Classic McEliece

Definition

Classic McEliece is a code-based key encapsulation mechanism selected by NIST as a post-quantum standard. Based on the McEliece cryptosystem from 1978, it offers exceptionally conservative security assumptions with decades of cryptanalysis, though with very large public keys.

Technical Explanation

Classic McEliece's security relies on the hardness of decoding random linear codes, a problem studied for over 60 years without efficient quantum or classical solutions. The scheme uses binary Goppa codes with carefully chosen parameters to resist all known attacks.

The primary drawback is key size: public keys range from 261 KB to 1.3 MB depending on security level. Ciphertexts are small (128-240 bytes), and operations are fast. The large keys make Classic McEliece unsuitable for bandwidth-constrained scenarios but ideal for long-term key establishment.

SynX Relevance

SynX architecture supports Classic McEliece for scenarios requiring maximum cryptographic conservatism. While Kyber-768 serves routine operations due to practical key sizes, Classic McEliece availability provides a fallback using entirely different mathematical foundations than lattice-based schemes.

Frequently Asked Questions

Why are Classic McEliece keys so large?: Code-based security requires representing large error-correcting code structures in public keys.
Is Classic McEliece more secure than Kyber?: It has longer cryptanalysis history; both are believed quantum-resistant with different mathematical foundations.
When would I use Classic McEliece?: For maximum long-term security where key size is acceptable, such as root key establishment.

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