!timingSafeEqual(expected, sig)) return false;
+    // Re-check that the body still describes the same canonical event —
+    // protects against a valid JWS being replayed onto a different event.
+    let decoded: Record<string, unknown>;
+    try {
+      decoded = JSON.parse(
+        Buffer.from(body.replace(/-/g, "+").replace(/_/g, "/"), "base64").toString(),
+      );
+    } catch {
+      return false;
+    }
+    return (
+      decoded.planId === input.planId &&
+      decoded.type === input.type &&
+      decoded.payloadHash === input.payloadHash &&
+      (decoded.prevHash ?? null) === (input.prevHash ?? null)
+    );
+  }
+}
+
+/* --------------------------------------------------------------------
+ * Registry.
+ * ----------------------------------------------------------------- */
+
+function timingSafeEqual(a: string, b: string): boolean {
+  if (a.length !== b.length) return false;
+  // Simple constant-time compare over the hex/base64 strings.
+  let diff = 0;
+  for (let i = 0; i < a.length; i++) {
+    diff |= a.charCodeAt(i) ^ b.charCodeAt(i);
+  }
+  return diff === 0;
+}
+
+let cachedSigner: EventSigner | undefined;
+let cachedMode: SigningMode | undefined;
+
+export function resolveSigningMode(): SigningMode {
+  const raw = (process.env.EVENT_SIGNING_MODE ?? "hmac").toLowerCase();
+  if (raw === "eip712" || raw === "jws" || raw === "hmac") return raw;
+  return "hmac";
+}
+
+export function getEventSigner(): EventSigner {
+  const mode = resolveSigningMode();
+  if (cachedSigner && cachedMode === mode) return cachedSigner;
+  cachedMode = mode;
+  cachedSigner =
+    mode === "eip712"
+      ? new Eip712Signer()
+      : mode === "jws"
+        ? new JwsSigner()
+        : new HmacSigner();
+  return cachedSigner;
+}
+
+export function __resetSignerForTests(): void {
+  cachedSigner = undefined;
+  cachedMode = undefined;
+}
+
+/**
+ * Compatibility helper: the pre-PR-O signing scheme was
+ * `hmac_sha256(secret, canonical)` returned as hex. Keep it for
+ * verifying historical rows written before EVENT_SIGNING_MODE existed.
+ */
+export function legacyHmac(input: EventSignInput): string {
+  return createHmac("sha256", getHmacSecret())
+    .update(canonicalMessage(input))
+    .digest("hex");
+}
+
+/**
+ * Deterministic sha256 over the payload — re-exported so the bus
+ * doesn't have to import `crypto` directly.
+ */
+export function payloadHashOf(payload: unknown): string {
+  return createHash("sha256").update(JSON.stringify(payload)).digest("hex");
+}

orchestrator/tests/unit/eventSigner.test.ts

@@ -0,0 +1,187 @@
+/**
+ * PR O — EIP-712 / JWS event signatures (gap-analysis v2 §7.5 / §10.5).
+ *
+ * Covers:
+ *   - HMAC default mode (back-compat) — round-trip sign/verify
+ *   - JWS compact mode — valid signature, payload-tamper detection,
+ *     signature-tamper detection
+ *   - EIP-712 mode — round-trip via ethers wallet, tamper detection
+ *   - Mode switching via EVENT_SIGNING_MODE + getEventSigner()
+ *   - legacyHmac helper preserves the pre-PR-O signature shape
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from "@jest/globals";
+import { ethers } from "ethers";
+import {
+  getEventSigner,
+  resolveSigningMode,
+  legacyHmac,
+  __resetSignerForTests,
+  type EventSignInput,
+} from "../../src/services/eventSigner";
+
+const TEST_KEY = "0x" + "ab".repeat(32); // deterministic test wallet
+
+function makeInput(overrides: Partial<EventSignInput> = {}): EventSignInput {
+  return {
+    planId: "plan-x",
+    type: "transaction.created",
+    payloadHash: "a".repeat(64),
+    prevHash: null,
+    ...overrides,
+  };
+}
+
+describe("eventSigner — mode resolution", () => {
+  beforeEach(() => {
+    __resetSignerForTests();
+    delete process.env.EVENT_SIGNING_MODE;
+    delete process.env.ORCHESTRATOR_PRIVATE_KEY;
+  });
+
+  it("defaults to hmac when env var absent", () => {
+    expect(resolveSigningMode()).toBe("hmac");
+    expect(getEventSigner().mode).toBe("hmac");
+  });
+
+  it("honours eip712 / jws / hmac values", () => {
+    for (const mode of ["eip712", "jws", "hmac"] as const) {
+      __resetSignerForTests();
+      process.env.EVENT_SIGNING_MODE = mode;
+      expect(resolveSigningMode()).toBe(mode);
+      expect(getEventSigner().mode).toBe(mode);
+    }
+  });
+
+  it("falls through to hmac on unknown mode", () => {
+    process.env.EVENT_SIGNING_MODE = "bogus";
+    expect(resolveSigningMode()).toBe("hmac");
+  });
+});
+
+describe("eventSigner — HMAC round-trip", () => {
+  beforeEach(() => {
+    __resetSignerForTests();
+    process.env.EVENT_SIGNING_MODE = "hmac";
+    process.env.EVENT_BUS_HMAC_SECRET = "test-secret";
+  });
+
+  it("signs + verifies", async () => {
+    const signer = getEventSigner();
+    const input = makeInput();
+    const sig = await signer.sign(input);
+    expect(sig).toMatch(/^[0-9a-f]{64}$/);
+    expect(await signer.verify(input, sig)).toBe(true);
+  });
+
+  it("rejects a tampered payload hash", async () => {
+    const signer = getEventSigner();
+    const input = makeInput();
+    const sig = await signer.sign(input);
+    expect(
+      await signer.verify({ ...input, payloadHash: "b".repeat(64) }, sig),
+    ).toBe(false);
+  });
+
+  it("legacyHmac produces the same hex as the HMAC signer", async () => {
+    const input = makeInput();
+    const sig = await getEventSigner().sign(input);
+    expect(legacyHmac(input)).toBe(sig);
+  });
+});
+
+describe("eventSigner — JWS compact", () => {
+  beforeEach(() => {
+    __resetSignerForTests();
+    process.env.EVENT_SIGNING_MODE = "jws";
+    process.env.EVENT_BUS_HMAC_SECRET = "jws-secret";
+  });
+
+  it("produces header.body.sig shape", async () => {
+    const sig = await getEventSigner().sign(makeInput());
+    expect(sig.split(".")).toHaveLength(3);
+  });
+
+  it("round-trips sign/verify", async () => {
+    const signer = getEventSigner();
+    const input = makeInput();
+    expect(await signer.verify(input, await signer.sign(input))).toBe(true);
+  });
+
+  it("rejects a different event being presented with a valid sig", async () => {
+    const signer = getEventSigner();
+    const signed = await signer.sign(makeInput());
+    expect(
+      await signer.verify(makeInput({ type: "transaction.aborted" }), signed),
+    ).toBe(false);
+  });
+
+  it("rejects a truncated signature", async () => {
+    const signer = getEventSigner();
+    const sig = await signer.sign(makeInput());
+    expect(await signer.verify(makeInput(), sig.slice(0, -3))).toBe(false);
+  });
+});
+
+describe("eventSigner — EIP-712 (ethers wallet)", () => {
+  beforeEach(() => {
+    __resetSignerForTests();
+    process.env.EVENT_SIGNING_MODE = "eip712";
+    process.env.ORCHESTRATOR_PRIVATE_KEY = TEST_KEY;
+    process.env.CHAIN_138_CHAIN_ID = "138";
+  });
+
+  afterEach(() => {
+    delete process.env.ORCHESTRATOR_PRIVATE_KEY;
+  });
+
+  it("produces a 65-byte 0x-prefixed ECDSA signature", async () => {
+    const sig = await getEventSigner().sign(makeInput());
+    expect(sig).toMatch(/^0x[0-9a-fA-F]{130}$/);
+  });
+
+  it("verifies as the signing wallet", async () => {
+    const signer = getEventSigner();
+    const input = makeInput();
+    const sig = await signer.sign(input);
+    expect(await signer.verify(input, sig)).toBe(true);
+    // Recovered address should match the wallet derived from TEST_KEY.
+    const expectedAddress = new ethers.Wallet(TEST_KEY).address;
+    const recovered = ethers.verifyTypedData(
+      {
+        name: "CurrenciCombo",
+        version: "1",
+        chainId: 138,
+        verifyingContract:
+          process.env.NOTARY_REGISTRY_ADDRESS ??
+          "0x0000000000000000000000000000000000000000",
+      },
+      {
+        Event: [
+          { name: "planId", type: "string" },
+          { name: "eventType", type: "string" },
+          { name: "payloadHash", type: "bytes32" },
+          { name: "prevHash", type: "bytes32" },
+        ],
+      },
+      {
+        planId: input.planId,
+        eventType: input.type,
+        payloadHash: `0x${input.payloadHash}`,
+        prevHash: "0x" + "0".repeat(64),
+      },
+      sig,
+    );
+    expect(recovered.toLowerCase()).toBe(expectedAddress.toLowerCase());
+  });
+
+  it("rejects a signature for a different event", async () => {
+    const signer = getEventSigner();
+    const sig = await signer.sign(makeInput());
+    // Valid signature but rebound to a different event → fails because
+    // the recovered address won't be our wallet.
+    expect(
+      await signer.verify(makeInput({ type: "transaction.committed" }), sig),
+    ).toBe(false);
+  });
+});