THE QUANTUM INTELLIGENCER

Post-Quantum Readiness of the Internet: 2026 Measurement Study In Plain English: This study checks how ready websites are for the future threat of quantum computers, which could break current online security. Researchers looked at over 32,000 websites to see if they’re using new, quantum-resistant security methods. They found that while many sites are upgrading parts of their security, none are using quantum-safe certificates, which could allow hackers to forge identities in the future. This matters because sensitive data sent today could be decrypted later by quantum attackers. Without fixing this gap, even secure-looking websites may not be truly safe in the long run. Summary: The paper presents a comprehensive measurement study assessing the readiness of Internet domains for the post-quantum era, analyzing 32,011 domains across various sectors. It focuses on TLS deployments, examining protocol versions, cipher suites, key exchange mechanisms, and digital certificates. Despite growing awareness of quantum threats, the study reveals a fragmented transition: 15.70% of domains still rely on TLS 1.2, a protocol lacking support for modern cryptographic agility, with particularly high persistence in critical sectors like banking and government. While 49.3% of domains support hybrid post-quantum key exchanges—combining classical (e.g., X25519) with post-quantum (e.g., MLKEM768) algorithms—50.7% continue to use purely classical key exchange, indicating incomplete progress. A more alarming finding is the complete absence of hybrid post-quantum certificates, with 0% adoption observed across all domains. This is a critical gap because while hybrid key exchange protects data confidentiality, the lack of quantum-resistant authentication leaves systems vulnerable to attacks such as certificate forgery. An adversary with a quantum computer could impersonate legitimate websites or issue fake certificates, undermining trust in the entire TLS ecosystem. This highlights a dangerous imbalance: the focus has been on protecting data in transit, but not on securing the identity verification layer. The study underscores that true post-quantum resilience requires a holistic migration strategy covering both key exchange and public key infrastructure (PKI). Sectors driven by technology innovation show faster adoption, while legacy-dependent institutions lag. The persistence of outdated protocols and the absence of post-quantum certificate deployment leave the Internet exposed to Harvest-Now-Decrypt-Later (HNDL) attacks, where encrypted data is collected now for future decryption. The authors conclude that without coordinated, system-wide upgrades—including browser support, CA readiness, and server configuration—current security measures will remain fundamentally fragile in the face of quantum advances. Key Points: - 15.70% of domains, especially in banking and government, still use TLS 1.2, limiting post-quantum cryptographic agility. - 49.3% of domains support hybrid post-quantum key exchanges (e.g., MLKEM768 with X25519), while 50.7% rely solely on classical key exchange. - 0% of domains deploy hybrid post-quantum certificates, leaving the authentication layer vulnerable to quantum attacks. - Critical infrastructure sectors show slower adoption due to legacy system dependencies and complex migration paths. - The absence of post-quantum certificate support creates a critical gap, enabling potential certificate forgery by quantum adversaries. - Harvest-Now-Decrypt-Later (HNDL) attacks remain a serious long-term threat to current encrypted communications. - Technology-driven sectors are adopting post-quantum measures faster than traditional institutions. - Full quantum resilience requires coordinated upgrades across protocols, key exchange, and certificate authorities, not just isolated improvements. Notable Quotes: - "The results indicate that while modern protocols like TLS 1.3 and QUIC are gaining adoption, 15.70% of domains especially in critical sectors such as banking and government still rely on TLS 1.2." - "Notably, 0% adoption of hybrid post-quantum certificates was observed, leaving the authentication layer vulnerable to quantum-enabled attacks such as certificate forgery." - "Without such comprehensive migration, Internet communication systems remain vulnerable to long-term threats, including Harvest-Now-Decrypt-Later (HNDL) attacks." Data Points: - 32,011 domains analyzed in the study - 15.70% of domains still use TLS 1.2 - 49.3% of domains support hybrid post-quantum key exchange - 50.7% of domains use classical key exchange only - 0% of domains deploy hybrid post-quantum certificates - Study conducted in 2026 - Focus on MLKEM768 and X25519 in hybrid key exchange - Includes analysis of QUIC protocol adoption - Sectors studied include banking, government, technology, and education - TLS 1.3 adoption is increasing but not universal Controversial Claims: - The claim that 0% adoption of hybrid post-quantum certificates exists across all 32,011 domains may be contested if some private or experimental deployments were missed in the scan. - Asserting that critical sectors are 'lagging' may oversimplify institutional risk management strategies that prioritize stability over rapid cryptographic change. - The assumption that HNDL attacks are imminent or widely feasible by 2026 depends on unproven advances in quantum computing capability. Technical Terms: - TLS (Transport Layer Security): A cryptographic protocol securing communications over networks, commonly used for HTTPS. - Post-quantum cryptography (PQC): Cryptographic algorithms designed to resist attacks from quantum computers. - Hybrid key exchange: A security mechanism combining classical and post-quantum algorithms to protect against both current and future threats. - MLKEM768: A lattice-based key encapsulation mechanism selected by NIST as a post-quantum standard. - Certificate authority (CA): Trusted entities that issue digital certificates to verify website identities. - Harvest-Now-Decrypt-Later (HNDL): An attack strategy where encrypted data is collected today and decrypted later using future quantum computers. - Public Key Infrastructure (PKI): The framework supporting digital certificates and public-key encryption. - X25519: A widely used elliptic curve Diffie-Hellman key exchange algorithm. - Cipher suite: A set of algorithms used in TLS to secure a connection, including key exchange, encryption, and authentication methods. - QUIC: A modern transport protocol developed by Google, integrated with TLS 1.3 for faster, secure web connections. —Ada H. Pemberley Dispatch from The Prepared E0