We made a digital banking core ready for post-quantum cryptography, with swappable encryption, hybrid ECC and NIST ML-DSA signatures, and automated key rotation. The core now has 100% NIST alignment, and there was no service downtime during the change.
Industry: FinTech & Financial ServicesService: SaaS & SoftwareUpdated
Overview
The challenge
The client's Series-C banking core used standard elliptic curve cryptography (ECC). It is secure today, but future quantum computers running Shor's algorithm could break it. That leaves the bank open to "harvest now, decrypt later" (HNDL) attacks.
Partners had started asking about post-quantum readiness during due diligence. Changing the cryptography meant replacing hard-coded libraries in a core that had to stay available 24/7.
Attackers can capture encrypted transaction data today and decrypt it once quantum computers are powerful enough.
Business partners flagged the lack of post-quantum readiness as a long-term risk during due diligence.
Replacing hard-coded crypto libraries in live production put the core's 24/7 availability at risk.
The solution
An internal abstraction layer separates application logic from the cryptographic primitives, so algorithms can be swapped in configuration.
Each transaction is signed twice, with ECC and with NIST ML-DSA, so it stays protected even if one algorithm is broken.
An automated rotation policy refreshes keys across cloud services without affecting p99 transaction times.
Before and after
Before
Code rewrite
Hard-coded ECC meant refactoring each service by hand to change a security primitive.
After
Configuration change
New algorithms such as Kyber and Dilithium are added through a central layer with no code changes.
Before
Vulnerable
Exposed to HNDL attacks and to today's signature schemes becoming obsolete.
After
NIST-gated
Hybrid mode adds post-quantum protection now while still supporting older systems.
Before
Maintenance windows
Re-encrypting the key database needed core service restarts and downtime.
After
Rolling updates
Cloud-based rolling updates support several key versions at once, which kept uptime at 100%.
Key features
Hand-tuned assembly code for the NIST algorithms keeps authentication overhead low, even on mobile devices.
Business impact
Sub-5ms response time
Post-quantum entropy comes from FIPS 140-3 Level 3 hardware security modules.
Business impact
100% HSM-sourced entropy
Every transaction signature carries a key version tag, so past transactions can be audited consistently.
Business impact
Verifiable control
Results
100% Ready for future needs
100% of core authentication services now use NIST-standard post-quantum primitives.
Before: CoupledAfter: Agile
75% Performance Gain
Overhead stayed under 5ms, even with hybrid post-quantum signatures.
Before: > 20msAfter: < 5ms
0.0% Service Downtime
Key rotation ran across all digital assets without logging out a single customer.
Before: 99.9%After: 100.0%
Faster delivery
Reusing these tested components cut the setup work, so we launched sooner and put our effort into migrating the banking core itself.
Our tested wrapper added ML-DSA signing alongside the existing ECC signatures without changes to application code.
A reusable crypto-agility module provided the configuration-driven algorithm switching at the heart of the abstraction layer.
An existing monitoring platform checked the health of the entropy coming from the hardware security modules.
Pre-built FinOps controls kept cloud costs in check while key rotation ran across services.
Trust and control
The modular design lets the client move to new algorithms, such as NIST Round 5, with a simple configuration update.
CRYPTO-AGILEAligned with NIST FIPS 203 and 204, to meet upcoming SEC and GDPR requirements on quantum risk.
NIST-ALIGNEDKey rotation runs on cloud automation, with mTLS and hardware-backed identity for every worker node.
CONTROLLED ACCESSThe client owns 100% of the abstraction layer and the integration scripts once the work is complete.
100% OWNEDWe added a cryptographic abstraction layer so algorithms can be swapped in configuration instead of code. Transactions are now signed with both ECC and NIST ML-DSA, and keys rotate automatically from hardware security modules. All core authentication services moved to NIST-standard post-quantum primitives, giving 100% NIST alignment.
The migration ran with zero service downtime. Rolling cloud updates supported several key versions at once, so the core never needed the restarts and maintenance windows that re-encrypting keys used to require. Key rotation covered all digital assets without logging out a single customer.
Authentication overhead stayed under 5ms with hybrid signatures, compared with more than 20ms before, a 75% performance gain. We used hand-tuned assembly code for the NIST algorithms to keep the extra work small, including on mobile devices. Transaction times at p99 were not affected by key rotation.
If your platform depends on hard-coded RSA or ECC, we can help you plan a hybrid migration that keeps services running throughout.