fipsign-sdk 0.8.0

Post-quantum signing SDK for Python — ML-DSA-65 (NIST FIPS 204)

fipsign-sdk

Post-quantum signing SDK for Python.

Signs and verifies any payload using ML-DSA-65 (NIST FIPS 204) — the post-quantum digital signature standard resistant to Shor's algorithm. Standardized by NIST in August 2024.

Not just for auth. Sign users, orders, documents, devices, events — any entity that needs a tamper-proof, quantum-resistant signature.

---

Install

pip install fipsign-sdk

For async support (httpx-based):

pip install fipsign-sdk[async]

---

Quick start

1. Create a free account at app.fipsign.dev — enter your email, verify the OTP code sent to your inbox.

2. In the dashboard, create a project, then create an API key inside that project. Save the key — it will not be shown again.

3. Use the key in your app:

from fipsign import PQAuth

pq = PQAuth("pqa_your_api_key")

---

sign() — Sign anything

The only required argument is sub — any string identifying the entity you want to sign. All other keyword arguments are stored in the payload and returned on verify. Cost: 1 token.

# Sign a user session
result = pq.sign("user_123", email="[e-mail]", role="admin", expires_in_seconds=3600)
token  = result.token
meta   = result.meta
usage  = result.usage

# Sign an order
result = pq.sign("order_456", amount=299.99, currency="USD", expires_in_seconds=300)

# Sign a document
result = pq.sign("doc_789", hash="sha256:abc...", signed_by="alice")

# Sign a device
result = pq.sign("device_iot_001", firmware="2.1.4")

# Monitor quota and token source
print(f"{usage.freeRemaining} free tokens remaining this month")
print(f"{usage.packRemaining} pack tokens remaining")
print(f"{usage.totalRemaining} total remaining")
print(f"charged from: {meta.source}")  # "free" | "pack" | "free+pack"

sign() response shape

SignResult
  .token   PQToken
               .payload    str   # base64 encoded payload
               .signature  str   # ML-DSA-65 signature
               .algorithm  str   # "ML-DSA-65"
               .issuedAt   int   # Unix timestamp
  .meta    SignMeta
               .algorithm        str
               .standard         str   # "NIST FIPS 204"
               .quantumResistant bool
               .expiresIn        int   # seconds
               .issuedFor        str   # your developer account email
               .projectId        str
               .tokenCost        int   # always 1
               .source           str   # "free" | "pack" | "free+pack"
  .usage   SignUsage
               .freeRemaining  int
               .packRemaining  int
               .totalRemaining int
               .month          str   # e.g. "2026-05"

---

verify() — Verify a token

Never raises. Returns a VerifyResult with valid=False and an error message on any failure. Cost: 1 token.

result = pq.verify(token)

if not result.valid:
    raise PermissionError(result.error)

print(result.payload["sub"])   # "user_123"
print(result.payload["exp"])   # expiry timestamp (Unix)
print(result.payload["iat"])   # issued at timestamp (Unix)
# All custom fields passed to sign() are in payload too

---

revoke() — Revoke a token

Immediately and permanently invalidates a token. Future verify() calls will reject it even if the signature is valid and it hasn't expired. Cost: 1 token.

pq.revoke(token, "user logged out")
pq.revoke(token, "order cancelled")
pq.revoke(token, "suspicious activity detected")

Revoking an already-revoked token returns success without consuming an extra token — the operation is idempotent.

Note: Calling revoke() on an already-expired token raises PQAuthError(code="API_ERROR", status=400).

---

Flask middleware

Reads Authorization: Bearer <token> and attaches the decoded payload to flask.g.fipsign_user. Returns 401 automatically on invalid tokens.

from flask import Flask, g
from fipsign import PQAuth, flask_middleware

app  = Flask(__name__)
pq   = PQAuth("pqa_your_api_key")
auth = flask_middleware(pq)

@app.route("/login", methods=["POST"])
def login():
    import base64, json
    # authenticate user however you like, then:
    result  = pq.sign(user.id, email=user.email, role=user.role, expires_in_seconds=3600)
    encoded = base64.b64encode(json.dumps(result.token.to_dict()).encode()).decode()
    return {"token": encoded}

@app.route("/logout", methods=["POST"])
def logout():
    import base64, json
    from flask import request
    from fipsign.types import PQToken
    header = request.headers.get("Authorization", "")
    if header.startswith("Bearer "):
        token = PQToken.from_dict(json.loads(base64.b64decode(header[7:]).decode()))
        pq.revoke(token, "user logged out")
    return {"success": True}

@app.route("/api/profile")
@auth
def profile():
    return {"user": g.fipsign_user}

---

FastAPI middleware

from fastapi import FastAPI, Depends
from fipsign import PQAuth, fastapi_middleware

app          = FastAPI()
pq           = PQAuth("pqa_your_api_key")
require_auth = fastapi_middleware(pq)

@app.get("/api/profile")
def profile(user=Depends(require_auth)):
    return {"sub": user["sub"], "role": user.get("role")}

---

Async client

All methods are identical to PQAuth but async. Use in FastAPI, aiohttp, or any asyncio-based application. Requires pip install fipsign-sdk[async].

from fipsign.async_client import AsyncPQAuth

async with AsyncPQAuth("pqa_your_api_key") as pq:
    result = await pq.sign("user_123", role="admin", expires_in_seconds=3600)
    v      = await pq.verify(result.token)
    print(v.valid, v.payload["sub"])

    # CA operations work the same way
    cert = await pq.ca.issue(
        subject="device-serial-00123",
        public_key=device_public_key_b64,
        expires_in_seconds=365 * 24 * 60 * 60,
    )
    crl = await pq.ca.get_crl()
    if pq.ca.is_cert_revoked(cert.meta.certId, crl.crl):
        raise PermissionError("Device revoked")

---

usage() — Token balance

Free tokens reset on the 1st of each month (UTC). Pack tokens never expire and accumulate across purchases. No token cost.

u = pq.usage()

# Current balance
print(f"Month: {u.current.month}")
print(f"Free:  {u.current.freeRemaining} / {u.current.freeLimit}")
print(f"Used:  {u.current.freeUsed} this month")
print(f"Pack:  {u.current.packRemaining}")
print(f"Total: {u.current.totalRemaining}")
print(f"Account: {u.developer['email']}")

# 6-month history (always 6 entries, months with no activity show 0)
for entry in u.monthlyHistory:
    print(f"{entry.month}: {entry.tokensUsed} used ({entry.fromFree} free + {entry.fromPack} pack)")

# Purchased packs
from datetime import datetime
for pack in u.packs:
    date = datetime.fromtimestamp(pack.purchasedAt).strftime("%Y-%m-%d")
    print(f"{pack.packType}: {pack.tokensPurchased} tokens — {date}")

---

webhooks — Real-time notifications

Events: token.signed · token.rejected · token.revoked · limit.warning · limit.reached

# Register
result = pq.webhooks.register(
    url="https://yourapp.com/webhooks/fipsign",
    events=["limit.warning", "limit.reached", "token.revoked"],
)
print(result.webhook.secret)  # store this — shown only once

# Send a test event to confirm your endpoint is reachable
pq.webhooks.test()

# Get current config (secret is never returned after registration)
config = pq.webhooks.get()
if config.webhook is None:
    print("No webhook configured")

# Delete
pq.webhooks.delete()

Re-registering an existing webhook updates the URL and events but preserves the original secret. To rotate the secret, delete and re-register.

Verifying incoming webhook requests

Each incoming POST includes the headers X-PQAuth-Event, X-PQAuth-Signature (sha256=...), and X-PQAuth-Timestamp.

from fipsign.middleware import verify_webhook_signature

# Flask
@app.route("/webhooks/fipsign", methods=["POST"])
def webhook():
    from flask import request
    sig = request.headers.get("X-PQAuth-Signature", "")
    if not verify_webhook_signature(request.data, sig, FIPSIGN_WEBHOOK_SECRET):
        return "Invalid signature", 401

    event = request.json
    match event["event"]:
        case "limit.warning":
            print(f"Usage warning — {event['data']['freeRemaining']} free tokens left")
        case "limit.reached":
            print(f"Limit reached — pack remaining: {event['data']['packRemaining']}")
        case "token.revoked":
            print(f"Token revoked for sub: {event['data']['sub']}")

    return "ok", 200


# FastAPI
from fastapi import Request
@app.post("/webhooks/fipsign")
async def webhook(request: Request):
    body = await request.body()
    sig  = request.headers.get("X-PQAuth-Signature", "")
    if not verify_webhook_signature(body, sig, FIPSIGN_WEBHOOK_SECRET):
        raise HTTPException(status_code=401, detail="Invalid signature")

    event = await request.json()
    # handle event["event"] ...
    return "ok"

---

ca — Certificate Authority

Issue post-quantum certificates for devices, services, or any entity that needs a tamper-proof identity. Built on ML-DSA-65 — the same algorithm used for token signing.

Typical use case: A manufacturer of smart locks, IoT sensors, or logistics devices creates a CA root once per project from the dashboard. For each device manufactured, the server calls ca.issue() with the device's public key. The device stores its certificate. Runtime verification happens entirely offline — no API call needed.

Setup: Create a project in the dashboard, then click "Create CA" inside that project. Choose a certificate format:

• PQCert — FIPSign's native JSON format. Certificates are JSON objects (dataclasses in Python). Simpler to work with in pure Python environments.
• X.509 — Standard X.509 v3 PEM certificates signed with ML-DSA-65 (OID 2.16.840.1.101.3.4.3.18, RFC 9881). Compatible with OpenSSL 3.5+, standard PKI tooling, and enterprise infrastructure.

The format is chosen once at CA creation and applies to all certificates issued by that CA. One CA per project — you cannot mix formats within a project.

Save the root certificate now. It is shown only once at CA creation. Without it, offline certificate verification is not possible. Store it in a secrets manager or secure file — treat it like a private key.

When you call ca.issue() or other CA methods, the SDK automatically uses the CA associated with the project that owns the API key. No caId parameter needed.

---

Device key pair generation

The Python SDK does not include a generate_key_pair() function. Device key pairs are generated using the JavaScript SDK at provisioning time:

import { generateKeyPair } from 'fipsign-sdk'

const { publicKey, secretKey } = await generateKeyPair()
// store secretKey securely on the device — never send it to the server
// pass publicKey to ca.issue() to obtain a certificate

Then call ca.issue() from Python with the publicKey:

result = pq.ca.issue(
    subject="device-serial-00123",
    public_key=public_key_from_js,   # base64 ML-DSA-65 public key
    expires_in_seconds=365 * 24 * 60 * 60,
)

Alternatively, if you need to generate key pairs in Python directly, use pyca/cryptography >= 44.0.0:

from cryptography.hazmat.primitives.asymmetric.mldsa import MLDSA65, generate_private_key
from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat
import base64

private_key = generate_private_key(MLDSA65())
public_key  = private_key.public_key()
pub_bytes   = public_key.public_bytes(Encoding.Raw, PublicFormat.Raw)
pub_b64     = base64.b64encode(pub_bytes).decode()

# pass pub_b64 to ca.issue()

---

ca.issue() — Issue a certificate

Issue a certificate signed by your project's CA. Cost: 1 token.

expires_in_seconds is required and must be between 60 seconds (minimum) and 157,680,000 seconds (5 years maximum).

The type of result.certificate depends on the CA format:

• PQCert CA — certificate is a PQCert dataclass with fields .id, .caId, .signature, .expiresAt, etc.
• X.509 CA — certificate is a PEM string ("-----BEGIN CERTIFICATE-----\n..."). Certificate metadata is available in meta.

# PQCert CA
result = pq.ca.issue(
    subject="device-serial-00123",
    public_key=device_public_key_b64,
    expires_in_seconds=365 * 24 * 60 * 60,
    meta={"model": "lock-v2", "batch": "2026-05"},  # optional, max 10 keys
)

# result.certificate is a PQCert dataclass
print(result.certificate.id)         # cert_...
print(result.certificate.caId)       # ca_...
print(result.certificate.expiresAt)  # Unix timestamp
print(result.meta.certId)            # same as certificate.id


# X.509 CA
result = pq.ca.issue(
    subject="device-serial-00123",
    public_key=device_public_key_b64,
    expires_in_seconds=365 * 24 * 60 * 60,
)

# result.certificate is a PEM string
print(type(result.certificate))   # <class 'str'>
print(result.certificate[:27])    # "-----BEGIN CERTIFICATE-----"
print(result.meta.certId)         # cert_... — use this for revocation
print(result.meta.caId)           # ca_...
print(result.meta.expiresAt)      # Unix timestamp

Note for X.509: Store meta.certId alongside the PEM certificate. You will need it for ca.revoke_cert() and ca.is_cert_revoked().

---

ca.verify_cert() — Offline certificate verification

Not available in the Python SDK. Offline verification requires ML-DSA-65 local cryptography.

For PQCert CAs, use the JavaScript SDK:

import rootCert from './root-cert.json' assert { type: 'json' }
const result = fipsign.ca.verifyCert(deviceCert, rootCert)
if (!result.valid) return reject(result.error)

For X.509 CAs, use pyca/cryptography >= 44.0.0 directly:

from cryptography import x509
from cryptography.hazmat.primitives.asymmetric.mldsa import MLDSA65

root_cert = x509.load_pem_x509_certificate(root_pem.encode())
leaf_cert = x509.load_pem_x509_certificate(leaf_pem.encode())
root_pub  = root_cert.public_key()

# Raises InvalidSignature on failure, returns None on success
root_pub.verify(leaf_cert.signature, leaf_cert.tbs_certificate_bytes, MLDSA65())

For real-time server-side status checks, use ca.get_cert() from Python — it returns the live revocation status without needing the root certificate.

---

ca.is_cert_revoked() — Check revocation offline

Check if a certificate appears in a CRL. Offline — pass the result of ca.get_crl(). Works for both PQCert and X.509 formats.

Accepts either a PQCert object (for PQCert CAs) or a certId string (for X.509 CAs or when you only have the ID). The certId is returned in meta.certId from ca.issue().

crl_result = pq.ca.get_crl()

# PQCert CA — pass the PQCert dataclass
if pq.ca.is_cert_revoked(device_cert, crl_result.crl):
    raise PermissionError("Device certificate has been revoked")

# X.509 CA — pass the certId string from meta
if pq.ca.is_cert_revoked(meta.certId, crl_result.crl):
    raise PermissionError("Device certificate has been revoked")

# certId string also works for PQCert CAs
if pq.ca.is_cert_revoked(result.meta.certId, crl_result.crl):
    raise PermissionError("Device certificate has been revoked")

---

ca.get_crl() — Get the Certificate Revocation List

Fetch the current CRL for your project's CA. Free — no token cost. Works for both PQCert and X.509 formats.

Use get_crl() when you need to verify revocation in bulk — download the list once and check multiple certificates against it locally using is_cert_revoked(). For checking the status of a single certificate in real time (e.g. before a high-value transaction), use get_cert() instead.

result = pq.ca.get_crl()

print(f"CA: {result.subject}")
print(f"Format: {result.format}")       # "pqcert" or "x509"
print(f"{len(result.crl)} revoked certificates")

from datetime import datetime
for entry in result.crl:
    # entry.reason may be None if no reason was provided at revocation time
    ts = datetime.fromtimestamp(entry.revokedAt).isoformat()
    print(f"{entry.certId} — {ts} — {entry.reason or 'no reason'}")

For X.509 CAs, the CRL is signed with ML-DSA-65 by the CA private key. The raw signed object (including signature) is available in result.raw if you need it for verification.

---

ca.get_cert() — Get a certificate by ID

Retrieve a certificate and its current real-time status. Use this for single certificate checks before high-value operations. Free — no token cost. Works for both PQCert and X.509 formats.

result = pq.ca.get_cert("cert_...")

print(result.status.revoked)    # bool
print(result.status.expired)    # bool
print(result.status.revokedAt)  # Unix timestamp or None
print(result.status.expiresAt)  # Unix timestamp

# For PQCert CAs, result.certificate is a PQCert dataclass
# For X.509 CAs, result.certificate is a PEM string

---

ca.revoke_cert() — Revoke a certificate

Revoke a certificate immediately. It will appear in the CRL from this point on. Cost: 1 token.

# PQCert CA — use certificate.id
pq.ca.revoke_cert(device_cert.id, "device decommissioned")

# X.509 CA — use meta.certId from ca.issue()
pq.ca.revoke_cert(meta.certId, "device reported stolen")

# certId string works for both formats
pq.ca.revoke_cert("cert_...", "device decommissioned")

---

Full device lifecycle — PQCert

from fipsign import PQAuth

pq = PQAuth("pqa_your_api_key")

# 1. Factory: generate key pair using the JS SDK, store secretKey on device
# 2. Factory: issue a certificate for the device
result = pq.ca.issue(
    subject="lock-serial-00123",
    public_key=device_public_key_b64,    # generated by JS SDK on device
    expires_in_seconds=365 * 24 * 60 * 60,
    meta={"model": "lock-v3", "batch": "2026-05"},
)
certificate = result.certificate   # PQCert dataclass — store on device

# 3. At runtime: real-time revocation check (single cert, server-side)
status = pq.ca.get_cert(certificate.id)
if status.status.revoked:
    raise PermissionError("Device revoked")

# 4. At runtime: bulk revocation check (offline, from cached CRL)
crl_result = pq.ca.get_crl()
if pq.ca.is_cert_revoked(certificate, crl_result.crl):
    raise PermissionError("Device revoked")

# 5. Decommission: revoke the certificate
pq.ca.revoke_cert(certificate.id, "device decommissioned")

---

Full device lifecycle — X.509

from fipsign import PQAuth

pq = PQAuth("pqa_your_api_key")

# root_pem — the PEM string shown once at CA creation, stored securely
root_pem = os.environ["FIPSIGN_ROOT_CERT_PEM"]

# 1. Factory: generate key pair using the JS SDK, store secretKey on device
# 2. Factory: issue a certificate for the device
result  = pq.ca.issue(
    subject="lock-serial-00123",
    public_key=device_public_key_b64,    # generated by JS SDK on device
    expires_in_seconds=365 * 24 * 60 * 60,
)
cert_pem = result.certificate    # PEM string — store on device
cert_id  = result.meta.certId   # store alongside the PEM

# 3. At runtime: offline signature verification (no API call)
#    Requires pyca/cryptography >= 44.0.0
from cryptography import x509
from cryptography.hazmat.primitives.asymmetric.mldsa import MLDSA65

root_cert = x509.load_pem_x509_certificate(root_pem.encode())
leaf_cert = x509.load_pem_x509_certificate(cert_pem.encode())
root_cert.public_key().verify(
    leaf_cert.signature,
    leaf_cert.tbs_certificate_bytes,
    MLDSA65()
)  # raises InvalidSignature on failure

# 4. At runtime: bulk revocation check (offline, from cached CRL)
crl_result = pq.ca.get_crl()
if pq.ca.is_cert_revoked(cert_id, crl_result.crl):
    raise PermissionError("Device revoked")

# 5. Decommission: revoke the certificate using certId
pq.ca.revoke_cert(cert_id, "device decommissioned")

---

Error handling

verify() never raises — it returns VerifyResult(valid=False, error="...") on any failure. All other methods raise PQAuthError on failure.

from fipsign import PQAuth, PQAuthError

try:
    result = pq.sign("user_123")
except PQAuthError as err:
    match err.code:
        case "INVALID_API_KEY":  # key missing or doesn't start with pqa_
            ...
        case "API_ERROR":        # server returned an error (check err.status)
            ...
        case "TIMEOUT":          # request exceeded timeout (default: 10s)
            ...
        case "NETWORK_ERROR":    # connection failed
            ...
        case "MISSING_SUB":      # sign() called without sub
            ...
    print(err.code, err.message, err.status)

Common err.status values for API_ERROR:

• 400 — invalid parameters (e.g. expires_in_seconds out of range, invalid public key)
• 401 — API key missing or invalid
• 404 — resource not found (e.g. no active CA for the project)
• 409 — conflict (e.g. revoking an already-revoked certificate)
• 429 — token quota exhausted or rate limit exceeded

---

Token quota

Every account gets 10,000 free tokens per month, reset on the 1st (UTC). Unused free tokens do not carry over. Additional tokens are available as non-expiring packs, purchased from the dashboard.

Each of these operations costs 1 token: signing (sign()), verification (verify()), revocation (revoke()), certificate issuance (ca.issue()), and certificate revocation (ca.revoke_cert()). Checking usage (usage()), fetching the public key, and all CA read operations (ca.get_crl(), ca.get_cert()) are free.

---

Rate limits

300 requests per minute per API key on sign(), verify(), and revoke(). On excess the API returns HTTP 429.

CA operations (ca.issue(), ca.revoke_cert()) are rate limited at 300 requests per minute per API key, consistent with signing and verification. Read operations (ca.get_crl(), ca.get_cert()) are not rate limited.

Token quota and rate limits are separate controls — check the error message to distinguish them:

• "Rate limit exceeded" → back off and retry with exponential backoff
• "Token limit reached" → purchase a pack from the dashboard, retrying won't help

---

Constructor options

pq = PQAuth(
    api_key="pqa_...",                    # required — must start with pqa_
    base_url="https://api.fipsign.dev",   # optional, override for self-hosting
    timeout=10,                           # optional, seconds (default: 10)
)

Option	Type	Default	Description
api_key	str	—	Required. From the dashboard. Raises INVALID_API_KEY immediately if not prefixed with pqa_.
base_url	str	https://api.fipsign.dev	Override for local dev or self-hosted instances.
timeout	float	10	Request timeout in seconds. Raises TIMEOUT on exceeded.
session	requests.Session	—	Custom session (e.g. for proxies or custom TLS).

---

Why ML-DSA-65?

JWT with RS256/ES256 and standard OAuth tokens use ECDSA or RSA — both vulnerable to Shor's algorithm running on a sufficiently powerful quantum computer. ML-DSA-65 is based on the hardness of lattice problems (Module-LWE / Module-SIS), which have no known quantum speedup. It was standardized by NIST in August 2024 as FIPS 204.

---

Integration tests

FIPSIGN_API_KEY=pqa_your_key \
WEBHOOK_URL=https://webhook.site/your-uuid \
WEBHOOK_SITE_TOKEN=your-uuid \
python tests/test_sdk.py

---

Links

• Dashboard: app.fipsign.dev
• Developer guide: fipsign.dev/guide
• API status: api.fipsign.dev/health
• JS SDK: npmjs.com/package/fipsign-sdk
• NIST FIPS 204: csrc.nist.gov/pubs/fips/204/final