A post-quantum cryptography patent is a patent or published application directed to cryptographic inventions built to withstand attack by a large-scale quantum computer. The motivation is concrete: a sufficiently powerful quantum computer running Shor's algorithm would break the public-key cryptography — RSA and elliptic-curve — that secures most of today's internet, so the field is racing to replace those schemes with quantum-resistant ones. The key distinction for reading these patents is what they can and cannot claim. The flagship post-quantum algorithms are now open public standards, which means a PQC patent typically does not claim the standardized algorithm itself. It claims something around the algorithm: a hardware implementation, a key-management or key-establishment scheme, a way to migrate an installed base from classical to quantum-safe cryptography, or a system that integrates a quantum-resistant primitive into a product.

The standards are the anchor. In August 2024 the National Institute of Standards and Technology finalized its first three post-quantum standards, and they define the algorithms the patents are built around. FIPS 203 specifies ML-KEM, a key-encapsulation mechanism. NIST's own description states the role and the security basis precisely.

A key-encapsulation mechanism (KEM) is a set of algorithms that, under certain conditions, can be used by two parties to establish a shared secret key over a public channel. ... This standard specifies a key-encapsulation mechanism called ML-KEM. The security of ML-KEM is related to the computational difficulty of the Module Learning with Errors problem. At present, ML-KEM is believed to be secure, even against adversaries who possess a quantum computer.— NIST FIPS 203 (Module-Lattice-Based Key-Encapsulation Mechanism Standard), source

Two companion standards round out the set. FIPS 204 specifies ML-DSA, a module-lattice-based digital-signature algorithm that, per NIST, "is believed to be secure, even against adversaries in possession" of a quantum computer; signatures "detect unauthorized modifications to data and ... authenticate the identity of the signatory." FIPS 205 specifies SLH-DSA, "the stateless hash-based digital signature algorithm," which NIST notes "is based on SPHINCS+, which was selected for standardization as part of the NIST Post-Quantum" project. ML-KEM derives from the Kyber submission and ML-DSA from Dilithium. Because these specifications are public and royalty-considerations were part of NIST's selection process, the algorithms themselves are meant to be implementable by anyone — which is exactly why patent activity concentrates on the surrounding engineering rather than the core math.

What a real PQC patent claims

Consider the granted patent US11533175B1, "Systems and methods for post-quantum cryptography on a smartcard," assigned to Wells Fargo Bank, N.A., with a January 30, 2020 priority date and a December 20, 2022 grant. Its independent claim 1 reads: "A system for post-quantum cryptography (PQC) comprising a PQC smartcard, wherein the PQC smartcard comprises: PQC cryptographic algorithm selection circuitry that selects a PQC cryptographic technique from a set of PQC cryptographic techniques for encrypting the data; and PQC cryptographic circuitry that encrypts data based on a generated set of PQC encryption attributes and the PQC cryptographic technique." Note what is and is not claimed. The claim is not directed to a lattice algorithm; it is directed to a smartcard architecture with selection circuitry that picks a PQC technique from a set, and cryptographic circuitry that performs the encryption. The CPC placement confirms the reading: the patent is classified under G06F 21/602, "Providing cryptographic facilities or services" on a computing device, rather than under the H04L 9 communications-protocol family. The invention, as claimed, is the on-card cryptographic system, with the choice of post-quantum algorithm left open — which is precisely the kind of implementation-and-integration coverage that the public-standard model channels patent filings toward.

The migration layer is where the filings cluster

Beyond device implementations, a large share of PQC patent activity is directed at the transition problem: how a deployed system moves off classical cryptography without manual rework. The DigiCert publication cluster covered elsewhere on this site is a clear illustration. US20260113205A1, "Seamlessly Transitioning to Post-Quantum Cryptography (PQC) in Digital Certificate Management," is directed to automatically moving an end entity from a current cryptography scheme over one certificate chain to a new scheme over an alternate chain when a certificate is up for reissue. US20250373411A1 is directed to protecting documents already signed with a classical algorithm by re-signing their hash with a PQC private key — wrapping a quantum-vulnerable signature in a quantum-resistant one. And US20250371170A1 is directed to tracking the one-time signatures of stateful hash-based schemes — the Leighton-Micali (LMS) and extended Merkle Signature (XMSS) constructions — on a distributed ledger so that a one-time key is never reused, the central operational hazard of stateful hash-based signatures (a family related to the stateless SLH-DSA of FIPS 205). These are applications, not grants, and their issued scope will be whatever an examiner allows; labeled correctly, they show where the inventive effort sits.

The throughline for reading any "post-quantum patent" headline is the same. The algorithm is probably a public NIST standard, so the patent is almost certainly claiming something else: a hardware path, a key-establishment or key-management scheme, a certificate-migration mechanism, or a hybrid construction that runs a classical and a post-quantum scheme together during the transition. Read the independent claim to find which, check whether the record is a granted patent or a published application, and note the priority date — in a field moving as fast as the PQC standardization timeline, the date that fixes the prior art is often the most load-bearing fact on the page.