{
  "slug": "classic-mceliece",
  "name": "Classic McEliece",
  "aka": "McEliece (Goppa codes)",
  "kind": "Key-encapsulation mechanism (KEM)",
  "family": "Code-based (binary Goppa codes)",
  "standard": "ISO/IEC standardization in progress; not selected by NIST",
  "standard_url": "https://classic.mceliece.org/",
  "body": "ISO/IEC JTC 1/SC 27 (in progress); recommended by BSI (Germany) TR-02102-1",
  "date": "NIST fourth round concluded 2025-03-11 without selecting it",
  "status": "Not a NIST standard; ISO/IEC process ongoing",
  "summary": "Classic McEliece is the oldest post-quantum KEM design (1978) and the most conservative. NIST did not select it in the fourth round (2025-03-11) because of its very large public keys, but Germany's BSI recommends it in TR-02102-1 and it is being standardized through ISO/IEC. It matters for audits because European and defense customers deploy it.",
  "parameter_sets": [
    {
      "name": "mceliece348864",
      "category": 1,
      "pk": 261120,
      "sk": 6492,
      "ct_or_sig": 96
    },
    {
      "name": "mceliece460896",
      "category": 3,
      "pk": 524160,
      "sk": 13608,
      "ct_or_sig": 156
    },
    {
      "name": "mceliece6688128",
      "category": 5,
      "pk": 1044992,
      "sk": 13932,
      "ct_or_sig": 208
    }
  ],
  "size_label": "Ciphertext",
  "deployments": [
    "Mullvad VPN and some WireGuard-based products",
    "German and EU government contexts under BSI TR-02102-1"
  ],
  "audit_focus": [
    "Constant-time Goppa decoding (Berlekamp-Massey) and the Benes network for secret permutation",
    "Handling of the ~1 MB public key: memory safety, transport, caching",
    "Key generation failure handling and rejection sampling"
  ],
  "references": [
    [
      "Classic McEliece project",
      "https://classic.mceliece.org/"
    ],
    [
      "BSI TR-02102-1 Cryptographic Mechanisms",
      "https://www.bsi.bund.de/EN/Themen/Unternehmen-und-Organisationen/Standards-und-Zertifizierung/Technische-Richtlinien/TR-nach-Thema-sortiert/tr02102/tr02102_node.html"
    ]
  ],
  "url": "https://pqaudit.org/algorithms/classic-mceliece/",
  "updated": "2026-09-12"
}