Smart Banner Hub has launched the Clustrauth API, bringing NIST FIPS 204-compliant, quantum-safe document authentication directly to developers. The new REST API allows for programmatic signing of any file up to 50MB, utilizing a hybrid Ed25519 + ML-DSA cryptographic approach for both current and future security needs. Previously limited to Smart Banner Hub’s consumer platform at $24.99 per document, developers can now access this technology with subscription plans starting at $249 per month. “Post-quantum document authentication shouldn’t require a six-figure enterprise contract or a manual upload flow. The Clustrauth API puts NIST FIPS 204 cryptography directly into developers’ hands — three lines of code, a subscription that scales with you, verify forever. No sales calls, no onboarding, no surprise invoices,” explains Ashwin Spencer, Founder & CEO of Smart Banner Hub LLC.

Clustrauth API: NIST FIPS 204 Quantum-Safe Document Signing

This arrival is significant as current cryptographic methods are increasingly vulnerable to attacks from quantum computers, a threat anticipated to materialize within the next decade. The Clustrauth API distinguishes itself by offering a tiered subscription model, starting at $249 per month for 50 signatures, a stark contrast to traditional enterprise solutions. This accessibility is further underscored by the API’s design; developers can integrate the service with just three lines of code, receiving a Certificate ID with full cryptographic proof. Verification of these documents is permanently available and, crucially, free of charge.

Beyond basic signing, the API provides SHA3-256 document hashing for bit-level integrity verification and generates a downloadable Certificate of Authenticity PDF. Developers benefit from features like idempotency keys to prevent duplicate charges and a sandbox environment offering three free test signatures. Subscription tiers extend to a Business plan at $999/month with 250 signatures and an Enterprise option for custom volumes, each including unlimited free verification and permanent certificate storage. The API’s base URL is https://smartbannerhub.com/api/v1/clustrauth, and full documentation is available for immediate integration.

Ed25519 & ML-DSA Hybrid Signature Implementation

The escalating threat to current cryptographic standards has spurred innovation in post-quantum cryptography, and a key development lies in hybrid signature implementations. Rather than relying on a single algorithm, systems are now incorporating both classical and quantum-resistant methods for enhanced security. Smart Banner Hub’s Clustrauth API exemplifies this approach, utilizing a dual signature system combining Ed25519 with ML-DSA, a NIST FIPS 204-compliant algorithm. This “defense in depth” strategy ensures that even if one algorithm is compromised, the other continues to provide authentication.

Every document signed via the Clustrauth API benefits from this layered security, with both Ed25519 and ML-DSA/CRYSTALS-Dilithium employed to verify authenticity. Beyond the algorithms themselves, the system incorporates SHA3-256 document hashing, providing bit-level integrity verification across the entire file. Developers gain access to a downloadable Certificate of Authenticity PDF, offering tangible proof of authentication for their own customers. Importantly, verification of these signatures is offered free of charge and indefinitely, a significant departure from some enterprise solutions. The API’s technical specifications reveal support for any file type up to 50MB, authenticated via an API key.

The output includes a Certificate ID, the Certificate of Authenticity PDF, and a verification URL. A sandbox environment allows for three free test signatures, enabling developers to fully explore the API’s capabilities before committing to a subscription. Smart Banner Hub LLC was founded in March 2025, and has been named among leading post-quantum cryptography innovators by GlobalData alongside industry giants like Apple and Google.

Every document is signed with both Ed25519 (classical) and ML-DSA/CRYSTALS-Dilithium (post-quantum, NIST FIPS 204) – hybrid defense in depth.

Smart Banner Hub LLC

Developer Subscription Plans & Rate Limits

Smart Banner Hub LLC is challenging conventional wisdom surrounding post-quantum cryptography implementation with its newly launched Clustrauth API, offering developers a tiered subscription model designed for accessibility. Previously, the company’s quantum-safe signing capabilities were confined to its consumer platform, Quantum Auth Forge™, priced at $24.99 per document – a cost prohibitive for large-scale integration. Now, developers can leverage NIST FIPS 204-compliant cryptography within their own applications, starting at $249 per month. The API’s pricing structure is tiered to accommodate varying needs, with the ‘Developer’ plan providing 50 included signatures alongside a $5.00 per additional signature overage rate.

Businesses requiring higher volumes can opt for the ‘Business’ plan at $999 monthly, which includes 250 signatures and a reduced overage fee of $3.50. For organizations with substantial demands, a custom ‘Enterprise’ plan is available, offering tailored signature volumes and dedicated support. Importantly, all subscription levels feature unlimited free verification, permanent certificate storage, and access to a Certificate of Authenticity PDF for each signed document. Rate limits are also scaled by plan, ranging from 30 signatures per minute on the ‘Developer’ tier to 120/min for ‘Enterprise’ users.

API Technical Specifications & File Support

The Clustrauth API isn’t simply offering a future-proof solution; it’s delivering functional post-quantum security for developers today. Beyond the headline promise of NIST FIPS 204 compliance, the API’s technical specifications are geared towards seamless integration and broad compatibility. The system accommodates a wide range of file types, accepting anything up to 50MB, and offers flexible upload methods – form data or base64-encoded JSON – to suit diverse integration needs. Crucially, verification isn’t a paid feature; it’s “free, forever,” allowing developers to offer their users confidence in document authenticity without ongoing costs.

Permanent certificate storage is also included, ensuring retrievability of cryptographic proof at any time. Developers authenticate via an API key, submitting files to the /sign endpoint and receiving a Certificate ID, a process designed for speed and efficiency. Subscription tiers – Developer ($249/month), Business ($999/month), and Enterprise (custom pricing) – offer varying signature allowances and rate limits, scaling to accommodate different usage levels.