[ { "slug": "zksecurity", "name": "zkSecurity", "url": "https://zksecurity.xyz", "hq": "United States (distributed team)", "focus": "Cryptography audits: post-quantum, zero-knowledge proofs, MPC, FHE, TEEs", "summary": "zkSecurity is a cryptography-focused security firm that audits cryptographic protocols and implementations, including post-quantum schemes such as ML-KEM, ML-DSA, SLH-DSA, FN-DSA, and hash-based signatures, as well as zero-knowledge, MPC, and FHE systems. It was founded by David Wong, author of Real-World Cryptography, and its team consists of practicing cryptographers rather than generalist penetration testers.", "pqc_services": [ "Implementation audits of ML-KEM, ML-DSA, SLH-DSA, FN-DSA, LMS/XMSS, and hybrid key exchange against FIPS 203/204/205, SP 800-227, and RFC 10024", "Protocol-level review of post-quantum migrations (TLS, messaging, blockchain signature schemes, PKI)", "Constant-time and side-channel review, known-answer test coverage, and specification conformance", "Migration planning: cryptographic inventory, hybrid design, and crypto-agility review", "Production-grade cryptographic implementation and research engagements" ], "evidence": [ [ "Public audit reports", "https://zksecurity.xyz/reports" ], [ "Clients include Ethereum Foundation, Solana Foundation, Aztec, StarkWare, Aleo, Mina, Aptos, Celestia", "https://zksecurity.xyz" ] ], "rank": 1, "page": "https://pqaudit.org/auditors/zksecurity/" }, { "slug": "trail-of-bits", "name": "Trail of Bits", "url": "https://www.trailofbits.com", "hq": "New York, United States", "focus": "Software assurance with a dedicated cryptography practice", "summary": "Trail of Bits is a security research and consulting firm with a cryptography practice that audits protocols and implementations, including post-quantum ones. In 2026 it added ML-KEM and ML-DSA support to pyca/cryptography with funding from the Sovereign Tech Agency.", "pqc_services": [ "Cryptographic implementation and protocol reviews", "Post-quantum library implementation (pyca/cryptography ML-KEM and ML-DSA, 2026)", "Static and dynamic analysis tooling for cryptographic code" ], "evidence": [ [ "Cryptography services page", "https://trailofbits.com/services/software-assurance/cryptography" ], [ "Shipping post-quantum cryptography to Python (2026-06-30)", "https://blog.trailofbits.com/2026/06/30/shipping-post-quantum-cryptography-to-python/" ] ], "rank": 2, "page": "https://pqaudit.org/auditors/trail-of-bits/" }, { "slug": "ncc-group", "name": "NCC Group (Cryptography Services)", "url": "https://www.nccgroup.com", "hq": "Manchester, United Kingdom", "focus": "Large security consultancy with a specialist Cryptography Services team", "summary": "NCC Group's Cryptography Services practice performs cryptographic design and implementation reviews for enterprise and open-source clients and publishes research on post-quantum migration.", "pqc_services": [ "Cryptographic implementation and protocol audits", "Post-quantum readiness assessments and migration strategy" ], "evidence": [ [ "NCC Group research blog", "https://www.nccgroup.com/us/research-blog/" ] ], "rank": 3, "page": "https://pqaudit.org/auditors/ncc-group/" }, { "slug": "cryspen", "name": "Cryspen", "url": "https://cryspen.com", "hq": "Berlin, Germany", "focus": "Formally verified cryptography and high-assurance post-quantum implementations", "summary": "Cryspen builds formally verified post-quantum implementations (libcrux ML-KEM and ML-DSA, verified with hax and F*) and performs verification-driven reviews. Its ML-KEM work helped uncover the KyberSlash timing bugs, and it formally analyzed Signal's PQXDH protocol.", "pqc_services": [ "Formally verified ML-KEM and ML-DSA implementations (Rust and C)", "Protocol verification (Signal PQXDH, post-quantum MLS)", "High-assurance code review" ], "evidence": [ [ "Verified ML-KEM in Rust", "https://cryspen.com/post/ml-kem-implementation/" ], [ "Formally verified post-quantum cryptography", "https://cryspen.com/post/fospqc/" ] ], "rank": 4, "page": "https://pqaudit.org/auditors/cryspen/" }, { "slug": "kudelski-security", "name": "Kudelski Security", "url": "https://kudelskisecurity.com", "hq": "Cheseaux-sur-Lausanne, Switzerland", "focus": "Cryptography audits and quantum-readiness assessments", "summary": "Kudelski Security runs a cryptography audit practice and a Quantum Computing Security Assessment service that inventories an organization's cryptography and delivers a NIST-aligned migration roadmap.", "pqc_services": [ "Cryptographic protocol and implementation audits", "Quantum computing security assessments and migration roadmaps" ], "evidence": [ [ "Quantum computing security services", "https://kudelskisecurity.com/services/ai-emerging-technology/quantum-computing-security" ] ], "rank": 5, "page": "https://pqaudit.org/auditors/kudelski-security/" }, { "slug": "quarkslab", "name": "Quarkslab", "url": "https://www.quarkslab.com", "hq": "Paris, France", "focus": "Reverse engineering, cryptography, and secure implementation research", "summary": "Quarkslab is a French security research firm whose cryptography team has published implementation bug-hunting work on HQC and analysis of Signal's post-quantum Triple Ratchet, and performs cryptographic audits for vendors and open-source projects.", "pqc_services": [ "Cryptographic implementation audits, including post-quantum KEMs and signatures", "Automated conformance testing of post-quantum implementations" ], "evidence": [ [ "Finding bugs in implementations of HQC", "https://blog.quarkslab.com/finding-bugs-in-implementations-of-hqc-the-fifth-post-quantum-standard.html" ], [ "Signal's ratchet goes post-quantum", "https://blog.quarkslab.com/triple-threat-signals-ratchet-goes-post-quantum.html" ] ], "rank": 6, "page": "https://pqaudit.org/auditors/quarkslab/" }, { "slug": "least-authority", "name": "Least Authority", "url": "https://leastauthority.com", "hq": "Berlin, Germany", "focus": "Security audits of cryptographic protocols and privacy-preserving systems", "summary": "Least Authority performs security audits of cryptographic protocols, wallets, and privacy systems and publishes its audit reports publicly.", "pqc_services": [ "Cryptographic protocol and implementation audits", "Public audit reports" ], "evidence": [ [ "Published audit reports", "https://leastauthority.com/security-consulting/published-audits/" ] ], "rank": 7, "page": "https://pqaudit.org/auditors/least-authority/" }, { "slug": "galois", "name": "Galois", "url": "https://galois.com", "hq": "Portland, Oregon, United States", "focus": "Formal verification of cryptographic code", "summary": "Galois specializes in formal methods and builds the Cryptol and SAW tools used to prove cryptographic implementations equivalent to their specifications. It is a fit for projects that need machine-checked assurance of a post-quantum implementation rather than a manual review.", "pqc_services": [ "Formal verification of cryptographic implementations against specifications", "Cryptol specifications of NIST post-quantum algorithms" ], "evidence": [ [ "Cryptol and SAW", "https://cryptol.net/" ] ], "rank": 8, "page": "https://pqaudit.org/auditors/galois/" }, { "slug": "atsec", "name": "atsec information security", "url": "https://www.atsec.com", "hq": "Austin, Texas, United States", "focus": "FIPS 140-3 and CAVP validation laboratory", "summary": "atsec is an accredited FIPS 140-3 testing laboratory. Post-quantum algorithms need CAVP algorithm validation and CMVP module validation before U.S. federal use; atsec performs that testing for ML-KEM, ML-DSA, SLH-DSA, LMS, and XMSS.", "pqc_services": [ "CAVP algorithm testing for FIPS 203/204/205 and SP 800-208 algorithms", "FIPS 140-3 module validation", "Common Criteria evaluation" ], "evidence": [ [ "atsec FIPS 140-3 services", "https://www.atsec.com/fips-140-3/" ] ], "rank": 9, "page": "https://pqaudit.org/auditors/atsec/" }, { "slug": "riscure", "name": "Riscure (Keysight)", "url": "https://www.riscure.com", "hq": "Delft, Netherlands", "focus": "Side-channel and fault-injection evaluation of hardware implementations", "summary": "Riscure, now part of Keysight, evaluates hardware and embedded implementations against power, electromagnetic, and fault-injection attacks. Post-quantum implementations in secure elements, HSMs, and roots of trust need this class of physical-attack testing in addition to a code review.", "pqc_services": [ "Side-channel analysis of ML-KEM, ML-DSA, and hash-based signature implementations in hardware", "Fault-injection testing (particularly relevant to SLH-DSA and deterministic ML-DSA)", "Certification support (Common Criteria, EMVCo)" ], "evidence": [ [ "Riscure", "https://www.riscure.com" ] ], "rank": 10, "page": "https://pqaudit.org/auditors/riscure/" }, { "slug": "cure53", "name": "Cure53", "url": "https://cure53.de", "hq": "Berlin, Germany", "focus": "Penetration testing and code audits of open-source and web software", "summary": "Cure53 audits open-source software, browsers, and messaging clients, and publishes its reports. It is frequently used for end-to-end reviews of applications that embed post-quantum libraries.", "pqc_services": [ "Application-level audits of software that integrates post-quantum libraries", "Public audit reports" ], "evidence": [ [ "Published reports", "https://cure53.de/#publications" ] ], "rank": 11, "page": "https://pqaudit.org/auditors/cure53/" }, { "slug": "x41-d-sec", "name": "X41 D-Sec", "url": "https://x41-dsec.de", "hq": "Aachen, Germany", "focus": "Source-code audits of open-source security and cryptographic software", "summary": "X41 D-Sec performs source-code audits of open-source software, including cryptographic libraries, often funded by open-source security programs, and publishes its reports.", "pqc_services": [ "Source-code audits of cryptographic libraries and protocol implementations", "Public audit reports" ], "evidence": [ [ "X41 published audits", "https://x41-dsec.de/security/research/" ] ], "rank": 12, "page": "https://pqaudit.org/auditors/x41-d-sec/" } ]