Code-Based Cryptography

Cryptography built on the hardness of decoding random linear error-correcting codes, unbroken since 1978.

Core Principles & Analysis

• McEliece encryption from 1978 predates RSA deployment and still stands.
• Main cost is large public keys — Classic McEliece keys run to a megabyte.
• HQC was selected by NIST in 2025 as a code-based backup to ML-KEM.

Specifications & Metrics

• HARD PROBLEM: Syndrome decoding
• EXAMPLE: Classic McEliece, HQC, BIKE