eden/apps/api/test/signature-hash-chain.spec.ts

import { describe, expect, it } from "vitest";
import { canonicalJson, computeEventHash, signaturesRepo } from "@eden/database";

const { ENVELOPE_STATUSES, ENVELOPE_TRANSITIONS, assertEnvelopeTransition, InvalidEnvelopeTransitionError } =
  signaturesRepo;
import { generateOtpCode, hashOtpCode } from "../src/signatures/otp.js";
import { generateSignerToken, hashSignerToken } from "../src/signatures/token.js";

describe("hash-chain canonicalization — pure functions, no DB", () => {
  it("key order never changes the canonical string (defends against Postgres jsonb key reordering)", () => {
    const a = canonicalJson({ b: 1, a: 2, metadata: { z: 1, y: 2 } });
    const b = canonicalJson({ a: 2, b: 1, metadata: { y: 2, z: 1 } });
    expect(a).toBe(b);
  });

  it("undefined values canonicalize to null, never dropped", () => {
    expect(canonicalJson({ a: undefined })).toBe('{"a":null}');
  });

  it("computeEventHash chains — same inputs always produce the same hash (deterministic, reproducible verification)", () => {
    const fields = { eventType: "TEST", metadata: { x: 1 } };
    const h1 = computeEventHash("", fields);
    const h2 = computeEventHash("", fields);
    expect(h1).toBe(h2);
    expect(h1).toMatch(/^[a-f0-9]{64}$/);
  });

  it("a different previous hash changes the result — this is what makes the chain tamper-evident", () => {
    const fields = { eventType: "TEST" };
    const h1 = computeEventHash("aaa", fields);
    const h2 = computeEventHash("bbb", fields);
    expect(h1).not.toBe(h2);
  });
});

describe("envelope state machine — pure, no DB", () => {
  it("every terminal status has no outgoing transitions", () => {
    for (const terminal of ["COMPLETED", "DECLINED", "EXPIRED", "CANCELLED", "SUPERSEDED", "ERROR"] as const) {
      expect(ENVELOPE_TRANSITIONS[terminal]).toEqual([]);
    }
  });

  it("SENT -> SIGNED is a valid direct jump (per-signer granularity never mirrored on the envelope)", () => {
    expect(() => assertEnvelopeTransition("SENT", "SIGNED")).not.toThrow();
  });

  it("rejects an invalid transition (e.g. DRAFT straight to SIGNED)", () => {
    expect(() => assertEnvelopeTransition("DRAFT", "SIGNED")).toThrow(InvalidEnvelopeTransitionError);
  });

  it("rejects going backward out of a terminal state", () => {
    expect(() => assertEnvelopeTransition("COMPLETED", "DRAFT")).toThrow(InvalidEnvelopeTransitionError);
  });

  it("every status in ENVELOPE_STATUSES has an entry in the transition table (no silently-forgotten state)", () => {
    for (const status of ENVELOPE_STATUSES) {
      expect(ENVELOPE_TRANSITIONS[status]).toBeDefined();
    }
  });
});

describe("OTP — pure crypto, no DB", () => {
  it("generateOtpCode always returns 6 digits, zero-padded", () => {
    for (let i = 0; i < 50; i++) {
      const code = generateOtpCode();
      expect(code).toMatch(/^\d{6}$/);
    }
  });

  it("hashOtpCode is deterministic for the same code+secret, and never returns the plaintext code", () => {
    const secret = "a".repeat(32);
    const h1 = hashOtpCode("123456", secret);
    const h2 = hashOtpCode("123456", secret);
    expect(h1).toBe(h2);
    expect(h1).not.toContain("123456");
    expect(h1).toMatch(/^[a-f0-9]{64}$/);
  });

  it("a different secret produces a different hash for the same code (rainbow-table resistance depends on this)", () => {
    const h1 = hashOtpCode("123456", "a".repeat(32));
    const h2 = hashOtpCode("123456", "b".repeat(32));
    expect(h1).not.toBe(h2);
  });
});

describe("secure signer token — pure crypto, no DB", () => {
  it("generateSignerToken returns 64 hex chars (32 bytes/256 bits)", () => {
    const token = generateSignerToken();
    expect(token).toMatch(/^[a-f0-9]{64}$/);
  });

  it("two generated tokens are never equal", () => {
    expect(generateSignerToken()).not.toBe(generateSignerToken());
  });

  it("hashSignerToken is deterministic and never returns the plaintext token", () => {
    const token = generateSignerToken();
    const hash = hashSignerToken(token);
    expect(hash).not.toBe(token);
    expect(hashSignerToken(token)).toBe(hash);
  });
});